{
 "instance": {
  "igms-20220630.htm": {
   "axisCustom": 0,
   "axisStandard": 20,
   "contextCount": 137,
   "dts": {
    "calculationLink": {
     "local": [
      "igms-20220630_cal.xml"
     ]
    },
    "definitionLink": {
     "local": [
      "igms-20220630_def.xml"
     ]
    },
    "inline": {
     "local": [
      "igms-20220630.htm"
     ]
    },
    "labelLink": {
     "local": [
      "igms-20220630_lab.xml"
     ]
    },
    "presentationLink": {
     "local": [
      "igms-20220630_pre.xml"
     ]
    },
    "schema": {
     "local": [
      "igms-20220630.xsd"
     ],
     "remote": [
      "http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xl-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xlink-2003-12-31.xsd",
      "http://www.xbrl.org/2005/xbrldt-2005.xsd",
      "http://www.xbrl.org/2006/ref-2006-02-27.xsd",
      "http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/reference-2009-12-16.xsd",
      "https://www.xbrl.org/2020/extensible-enumerations-2.0.xsd",
      "https://www.xbrl.org/dtr/type/2020-01-21/types.xsd",
      "https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd",
      "https://xbrl.fasb.org/srt/2021/elts/srt-roles-2021-01-31.xsd",
      "https://xbrl.fasb.org/srt/2021/elts/srt-types-2021-01-31.xsd",
      "https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd",
      "https://xbrl.fasb.org/us-gaap/2021/elts/us-roles-2021-01-31.xsd",
      "https://xbrl.fasb.org/us-gaap/2021/elts/us-types-2021-01-31.xsd",
      "https://xbrl.sec.gov/country/2021/country-2021.xsd",
      "https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd",
      "https://xbrl.sec.gov/stpr/2021/stpr-2021.xsd"
     ]
    }
   },
   "elementCount": 464,
   "entityCount": 1,
   "hidden": {
    "http://fasb.org/us-gaap/2021-01-31": 7,
    "http://xbrl.sec.gov/dei/2021q4": 4,
    "total": 11
   },
   "keyCustom": 44,
   "keyStandard": 171,
   "memberCustom": 16,
   "memberStandard": 21,
   "nsprefix": "igms",
   "nsuri": "http://igmbio.com/20220630",
   "report": {
    "R1": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentType",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "true",
     "longName": "100000 - Document - Document and Entity Information",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation",
     "shortName": "Document and Entity Information",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentType",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R10": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100120 - Disclosure - Fair Value Measurement",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurement",
     "shortName": "Fair Value Measurement",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R11": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SupplementalBalanceSheetDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100130 - Disclosure - Accrued Liabilities",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilities1",
     "shortName": "Accrued Liabilities",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SupplementalBalanceSheetDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R12": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CollaborativeArrangementDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100140 - Disclosure - License Agreements",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreements",
     "shortName": "License Agreements",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CollaborativeArrangementDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R13": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ClosedBlockDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100150 - Disclosure - Sanofi Agreement",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreement",
     "shortName": "Sanofi Agreement",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ClosedBlockDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R14": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100160 - Disclosure - Stockholders' Equity",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquity1",
     "shortName": "Stockholders' Equity",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R15": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100180 - Disclosure - Stock-Based Compensation",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensation",
     "shortName": "Stock-Based Compensation",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R16": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:EarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100190 - Disclosure - Net Loss Per Share Attributable to Common Stockholders",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholders",
     "shortName": "Net Loss Per Share Attributable to Common Stockholders",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:EarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R17": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SubsequentEventsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100220 - Disclosure - Subsequent Events",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEvents",
     "shortName": "Subsequent Events",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SubsequentEventsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R18": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "igms:DescriptionOfBusinessPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100230 - Disclosure - Summary of Significant Accounting Policies (Policies)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies",
     "shortName": "Summary of Significant Accounting Policies (Policies)",
     "subGroupType": "policies",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "igms:DescriptionOfBusinessPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R19": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:FairValueDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100240 - Disclosure - Fair Value Measurement (Tables)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementTables",
     "shortName": "Fair Value Measurement (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:FairValueDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R2": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:CashAndCashEquivalentsAtCarryingValue",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100010 - Statement - Condensed Consolidated Balance Sheets (Unaudited)",
     "role": "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
     "shortName": "Condensed Consolidated Balance Sheets (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_bc34f1c0-bda7-4bcf-ad8b-3022f446456e",
      "decimals": "-3",
      "lang": null,
      "name": "us-gaap:CashAndCashEquivalentsAtCarryingValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R20": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "us-gaap:SupplementalBalanceSheetDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAccruedLiabilitiesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100250 - Disclosure - Accrued Liabilities (Tables)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesTables",
     "shortName": "Accrued Liabilities (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "us-gaap:SupplementalBalanceSheetDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAccruedLiabilitiesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R21": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "igms:ScheduleOfConvertedCommonStockReservedForFutureIssuanceTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100260 - Disclosure - Stockholders' Equity (Tables)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityTables",
     "shortName": "Stockholders' Equity (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "igms:ScheduleOfConvertedCommonStockReservedForFutureIssuanceTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R22": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100270 - Disclosure - Stock-Based Compensation (Tables)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationTables",
     "shortName": "Stock-Based Compensation (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R23": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "us-gaap:EarningsPerShareTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100280 - Disclosure - Net Loss Per Share Attributable to Common Stockholders (Tables)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersTables",
     "shortName": "Net Loss Per Share Attributable to Common Stockholders (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "us-gaap:EarningsPerShareTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R24": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ProceedsFromIssuanceOfCommonStock",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100300 - Disclosure - Organization - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
     "shortName": "Organization - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R25": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:SegmentReportingPolicyPolicyTextBlock",
       "div",
       "us-gaap:SignificantAccountingPoliciesTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:NumberOfOperatingSegments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_Segment",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100310 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails",
     "shortName": "Summary of Significant Accounting Policies - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:SegmentReportingPolicyPolicyTextBlock",
       "div",
       "us-gaap:SignificantAccountingPoliciesTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:NumberOfOperatingSegments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_Segment",
      "xsiNil": "false"
     }
    },
    "R26": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:FairValueDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "0",
      "first": true,
      "lang": null,
      "name": "igms:NumberOfFinancialInstrumentsClassifiedAsLevelThree",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_Instrument",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100320 - Disclosure - Fair Value Measurement - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementAdditionalInformationDetails",
     "shortName": "Fair Value Measurement - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:FairValueDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "0",
      "first": true,
      "lang": null,
      "name": "igms:NumberOfFinancialInstrumentsClassifiedAsLevelThree",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_Instrument",
      "xsiNil": "false"
     }
    },
    "R27": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "us-gaap:FairValueDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "igms:CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAmortizedCostBasis",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100330 - Disclosure - Fair Value Measurement - Summary of Investments Measured and Recognized at Fair Value (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails",
     "shortName": "Fair Value Measurement - Summary of Investments Measured and Recognized at Fair Value (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "us-gaap:FairValueDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "igms:CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAmortizedCostBasis",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R28": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:InvestmentsClassifiedByContractualMaturityDateTableTextBlock",
       "div",
       "us-gaap:FairValueDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_ba94b01a-75f8-4a67-9bd6-fb7647100ba4",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "igms:AvailableForSaleSecuritiesDebtMaturitiesAndCashBeforeOneYearFairValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100340 - Disclosure - Fair Value Measurement - Summary of Contractual Maturities of Investments (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails",
     "shortName": "Fair Value Measurement - Summary of Contractual Maturities of Investments (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:InvestmentsClassifiedByContractualMaturityDateTableTextBlock",
       "div",
       "us-gaap:FairValueDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_ba94b01a-75f8-4a67-9bd6-fb7647100ba4",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "igms:AvailableForSaleSecuritiesDebtMaturitiesAndCashBeforeOneYearFairValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R29": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:PropertyPlantAndEquipmentNet",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100350 - Disclosure - Accrued Liabilities - Schedule of Property, Plant and Equipment, Net (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails",
     "shortName": "Accrued Liabilities - Schedule of Property, Plant and Equipment, Net (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R3": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:PreferredStockParOrStatedValuePerShare",
      "reportCount": 1,
      "unitRef": "U_UnitedStatesOfAmericaDollarsShare",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100040 - Statement - Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited)",
     "role": "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited",
     "shortName": "Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "INF",
      "lang": null,
      "name": "us-gaap:PreferredStockSharesIssued",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_shares",
      "xsiNil": "false"
     }
    },
    "R30": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:Depreciation",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100360 - Disclosure - Accrued Liabilities - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesAdditionalInformationDetails",
     "shortName": "Accrued Liabilities - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R31": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfAccruedLiabilitiesTableTextBlock",
       "div",
       "us-gaap:SupplementalBalanceSheetDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "igms:AccruedResearchAndDevelopmentMaterialsAndServicesCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100370 - Disclosure - Accrued Liabilities - Schedule of Accrued Liabilities (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails",
     "shortName": "Accrued Liabilities - Schedule of Accrued Liabilities (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfAccruedLiabilitiesTableTextBlock",
       "div",
       "us-gaap:SupplementalBalanceSheetDisclosuresTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "igms:AccruedResearchAndDevelopmentMaterialsAndServicesCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R32": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:CollaborativeArrangementDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_fd1b4cd0-65e6-4e33-abf3-ffaade39e5c7",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "igms:LicenseExpenses",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100380 - Disclosure - License Agreements - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails",
     "shortName": "License Agreements - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:CollaborativeArrangementDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_fd1b4cd0-65e6-4e33-abf3-ffaade39e5c7",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "igms:LicenseExpenses",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R33": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_f2836656-458e-45a6-8690-f577949754e0",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:StockIssuedDuringPeriodValueNewIssues",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100390 - Disclosure - Sanofi Agreement (Additional Information) (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails",
     "shortName": "Sanofi Agreement (Additional Information) (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:ClosedBlockDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_9805986e-43e3-46a0-916b-ce46013f7cca",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:Revenues",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R34": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:PreferredStockSharesAuthorized",
      "reportCount": 1,
      "unitRef": "U_shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100400 - Disclosure - Stockholders' Equity - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
     "shortName": "Stockholders' Equity - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "lang": "en-US",
      "name": "us-gaap:CommonStockVotingRights",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R35": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "igms:ScheduleOfConvertedCommonStockReservedForFutureIssuanceTableTextBlock",
       "div",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "igms:StockOptionsIssuedAndOutstanding",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100410 - Disclosure - Stockholders' Equity - Schedule of Number of Common Stock Reserved for Future Issuance (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails",
     "shortName": "Stockholders' Equity - Schedule of Number of Common Stock Reserved for Future Issuance (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "igms:ScheduleOfConvertedCommonStockReservedForFutureIssuanceTableTextBlock",
       "div",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "igms:StockOptionsIssuedAndOutstanding",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_shares",
      "xsiNil": "false"
     }
    },
    "R36": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ProceedsFromIssuanceOfCommonStock",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100420 - Disclosure - Stockholders' Equity - Pre-Funded Warrants - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
     "shortName": "Stockholders' Equity - Pre-Funded Warrants - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_875acd6e-f02c-4787-bcfa-dcbcc78c2dbd",
      "decimals": "4",
      "lang": null,
      "name": "igms:MaximumAllowedHoldingPercentageOfSharesAfterExerciseOfWarrants",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_pure",
      "xsiNil": "false"
     }
    },
    "R37": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_e8393481-af9c-44dd-b7d9-8e42c6eb96ba",
      "decimals": "2",
      "first": true,
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_pure",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100430 - Disclosure - Stock-Based Compensation - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails",
     "shortName": "Stock-Based Compensation - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_e8393481-af9c-44dd-b7d9-8e42c6eb96ba",
      "decimals": "2",
      "first": true,
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_pure",
      "xsiNil": "false"
     }
    },
    "R38": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
       "div",
       "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_1c6fdaca-e371-46f6-99e6-3420276ac048",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:AllocatedShareBasedCompensationExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100440 - Disclosure - Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails",
     "shortName": "Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
       "div",
       "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_1c6fdaca-e371-46f6-99e6-3420276ac048",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:AllocatedShareBasedCompensationExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R39": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock",
       "div",
       "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a1fbeb69-d162-4b61-a332-6ba3c46b0797",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100460 - Disclosure - Stock-Based Compensation - Summary of Company's stock awards granted (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails",
     "shortName": "Stock-Based Compensation - Summary of Company's stock awards granted (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock",
       "div",
       "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a1fbeb69-d162-4b61-a332-6ba3c46b0797",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_shares",
      "xsiNil": "false"
     }
    },
    "R4": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_f2836656-458e-45a6-8690-f577949754e0",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:RevenueFromCollaborativeArrangementExcludingRevenueFromContractWithCustomer",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100060 - Statement - Condensed Consolidated Statements of Operations (Unaudited)",
     "role": "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited",
     "shortName": "Condensed Consolidated Statements of Operations (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_f2836656-458e-45a6-8690-f577949754e0",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:RevenueFromCollaborativeArrangementExcludingRevenueFromContractWithCustomer",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R40": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
       "div",
       "us-gaap:EarningsPerShareTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "0",
      "first": true,
      "lang": null,
      "name": "us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100470 - Disclosure - Net Loss Per Share Attributable to Common Stockholders - Summary of Potentially Dilutive Securities Not Included in the Diluted Per Share Calculations (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails",
     "shortName": "Net Loss Per Share Attributable to Common Stockholders - Summary of Potentially Dilutive Securities Not Included in the Diluted Per Share Calculations (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
       "div",
       "us-gaap:EarningsPerShareTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "0",
      "first": true,
      "lang": null,
      "name": "us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_shares",
      "xsiNil": "false"
     }
    },
    "R41": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100480 - Disclosure - Commitments and Contingencies - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
     "shortName": "Commitments and Contingencies - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R42": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_97fd60d3-a29a-446d-b115-93f7be620393",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:OperatingLeaseLiabilityCurrent",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100490 - Disclosure - Commitments and Contingencies - Schedule of ROU Assets and Related Lease Liabilities (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfROUAssetsAndRelatedLeaseLiabilitiesDetails",
     "shortName": "Commitments and Contingencies - Schedule of ROU Assets and Related Lease Liabilities (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R43": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_62836b65-bb01-4920-a5fb-0cd7ea6723db",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:StockIssuedDuringPeriodSharesNewIssues",
      "reportCount": 1,
      "unitRef": "U_shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100510 - Disclosure - Related Party Transactions - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
     "shortName": "Related Party Transactions - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R44": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:SubsequentEventsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_3ead1dba-8212-478b-98a3-3b85823470b7",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "igms:LesseeOperatingLeaseExpiryMonthAndYears",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100520 - Disclosure - Subsequent Events - Additional Information (Details)",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails",
     "shortName": "Subsequent Events - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:SubsequentEventsTextBlock",
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_3ead1dba-8212-478b-98a3-3b85823470b7",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "igms:LesseeOperatingLeaseExpiryMonthAndYears",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R5": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_f2836656-458e-45a6-8690-f577949754e0",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:NetIncomeLoss",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100070 - Statement - Condensed Consolidated Statements of Comprehensive Loss (Unaudited)",
     "role": "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveLossUnaudited",
     "shortName": "Condensed Consolidated Statements of Comprehensive Loss (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_f2836656-458e-45a6-8690-f577949754e0",
      "decimals": "-3",
      "lang": null,
      "name": "us-gaap:ComprehensiveIncomeNetOfTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R6": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_448bdd23-2e47-4031-919d-ce5d6febc2eb",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:StockholdersEquity",
      "reportCount": 1,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100080 - Statement - Condensed Consolidated Statements of Stockholders' Equity (Unaudited)",
     "role": "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited",
     "shortName": "Condensed Consolidated Statements of Stockholders' Equity (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_7028385f-b5f1-4f79-9576-6ba56f12b433",
      "decimals": "-3",
      "lang": null,
      "name": "igms:StockIssuedDuringPeriodValueExerciseOfStockOptionsNetOfSharesWithheldForTaxesAndExerciseCosts",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R7": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ProfitLoss",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100090 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)",
     "role": "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited",
     "shortName": "Condensed Consolidated Statements of Cash Flows (Unaudited)",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "td",
       "tr",
       "table",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ProfitLoss",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_USD",
      "xsiNil": "false"
     }
    },
    "R8": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100100 - Disclosure - Organization",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganization",
     "shortName": "Organization",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R9": {
     "firstAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SignificantAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100110 - Disclosure - Summary of Significant Accounting Policies",
     "role": "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies",
     "shortName": "Summary of Significant Accounting Policies",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "div",
       "body",
       "html"
      ],
      "baseRef": "igms-20220630.htm",
      "contextRef": "C_a5b24fc8-2e0a-46bb-a257-aeec399ac9e8",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SignificantAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    }
   },
   "segmentCount": 40,
   "tag": {
    "dei_AmendmentFlag": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.",
        "label": "Amendment Flag",
        "terseLabel": "Amendment Flag"
       }
      }
     },
     "localname": "AmendmentFlag",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_CityAreaCode": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Area code of city",
        "label": "City Area Code",
        "terseLabel": "City Area Code"
       }
      }
     },
     "localname": "CityAreaCode",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_CoverAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cover page.",
        "label": "Cover [Abstract]"
       }
      }
     },
     "localname": "CoverAbstract",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "xbrltype": "stringItemType"
    },
    "dei_CurrentFiscalYearEndDate": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "End date of current fiscal year in the format --MM-DD.",
        "label": "Current Fiscal Year End Date",
        "terseLabel": "Current Fiscal Year End Date"
       }
      }
     },
     "localname": "CurrentFiscalYearEndDate",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "gMonthDayItemType"
    },
    "dei_DocumentFiscalPeriodFocus": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Fiscal period values are FY, Q1, Q2, and Q3.  1st, 2nd and 3rd quarter 10-Q or 10-QT statements have value Q1, Q2, and Q3 respectively, with 10-K, 10-KT or other fiscal year statements having FY.",
        "label": "Document Fiscal Period Focus",
        "terseLabel": "Document Fiscal Period Focus"
       }
      }
     },
     "localname": "DocumentFiscalPeriodFocus",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "fiscalPeriodItemType"
    },
    "dei_DocumentFiscalYearFocus": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "This is focus fiscal year of the document report in YYYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006.",
        "label": "Document Fiscal Year Focus",
        "terseLabel": "Document Fiscal Year Focus"
       }
      }
     },
     "localname": "DocumentFiscalYearFocus",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "gYearItemType"
    },
    "dei_DocumentPeriodEndDate": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period.  The format of the date is YYYY-MM-DD.",
        "label": "Document Period End Date",
        "terseLabel": "Document Period End Date"
       }
      }
     },
     "localname": "DocumentPeriodEndDate",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "dateItemType"
    },
    "dei_DocumentQuarterlyReport": {
     "auth_ref": [
      "r520"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Boolean flag that is true only for a form used as an quarterly report.",
        "label": "Document Quarterly Report",
        "terseLabel": "Document Quarterly Report"
       }
      }
     },
     "localname": "DocumentQuarterlyReport",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_DocumentTransitionReport": {
     "auth_ref": [
      "r521"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Boolean flag that is true only for a form used as a transition report.",
        "label": "Document Transition Report",
        "terseLabel": "Document Transition Report"
       }
      }
     },
     "localname": "DocumentTransitionReport",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_DocumentType": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.",
        "label": "Document Type",
        "terseLabel": "Document Type"
       }
      }
     },
     "localname": "DocumentType",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "submissionTypeItemType"
    },
    "dei_EntityAddressAddressLine1": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Address Line 1 such as Attn, Building Name, Street Name",
        "label": "Entity Address, Address Line One",
        "terseLabel": "Entity Address, Address Line One"
       }
      }
     },
     "localname": "EntityAddressAddressLine1",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressCityOrTown": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Name of the City or Town",
        "label": "Entity Address, City or Town",
        "terseLabel": "Entity Address, City or Town"
       }
      }
     },
     "localname": "EntityAddressCityOrTown",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressPostalZipCode": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Code for the postal or zip code",
        "label": "Entity Address, Postal Zip Code",
        "terseLabel": "Entity Address, Postal Zip Code"
       }
      }
     },
     "localname": "EntityAddressPostalZipCode",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressStateOrProvince": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Name of the state or province.",
        "label": "Entity Address, State or Province",
        "terseLabel": "Entity Address, State or Province"
       }
      }
     },
     "localname": "EntityAddressStateOrProvince",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "stateOrProvinceItemType"
    },
    "dei_EntityCentralIndexKey": {
     "auth_ref": [
      "r518"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.",
        "label": "Entity Central Index Key",
        "terseLabel": "Entity Central Index Key"
       }
      }
     },
     "localname": "EntityCentralIndexKey",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "centralIndexKeyItemType"
    },
    "dei_EntityCommonStockSharesOutstanding": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.",
        "label": "Entity Common Stock, Shares Outstanding",
        "terseLabel": "Entity Common Stock, Shares Outstanding"
       }
      }
     },
     "localname": "EntityCommonStockSharesOutstanding",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "sharesItemType"
    },
    "dei_EntityCurrentReportingStatus": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate 'Yes' or 'No' whether registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that registrants were required to file such reports), and (2) have been subject to such filing requirements for the past 90 days. This information should be based on the registrant's current or most recent filing containing the related disclosure.",
        "label": "Entity Current Reporting Status",
        "terseLabel": "Entity Current Reporting Status"
       }
      }
     },
     "localname": "EntityCurrentReportingStatus",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityEmergingGrowthCompany": {
     "auth_ref": [
      "r518"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate if registrant meets the emerging growth company criteria.",
        "label": "Entity Emerging Growth Company",
        "terseLabel": "Entity Emerging Growth Company"
       }
      }
     },
     "localname": "EntityEmergingGrowthCompany",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityExTransitionPeriod": {
     "auth_ref": [
      "r524"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate if an emerging growth company has elected not to use the extended transition period for complying with any new or revised financial accounting standards.",
        "label": "Entity Ex Transition Period",
        "terseLabel": "Entity Ex Transition Period"
       }
      }
     },
     "localname": "EntityExTransitionPeriod",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityFileNumber": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.",
        "label": "Entity File Number",
        "terseLabel": "Entity File Number"
       }
      }
     },
     "localname": "EntityFileNumber",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "fileNumberItemType"
    },
    "dei_EntityFilerCategory": {
     "auth_ref": [
      "r518"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate whether the registrant is one of the following: Large Accelerated Filer, Accelerated Filer, Non-accelerated Filer. Definitions of these categories are stated in Rule 12b-2 of the Exchange Act. This information should be based on the registrant's current or most recent filing containing the related disclosure.",
        "label": "Entity Filer Category",
        "terseLabel": "Entity Filer Category"
       }
      }
     },
     "localname": "EntityFilerCategory",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "filerCategoryItemType"
    },
    "dei_EntityIncorporationStateCountryCode": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Two-character EDGAR code representing the state or country of incorporation.",
        "label": "Entity Incorporation, State or Country Code",
        "terseLabel": "Entity Incorporation, State or Country Code"
       }
      }
     },
     "localname": "EntityIncorporationStateCountryCode",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "edgarStateCountryItemType"
    },
    "dei_EntityInteractiveDataCurrent": {
     "auth_ref": [
      "r523"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Boolean flag that is true when the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).",
        "label": "Entity Interactive Data Current",
        "terseLabel": "Entity Interactive Data Current"
       }
      }
     },
     "localname": "EntityInteractiveDataCurrent",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityRegistrantName": {
     "auth_ref": [
      "r518"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.",
        "label": "Entity Registrant Name",
        "terseLabel": "Entity Registrant Name"
       }
      }
     },
     "localname": "EntityRegistrantName",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityShellCompany": {
     "auth_ref": [
      "r518"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Boolean flag that is true when the registrant is a shell company as defined in Rule 12b-2 of the Exchange Act.",
        "label": "Entity Shell Company",
        "terseLabel": "Entity Shell Company"
       }
      }
     },
     "localname": "EntityShellCompany",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntitySmallBusiness": {
     "auth_ref": [
      "r518"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicates that the company is a Smaller Reporting Company (SRC).",
        "label": "Entity Small Business",
        "terseLabel": "Entity Small Business"
       }
      }
     },
     "localname": "EntitySmallBusiness",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityTaxIdentificationNumber": {
     "auth_ref": [
      "r518"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.",
        "label": "Entity Tax Identification Number",
        "terseLabel": "Entity Tax Identification Number"
       }
      }
     },
     "localname": "EntityTaxIdentificationNumber",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "employerIdItemType"
    },
    "dei_LocalPhoneNumber": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Local phone number for entity.",
        "label": "Local Phone Number",
        "terseLabel": "Local Phone Number"
       }
      }
     },
     "localname": "LocalPhoneNumber",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_Security12bTitle": {
     "auth_ref": [
      "r517"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Title of a 12(b) registered security.",
        "label": "Title of 12(b) Security",
        "terseLabel": "Title of 12(b) Security"
       }
      }
     },
     "localname": "Security12bTitle",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "securityTitleItemType"
    },
    "dei_SecurityExchangeName": {
     "auth_ref": [
      "r519"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Name of the Exchange on which a security is registered.",
        "label": "Security Exchange Name",
        "terseLabel": "Security Exchange Name"
       }
      }
     },
     "localname": "SecurityExchangeName",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "edgarExchangeCodeItemType"
    },
    "dei_TradingSymbol": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Trading symbol of an instrument as listed on an exchange.",
        "label": "Trading Symbol",
        "terseLabel": "Trading Symbol"
       }
      }
     },
     "localname": "TradingSymbol",
     "nsuri": "http://xbrl.sec.gov/dei/2021q4",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "tradingSymbolItemType"
    },
    "igms_AblexisIncMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Ablexis, Inc.",
        "label": "Ablexis Inc [Member]",
        "terseLabel": "Ablexis"
       }
      }
     },
     "localname": "AblexisIncMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_AccruedPropertyPlantAndEquipmentCurrent": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_AccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accrued property plant and equipment current.",
        "label": "Accrued Property Plant And Equipment Current",
        "terseLabel": "Accrued property, plant and equipment"
       }
      }
     },
     "localname": "AccruedPropertyPlantAndEquipmentCurrent",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_AccruedResearchAndDevelopmentExpensesPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accrued research and development expenses.",
        "label": "Accrued Research And Development Expenses Policy [Text Block]",
        "terseLabel": "Accrued Research and Development Expenses"
       }
      }
     },
     "localname": "AccruedResearchAndDevelopmentExpensesPolicyTextBlock",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "igms_AccruedResearchAndDevelopmentMaterialsAndServicesCurrent": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails": {
       "order": 0.0,
       "parentTag": "us-gaap_AccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accrued research and development materials and services current.",
        "label": "Accrued Research And Development Materials And Services Current",
        "terseLabel": "Accrued research and development materials and services"
       }
      }
     },
     "localname": "AccruedResearchAndDevelopmentMaterialsAndServicesCurrent",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_AccruedShareBasedCompensationExpense": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accrued share based compensation expense.",
        "label": "Accrued Share Based Compensation Expense",
        "terseLabel": "Accrued share based compensation expense"
       }
      }
     },
     "localname": "AccruedShareBasedCompensationExpense",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_AdditionalLeaseAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Additional lease agreements.",
        "label": "Additional Lease Agreement [Member]",
        "terseLabel": "Additional Lease Agreement"
       }
      }
     },
     "localname": "AdditionalLeaseAgreementMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_AdditionalMilestonePayment": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Additional milestone payment.",
        "label": "Additional Milestone Payment",
        "terseLabel": "Additional milestone payment"
       }
      }
     },
     "localname": "AdditionalMilestonePayment",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_AvailableForSaleSecuritiesDebtMaturitiesAndCashAfterOneYearFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails": {
       "order": 1.0,
       "parentTag": "igms_AvailableForSaleSecuritiesDebtSecuritiesAndCash",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Available for sale securities debt maturities and cash after one year fair value",
        "label": "Available For Sale Securities Debt Maturities And Cash After One Year Fair Value",
        "terseLabel": "Due in more than one year"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAndCashAfterOneYearFairValue",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_AvailableForSaleSecuritiesDebtMaturitiesAndCashBeforeOneYearFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails": {
       "order": 0.0,
       "parentTag": "igms_AvailableForSaleSecuritiesDebtSecuritiesAndCash",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Available for sale securities debt maturities and cash before one year fair value.",
        "label": "Available For Sale Securities Debt Maturities And Cash Before One Year Fair Value",
        "terseLabel": "Due in less than one year"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtMaturitiesAndCashBeforeOneYearFairValue",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_AvailableForSaleSecuritiesDebtSecuritiesAndCash": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Available for sale securities debt securities and cash.",
        "label": "Available For Sale Securities Debt Securities And Cash",
        "totalLabel": "Total"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtSecuritiesAndCash",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_CashAndCashEquivalentsAccumulatedGrossUnrealizedGainBeforeTax": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails3": {
       "order": 0.0,
       "parentTag": "igms_CashAndCashEquivalentsAmortizedCostBasis",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash and cash equivalents accumulated gross unrealized gain before tax.",
        "label": "Cash And Cash Equivalents Accumulated Gross Unrealized Gain Before Tax",
        "terseLabel": "Included within cash and cash equivalents, Gross Unrealized Gains"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAccumulatedGrossUnrealizedGainBeforeTax",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_CashAndCashEquivalentsAccumulatedGrossUnrealizedLossBeforeTax": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails3": {
       "order": 1.0,
       "parentTag": "igms_CashAndCashEquivalentsAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash and cash equivalents accumulated gross unrealized loss before tax.",
        "label": "Cash And Cash Equivalents Accumulated Gross Unrealized Loss Before Tax",
        "negatedLabel": "Included within cash and cash equivalents, Gross Unrealized Losses"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAccumulatedGrossUnrealizedLossBeforeTax",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_CashAndCashEquivalentsAmortizedCostBasis": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails3": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash and cash equivalents amortized cost basis.",
        "label": "Cash And Cash Equivalents Amortized Cost Basis",
        "totalLabel": "Included within cash and cash equivalents, Amortized Cost"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAmortizedCostBasis",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails": {
       "order": 0.0,
       "parentTag": "igms_CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash and cash equivalents and available for sale debt securities accumulated gross unrealized gain before tax.",
        "label": "Cash And Cash Equivalents And Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax",
        "terseLabel": "Gross Unrealized Gains"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails": {
       "order": 1.0,
       "parentTag": "igms_CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash and cash equivalents and available for sale debt securities accumulated gross unrealized loss before tax.",
        "label": "Cash And Cash Equivalents And Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax",
        "negatedLabel": "Gross Unrealized Losses"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAmortizedCostBasis": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash and cash equivalents and available for sale debt securities amortized cost basis.",
        "label": "Cash And Cash Equivalents And Available For Sale Debt Securities Amortized Cost Basis",
        "totalLabel": "Amortized Cost"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAmortizedCostBasis",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_CashAndCashEquivalentsAndAvailableForSaleSecuritiesDebtSecuritiesFairValue": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails": {
       "order": 2.0,
       "parentTag": "igms_CashAndCashEquivalentsAndAvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash and cash equivalents and available for sale securities debt securities fair value.",
        "label": "Cash And Cash Equivalents And Available For Sale Securities Debt Securities Fair Value",
        "terseLabel": "Fair Value"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAndAvailableForSaleSecuritiesDebtSecuritiesFairValue",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_CommonStockClassUndefinedMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Common stock class undefined member.",
        "label": "Common Stock Class Undefined [Member]",
        "terseLabel": "Common Stock Class Undefined"
       }
      }
     },
     "localname": "CommonStockClassUndefinedMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_CommonStockIncludingNonvotingCommonStockMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Common stock including nonvoting common stock.",
        "label": "Common Stock Including Nonvoting Common Stock [Member]",
        "terseLabel": "Common Stock Including Nonvoting Common Stock"
       }
      }
     },
     "localname": "CommonStockIncludingNonvotingCommonStockMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_ConsultantMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Consultant.",
        "label": "Consultant [Member]",
        "terseLabel": "Consultant"
       }
      }
     },
     "localname": "ConsultantMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_ContingentConsiderationsPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Contingent considerations.",
        "label": "Contingent Considerations Policy [Text Block]",
        "terseLabel": "Contingent Considerations"
       }
      }
     },
     "localname": "ContingentConsiderationsPolicyTextBlock",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "igms_DescriptionOfBusinessPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Description of business.",
        "label": "Description Of Business Policy [Text Block]",
        "terseLabel": "Description of the Business"
       }
      }
     },
     "localname": "DescriptionOfBusinessPolicyTextBlock",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "igms_DevelopmentAndRegulatoryMilestonesExchange": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Development and regulatory milestones exchange",
        "label": "Development and regulatory milestones exchange"
       }
      }
     },
     "localname": "DevelopmentAndRegulatoryMilestonesExchange",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_DocumentAndEntityInformationLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Document and entity information.",
        "label": "Document And Entity Information [Line Items]",
        "terseLabel": "Document and Entity Information [Line Items]"
       }
      }
     },
     "localname": "DocumentAndEntityInformationLineItems",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "stringItemType"
    },
    "igms_DocumentAndEntityInformationTable": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Document and entity information table.",
        "label": "Document And Entity Information [Table]",
        "terseLabel": "Document And Entity Information [Table]"
       }
      }
     },
     "localname": "DocumentAndEntityInformationTable",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "stringItemType"
    },
    "igms_EastMiddlefieldRoadMountainViewCaliforniaMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "East middlefield road mountain view california member.",
        "label": "East Middlefield Road Mountain View California [Member]",
        "terseLabel": "345 East Middlefield Road, Mountain View, California"
       }
      }
     },
     "localname": "EastMiddlefieldRoadMountainViewCaliforniaMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_EmployeeStockPurchasePlanNumberOfSharesAvailableForGrant": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_CommonStockCapitalSharesReservedForFutureIssuance",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Employee stock purchase plan number of shares available for grant.",
        "label": "Employee Stock Purchase Plan Number Of Shares Available For Grant",
        "terseLabel": "Employee stock purchase plan, available for future grants"
       }
      }
     },
     "localname": "EmployeeStockPurchasePlanNumberOfSharesAvailableForGrant",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_EstimatedSharesIssuableUnderEmployeeStockPurchasePlanMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Estimated shares issuable under employee stock purchase plan.",
        "label": "Estimated Shares Issuable Under Employee Stock Purchase Plan [Member]",
        "terseLabel": "Estimated Shares Issuable Under Employee Stock Purchase Plan"
       }
      }
     },
     "localname": "EstimatedSharesIssuableUnderEmployeeStockPurchasePlanMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_EuropeanMedicinesAgencyMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "European Medicines Agency",
        "label": "European Medicines Agency [Member]"
       }
      }
     },
     "localname": "EuropeanMedicinesAgencyMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_FinancialAssetsIncludedWithinCashAndCashEquivalentsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Financial assets included within cash and cash equivalents.",
        "label": "Financial Assets Included Within Cash And Cash Equivalents [Member]",
        "terseLabel": "Financial Assets Included Within Cash and Cash Equivalents"
       }
      }
     },
     "localname": "FinancialAssetsIncludedWithinCashAndCashEquivalentsMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_FinancialAssetsIncludedWithinLongTermInvestmentsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Financial assets included within long-term investments.",
        "label": "Financial Assets Included Within Long Term Investments [Member]",
        "terseLabel": "Financial Assets Included Within Long-Term Investments"
       }
      }
     },
     "localname": "FinancialAssetsIncludedWithinLongTermInvestmentsMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_FinancialAssetsIncludedWithinMarketableSecuritiesMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Financial Assets Included Within Marketable Securities",
        "label": "Financial Assets Included Within Marketable Securities [Member]"
       }
      }
     },
     "localname": "FinancialAssetsIncludedWithinMarketableSecuritiesMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_FinancialAssetsIncludedWithinShortTermInvestmentsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Financial assets included within short-term investments.",
        "label": "Financial Assets Included Within Short Term Investments [Member]",
        "terseLabel": "Financial Assets Included Within Short-Term Investments"
       }
      }
     },
     "localname": "FinancialAssetsIncludedWithinShortTermInvestmentsMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_FollowOnOfferingPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Follow-on offering.",
        "label": "Follow On Offering Policy [Text Block]",
        "terseLabel": "Follow-on Offering"
       }
      }
     },
     "localname": "FollowOnOfferingPolicyTextBlock",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "igms_IncreaseDecreaseInOperatingLeaseLiabilities": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 12.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Increase (decrease) in operating lease liabilities.",
        "label": "Increase Decrease In Operating Lease Liabilities",
        "terseLabel": "Lease liabilities, net"
       }
      }
     },
     "localname": "IncreaseDecreaseInOperatingLeaseLiabilities",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_IssuanceCostsForPublicOfferingsInAccountsPayable": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Issuance costs for public offerings in accounts payable.",
        "label": "Issuance Costs For Public Offerings in Accounts Payable",
        "terseLabel": "Issuance costs for public offerings in accounts payable"
       }
      }
     },
     "localname": "IssuanceCostsForPublicOfferingsInAccountsPayable",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_IssuanceOfFullyVestedRestrictedStockUnitsValue": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Issuance of fully vested restricted stock units, value",
        "label": "Issuance of fully vested restricted stock units, value",
        "terseLabel": "Issuance of fully vested restricted stock units, value"
       }
      }
     },
     "localname": "IssuanceOfFullyVestedRestrictedStockUnitsValue",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_LaboratoryEquipmentMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Laboratory equipment.",
        "label": "Laboratory Equipment [Member]",
        "terseLabel": "Manufacturing and laboratory equipment"
       }
      }
     },
     "localname": "LaboratoryEquipmentMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_LaboratoryLeaseMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "laboratory lease",
        "label": "laboratory lease [Member]",
        "terseLabel": "laboratory lease [Member]"
       }
      }
     },
     "localname": "LaboratoryLeaseMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_LeaseAgreementsOneMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Lease Agreements One [Member]",
        "terseLabel": "Lease Agreements One"
       }
      }
     },
     "localname": "LeaseAgreementsOneMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_LeaseAgreementsThreeMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Lease agreements three.",
        "label": "Lease Agreements Three [Member]",
        "terseLabel": "Lease Agreements Three"
       }
      }
     },
     "localname": "LeaseAgreementsThreeMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_LeaseAgreementsTwoMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Lease Agreements Two [Member]",
        "terseLabel": "Lease Agreements Two"
       }
      }
     },
     "localname": "LeaseAgreementsTwoMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_LesseeOperatingLeaseExpiryMonthAndYears": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Lessee operating lease expiry month and year.",
        "label": "Lessee Operating Lease Expiry Month And Years",
        "terseLabel": "Lessee operating lease expiry month and year"
       }
      }
     },
     "localname": "LesseeOperatingLeaseExpiryMonthAndYears",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "gYearMonthItemType"
    },
    "igms_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails": {
       "order": 5.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payment for operating lease due after fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).",
        "label": "Lessee, Operating Lease, Liability, to be Paid, after Year Four",
        "terseLabel": "Thereafter"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityToBePaidAfterYearFour",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_LicenseAgreementAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "License agreement.",
        "label": "License Agreement [Abstract]"
       }
      }
     },
     "localname": "LicenseAgreementAbstract",
     "nsuri": "http://igmbio.com/20220630",
     "xbrltype": "stringItemType"
    },
    "igms_LicenseAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "License agreement.",
        "label": "License Agreement [Member]",
        "terseLabel": "License Agreement"
       }
      }
     },
     "localname": "LicenseAgreementMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_LicenseAgreementPotentialMilestonePayments": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "License agreement, potential milestone payments.",
        "label": "License Agreement Potential Milestone Payments",
        "terseLabel": "Milestone payment based on achievement of specified development"
       }
      }
     },
     "localname": "LicenseAgreementPotentialMilestonePayments",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_LicenseAgreementUpfrontPaymentsPayable": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "License agreement upfront payments payable.",
        "label": "License Agreement Upfront Payments Payable",
        "terseLabel": "Upfront payment"
       }
      }
     },
     "localname": "LicenseAgreementUpfrontPaymentsPayable",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_LicenseExpenses": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "License expenses.",
        "label": "License Expenses",
        "terseLabel": "License expenses recognized"
       }
      }
     },
     "localname": "LicenseExpenses",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_LicenseFee": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "License fee.",
        "label": "License Fee",
        "terseLabel": "License fee"
       }
      }
     },
     "localname": "LicenseFee",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_LiquidityPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Liquidity.",
        "label": "Liquidity Policy [Text Block]",
        "terseLabel": "Liquidity"
       }
      }
     },
     "localname": "LiquidityPolicyTextBlock",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "igms_MaximumAllowedCombinedVotingPercentageOfSharesAfterExerciseOfWarrants": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Maximum allowed combined voting percentage of shares after exercise of warrants.",
        "label": "Maximum Allowed Combined Voting Percentage Of Shares After Exercise Of Warrants",
        "terseLabel": "Maximum allowed combined voting percentage of shares after exercise of warrants"
       }
      }
     },
     "localname": "MaximumAllowedCombinedVotingPercentageOfSharesAfterExerciseOfWarrants",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "igms_MaximumAllowedHoldingPercentageOfSharesAfterExerciseOfWarrants": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Maximum allowed holding percentage of shares after exercise of warrants.",
        "label": "Maximum Allowed Holding Percentage Of Shares After Exercise Of Warrants",
        "terseLabel": "Maximum allowed holding percentage of shares after exercise of warrants"
       }
      }
     },
     "localname": "MaximumAllowedHoldingPercentageOfSharesAfterExerciseOfWarrants",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "igms_MaximumAllowedPercentageOfPreFundedWarrantsToExercise": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Maximum allowed percentage of pre-funded warrants to exercise",
        "label": "Maximum Allowed Percentage Of Pre Funded Warrants To Exercise",
        "terseLabel": "Maximum allowed percentage of pre-funded warrants to exercise"
       }
      }
     },
     "localname": "MaximumAllowedPercentageOfPreFundedWarrantsToExercise",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "igms_MedivirABMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Medivir AB.",
        "label": "Medivir A B [Member]",
        "terseLabel": "Medivir AB"
       }
      }
     },
     "localname": "MedivirABMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_MinimumNoticeTermToIncreaseOrDecreaseHoldingPercentageOfPreFundedWarrants": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Minimum notice term to increase or decrease the holding percentage of pre-funded warrants.",
        "label": "Minimum Notice Term To Increase Or Decrease Holding Percentage Of Pre Funded Warrants",
        "terseLabel": "Minimum notice term to increase or decrease the holding percentage of pre-funded warrants"
       }
      }
     },
     "localname": "MinimumNoticeTermToIncreaseOrDecreaseHoldingPercentageOfPreFundedWarrants",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "igms_MountainViewCaliforniaMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Mountain View, California [Member]",
        "label": "Mountain View, California [Member]",
        "terseLabel": "Mountain View, California [Member]"
       }
      }
     },
     "localname": "MountainViewCaliforniaMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_NonCashLeaseExpense": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 5.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "label": "Non Cash Lease Expense",
        "terseLabel": "Non-cash lease expense"
       }
      }
     },
     "localname": "NonCashLeaseExpense",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_NorthWhismanRoadMountainViewCaliforniaMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "North whisman road mountain view california member.",
        "label": "North Whisman Road Mountain View California [Member]",
        "terseLabel": "440 Middlefield Road, Mountain View, California"
       }
      }
     },
     "localname": "NorthWhismanRoadMountainViewCaliforniaMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_NumberOfFinancialInstrumentsClassifiedAsLevelThree": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of financial instruments classified as level three.",
        "label": "Number Of Financial Instruments Classified As Level Three",
        "terseLabel": "Number of financial instruments classified as level 3"
       }
      }
     },
     "localname": "NumberOfFinancialInstrumentsClassifiedAsLevelThree",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementAdditionalInformationDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "igms_NumberOfLeaseAgreements": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of lease agreements",
        "label": "Number Of Lease Agreements",
        "terseLabel": "Number of lease agreements"
       }
      }
     },
     "localname": "NumberOfLeaseAgreements",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "igms_NumberOfRelatedPartyToWarrantIssued": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of related party to warrant issued.",
        "label": "Number Of Related Party To Warrant Issued",
        "terseLabel": "Number of related party to warrant issued"
       }
      }
     },
     "localname": "NumberOfRelatedPartyToWarrantIssued",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "igms_NumberOfVotingRightsForEachCommonStockHeld": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of voting rights for each common stock held.",
        "label": "Number Of Voting Rights For Each Common Stock Held",
        "terseLabel": "Number of common stock voting rights held"
       }
      }
     },
     "localname": "NumberOfVotingRightsForEachCommonStockHeld",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "igms_NumberOfWarrantsExercised": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of warrants exercised.",
        "label": "Number Of Warrants Exercised",
        "terseLabel": "Number of warrants exercised"
       }
      }
     },
     "localname": "NumberOfWarrantsExercised",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_OfficeLeaseMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Office lease",
        "label": "Office lease [Member]",
        "terseLabel": "Office lease [Member]"
       }
      }
     },
     "localname": "OfficeLeaseMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_OfficesAndLaboratoryMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Offices And Laboratory [Member]",
        "terseLabel": "Offices and Laboratory"
       }
      }
     },
     "localname": "OfficesAndLaboratoryMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_OperatingLeaseCommencementDate": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Operating lease commencement date.",
        "label": "Operating Lease Commencement Date",
        "terseLabel": "Operating lease commencement date"
       }
      }
     },
     "localname": "OperatingLeaseCommencementDate",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "dateItemType"
    },
    "igms_PercentageOfVotingPower": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Percentage Of Voting Power",
        "terseLabel": "Percentage of voting power"
       }
      }
     },
     "localname": "PercentageOfVotingPower",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "igms_PreFundedWarrantDisclosureTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Pre funded warrants disclosure.",
        "label": "Pre Funded Warrant Disclosure [Text Block]",
        "terseLabel": "Pre-Funded Warrants"
       }
      }
     },
     "localname": "PreFundedWarrantDisclosureTextBlock",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosurePreFundedWarrants"
     ],
     "xbrltype": "textBlockItemType"
    },
    "igms_PreFundedWarrants": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails": {
       "order": 4.0,
       "parentTag": "us-gaap_CommonStockCapitalSharesReservedForFutureIssuance",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Pre-funded warrants.",
        "label": "Pre Funded Warrants",
        "terseLabel": "Pre-funded warrants"
       }
      }
     },
     "localname": "PreFundedWarrants",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_PreFundedWarrantsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Pre funded warrants.",
        "label": "Pre Funded Warrants [Member]",
        "terseLabel": "Pre-funded Warrant"
       }
      }
     },
     "localname": "PreFundedWarrantsMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_ProceedsFromUnderwritingDiscountsAndCommissions": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Proceeds from underwriting discounts and commissions",
        "label": "Proceeds from underwriting discounts and commissions"
       }
      }
     },
     "localname": "ProceedsFromUnderwritingDiscountsAndCommissions",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_ProfitSharingRatioDescription": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Profit sharing ratio description",
        "label": "Profit sharing ratio description"
       }
      }
     },
     "localname": "ProfitSharingRatioDescription",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "igms_PublicOfferingMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Public offering.",
        "label": "Public Offering [Member]",
        "terseLabel": "Public Offering"
       }
      }
     },
     "localname": "PublicOfferingMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_PurchaseNetDiscountPremiumOnMarketableSecurities": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Purchase Net Discount (Premium) on Marketable Securities.",
        "label": "Purchase Net Discount (Premium) on Marketable Securities",
        "negatedLabel": "Purchase net discount (premium) on marketable securities"
       }
      }
     },
     "localname": "PurchaseNetDiscountPremiumOnMarketableSecurities",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_RestrictedStockUnits": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_CommonStockCapitalSharesReservedForFutureIssuance",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Restricted stock units.",
        "label": "Restricted Stock Units",
        "terseLabel": "Restricted stock units"
       }
      }
     },
     "localname": "RestrictedStockUnits",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_RevenueTransactionPrice": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Revenue Transaction Price",
        "label": "Revenue Transaction Price"
       }
      }
     },
     "localname": "RevenueTransactionPrice",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_SanofiAgreementAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sanofi Agreement",
        "label": "Sanofi Agreement [Abstract]"
       }
      }
     },
     "localname": "SanofiAgreementAbstract",
     "nsuri": "http://igmbio.com/20220630",
     "xbrltype": "stringItemType"
    },
    "igms_SanofiAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sanofi Agreement",
        "label": "Sanofi Agreement [Member]"
       }
      }
     },
     "localname": "SanofiAgreementMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_ScheduleOfConvertedCommonStockReservedForFutureIssuanceTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Schedule of converted common stock reserved for future issuance.",
        "label": "Schedule Of Converted Common Stock Reserved For Future Issuance Table [Text Block]",
        "terseLabel": "Schedule of Number of Common Stock Reserved for Future Issuance"
       }
      }
     },
     "localname": "ScheduleOfConvertedCommonStockReservedForFutureIssuanceTableTextBlock",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "igms_ScheduleOfOperatingLeaseRelatedToAssetsAndLiabilitiesTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Schedule of operating lease related to assets and liabilities.",
        "label": "Schedule Of Operating Lease Related To Assets And Liabilities Table [Text Block]",
        "terseLabel": "Schedule of ROU Assets and Related Lease Liabilities"
       }
      }
     },
     "localname": "ScheduleOfOperatingLeaseRelatedToAssetsAndLiabilitiesTableTextBlock",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "igms_ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceOfCommonStockPercent": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Exercise Price Of Common Stock Percent",
        "terseLabel": "Percentage of exercise price of stock option on estimated fair value of shares"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceOfCommonStockPercent",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "igms_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfShares": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Increase In Number Of Shares",
        "terseLabel": "Increase in number of shares"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfShares",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_StockIssuedDuringPeriodSharesExerciseByUnderwriters": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock Issued During Period Shares, Exercise by Underwriters.",
        "label": "Stock Issued During Period Shares Exercise By Underwriters",
        "terseLabel": "Common stock, exercised by underwriters"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesExerciseByUnderwriters",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_StockIssuedDuringPeriodSharesExerciseOfStockOptionsNetOfSharesWithheldForTaxesAndExerciseCosts": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock issued during period shares exercise of stock options net of shares withheld for taxes and exercise costs.",
        "label": "Stock Issued During Period Shares Exercise Of Stock Options Net Of Shares Withheld For Taxes And Exercise Costs",
        "terseLabel": "Exercise of stock options, net of shares withheld for taxes and exercise costs, shares"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesExerciseOfStockOptionsNetOfSharesWithheldForTaxesAndExerciseCosts",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_StockIssuedDuringPeriodSharesFullyVestedRestrictedStockUnits": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock issued during period shares fully vested restricted stock units.",
        "label": "Stock Issued During Period Shares Fully Vested Restricted Stock Units",
        "terseLabel": "Issuance of fully vested restricted stock units, shares"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesFullyVestedRestrictedStockUnits",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_StockIssuedDuringPeriodValueExerciseOfStockOptionsNetOfSharesWithheldForTaxesAndExerciseCosts": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock issued during period value exercise of stock options net of shares withheld for taxes and exercise costs.",
        "label": "Stock Issued During Period Value Exercise Of Stock Options Net Of Shares Withheld For Taxes And Exercise Costs",
        "terseLabel": "Exercise of stock options, net of shares withheld for taxes and exercise costs"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueExerciseOfStockOptionsNetOfSharesWithheldForTaxesAndExerciseCosts",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "igms_StockOptionsAndRestrictedStockUnitsFutureIssuance": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_CommonStockCapitalSharesReservedForFutureIssuance",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock options and restricted stock units, future issuance.",
        "label": "Stock Options And Restricted Stock Units Future Issuance",
        "terseLabel": "Stock options and restricted stock units, future issuance"
       }
      }
     },
     "localname": "StockOptionsAndRestrictedStockUnitsFutureIssuance",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_StockOptionsIssuedAndOutstanding": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails": {
       "order": 0.0,
       "parentTag": "us-gaap_CommonStockCapitalSharesReservedForFutureIssuance",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock options issued and outstanding.",
        "label": "Stock Options Issued And Outstanding",
        "terseLabel": "Stock options, issued and outstanding"
       }
      }
     },
     "localname": "StockOptionsIssuedAndOutstanding",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "igms_SummaryOfSignificantAccountingPoliciesLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Summary Of Significant Accounting Policies [Line Items]",
        "terseLabel": "Summary Of Significant Accounting Policies [Line Items]"
       }
      }
     },
     "localname": "SummaryOfSignificantAccountingPoliciesLineItems",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "igms_SummaryOfSignificantAccountingPoliciesTable": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Summary Of Significant Accounting Policies [Table]",
        "terseLabel": "Summary Of Significant Accounting Policies [Table]"
       }
      }
     },
     "localname": "SummaryOfSignificantAccountingPoliciesTable",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "igms_TenPercentStockholderMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Ten percent stockholder.",
        "label": "Ten Percent Stockholder [Member]",
        "terseLabel": "10% Stockholder"
       }
      }
     },
     "localname": "TenPercentStockholderMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_TwoThousandEighteenOmnibusIncentivePlanMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Two thousand eighteen omnibus incentive plan.",
        "label": "Two Thousand Eighteen Omnibus Incentive Plan [Member]",
        "terseLabel": "2018 Plan"
       }
      }
     },
     "localname": "TwoThousandEighteenOmnibusIncentivePlanMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_TwoThousandNineteenEmployeeStockPurchasePlanMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Two thousand nineteen employee stock purchase plan.",
        "label": "Two Thousand Nineteen Employee Stock Purchase Plan [Member]",
        "terseLabel": "ESPP"
       }
      }
     },
     "localname": "TwoThousandNineteenEmployeeStockPurchasePlanMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_TwoThousandTenStockPlanTwoThousandEighteenStockPlanAndEmployeeStockPurchasePlanMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "2010 plan 2018 plan and employee stock purchase plan.",
        "label": "Two Thousand Ten Stock Plan Two Thousand Eighteen Stock Plan And Employee Stock Purchase Plan [Member]",
        "terseLabel": "2010 Plan, 2018 Plan and ESPP"
       }
      }
     },
     "localname": "TwoThousandTenStockPlanTwoThousandEighteenStockPlanAndEmployeeStockPurchasePlanMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_UnderwrittenPublicOfferingMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Underwritten public offering.",
        "label": "Underwritten Public Offering [Member]",
        "terseLabel": "Underwritten Public Offering"
       }
      }
     },
     "localname": "UnderwrittenPublicOfferingMember",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "igms_UnpaidAmountsRelatedToPurchaseOfPropertyPlantAndEquipment": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Unpaid amounts related to purchase of property, plant and equipment",
        "label": "Unpaid amounts related to purchase of property, plant and equipment"
       }
      }
     },
     "localname": "UnpaidAmountsRelatedToPurchaseOfPropertyPlantAndEquipment",
     "nsuri": "http://igmbio.com/20220630",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "srt_CounterpartyNameAxis": {
     "auth_ref": [
      "r47",
      "r49",
      "r96",
      "r97",
      "r225",
      "r237"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Counterparty Name [Axis]",
        "terseLabel": "Counterparty Name"
       }
      }
     },
     "localname": "CounterpartyNameAxis",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_DirectorMember": {
     "auth_ref": [
      "r163"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Director [Member]",
        "terseLabel": "Board of Directors"
       }
      }
     },
     "localname": "DirectorMember",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_ExecutiveOfficerMember": {
     "auth_ref": [
      "r163"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Executive Officer [Member]",
        "terseLabel": "Executive Officer"
       }
      }
     },
     "localname": "ExecutiveOfficerMember",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MaximumMember": {
     "auth_ref": [
      "r224",
      "r236",
      "r273",
      "r274",
      "r414",
      "r415",
      "r416",
      "r417",
      "r418",
      "r419",
      "r420",
      "r467",
      "r470",
      "r514",
      "r515"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Maximum [Member]",
        "terseLabel": "Maximum"
       }
      }
     },
     "localname": "MaximumMember",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MinimumMember": {
     "auth_ref": [
      "r224",
      "r236",
      "r273",
      "r274",
      "r414",
      "r415",
      "r416",
      "r417",
      "r418",
      "r419",
      "r420",
      "r467",
      "r470",
      "r514",
      "r515"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Minimum [Member]",
        "terseLabel": "Minimum"
       }
      }
     },
     "localname": "MinimumMember",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_ProductOrServiceAxis": {
     "auth_ref": [
      "r159",
      "r260",
      "r261",
      "r422",
      "r466",
      "r468"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Product and Service [Axis]"
       }
      }
     },
     "localname": "ProductOrServiceAxis",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_ProductsAndServicesDomain": {
     "auth_ref": [
      "r159",
      "r260",
      "r261",
      "r422",
      "r466",
      "r468"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Product and Service [Domain]"
       }
      }
     },
     "localname": "ProductsAndServicesDomain",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RangeAxis": {
     "auth_ref": [
      "r224",
      "r236",
      "r263",
      "r273",
      "r274",
      "r414",
      "r415",
      "r416",
      "r417",
      "r418",
      "r419",
      "r420",
      "r467",
      "r470",
      "r514",
      "r515"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statistical Measurement [Axis]",
        "terseLabel": "Statistical Measurement"
       }
      }
     },
     "localname": "RangeAxis",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_RangeMember": {
     "auth_ref": [
      "r224",
      "r236",
      "r263",
      "r273",
      "r274",
      "r414",
      "r415",
      "r416",
      "r417",
      "r418",
      "r419",
      "r420",
      "r467",
      "r470",
      "r514",
      "r515"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statistical Measurement [Domain]",
        "terseLabel": "Statistical Measurement"
       }
      }
     },
     "localname": "RangeMember",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RepurchaseAgreementCounterpartyNameDomain": {
     "auth_ref": [
      "r48",
      "r49",
      "r96",
      "r97",
      "r225",
      "r237"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Counterparty Name [Domain]",
        "terseLabel": "Counterparty Name"
       }
      }
     },
     "localname": "RepurchaseAgreementCounterpartyNameDomain",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_SegmentGeographicalDomain": {
     "auth_ref": [
      "r160",
      "r161",
      "r260",
      "r262",
      "r469",
      "r505",
      "r506",
      "r507",
      "r508",
      "r509",
      "r510",
      "r511",
      "r512",
      "r513"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Geographical [Domain]",
        "terseLabel": "Geographical"
       }
      }
     },
     "localname": "SegmentGeographicalDomain",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_StatementGeographicalAxis": {
     "auth_ref": [
      "r160",
      "r161",
      "r260",
      "r262",
      "r469",
      "r501",
      "r505",
      "r506",
      "r507",
      "r508",
      "r509",
      "r510",
      "r511",
      "r512",
      "r513"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Geographical [Axis]",
        "terseLabel": "Geographical"
       }
      }
     },
     "localname": "StatementGeographicalAxis",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_TitleOfIndividualAxis": {
     "auth_ref": [
      "r163",
      "r401"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Title of Individual [Axis]",
        "terseLabel": "Title of Individual"
       }
      }
     },
     "localname": "TitleOfIndividualAxis",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_TitleOfIndividualWithRelationshipToEntityDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Title of Individual [Domain]",
        "terseLabel": "Title of Individual"
       }
      }
     },
     "localname": "TitleOfIndividualWithRelationshipToEntityDomain",
     "nsuri": "http://fasb.org/srt/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "stpr_CA": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "CALIFORNIA",
        "terseLabel": "Mountain View, California"
       }
      }
     },
     "localname": "CA",
     "nsuri": "http://xbrl.sec.gov/stpr/2021",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccountingPoliciesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Accounting Policies [Abstract]"
       }
      }
     },
     "localname": "AccountingPoliciesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccountingStandardsUpdate201912Member": {
     "auth_ref": [
      "r315",
      "r316",
      "r317",
      "r318"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accounting Standards Update 2019-12 Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.",
        "label": "Accounting Standards Update 2019-12 [Member]",
        "terseLabel": "ASU 2019-12"
       }
      }
     },
     "localname": "AccountingStandardsUpdate201912Member",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent": {
     "auth_ref": [
      "r444",
      "r461"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sum of the carrying values as of the balance sheet date of obligations incurred through that date, including liabilities incurred and payable to vendors for goods and services received, taxes, interest, rent and utilities, compensation costs, payroll taxes and fringe benefits (other than pension and postretirement obligations), contractual rights and obligations, and statutory obligations.",
        "label": "Accounts Payable and Accrued Liabilities",
        "terseLabel": "Upfront payment received",
        "totalLabel": "Accounts Payable and Accrued Liabilities, Total"
       }
      }
     },
     "localname": "AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccountsPayableCurrent": {
     "auth_ref": [
      "r36",
      "r407"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_LiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).",
        "label": "Accounts Payable, Current",
        "terseLabel": "Accounts payable",
        "totalLabel": "Accounts Payable, Current, Total"
       }
      }
     },
     "localname": "AccountsPayableCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments": {
     "auth_ref": [
      "r82"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method.",
        "label": "Accretion (Amortization) of Discounts and Premiums, Investments",
        "negatedLabel": "Net amortization of premiums on marketable securities"
       }
      }
     },
     "localname": "AccretionAmortizationOfDiscountsAndPremiumsInvestments",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccruedEmployeeBenefitsCurrent": {
     "auth_ref": [
      "r12",
      "r13",
      "r39"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_AccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Carrying value as of the balance sheet date of obligations, excluding pension and other postretirement benefits, incurred through that date and payable for perquisites provided to employees pertaining to services received from them. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).",
        "label": "Accrued Employee Benefits, Current",
        "terseLabel": "Accrued compensation"
       }
      }
     },
     "localname": "AccruedEmployeeBenefitsCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccruedLiabilitiesCurrent": {
     "auth_ref": [
      "r39"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_LiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).",
        "label": "Accrued Liabilities, Current",
        "terseLabel": "Accrued liabilities",
        "totalLabel": "Total accrued liabilities"
       }
      }
     },
     "localname": "AccruedLiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccruedProfessionalFeesCurrent": {
     "auth_ref": [
      "r12",
      "r13",
      "r39"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_AccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).",
        "label": "Accrued Professional Fees, Current",
        "terseLabel": "Accrued professional services"
       }
      }
     },
     "localname": "AccruedProfessionalFeesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment": {
     "auth_ref": [
      "r33",
      "r200"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_PropertyPlantAndEquipmentNet",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.",
        "label": "Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment",
        "negatedLabel": "Less: Accumulated depreciation",
        "periodEndLabel": "Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance",
        "periodStartLabel": "Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance",
        "totalLabel": "Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total"
       }
      }
     },
     "localname": "AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax": {
     "auth_ref": [
      "r23",
      "r53",
      "r54",
      "r55",
      "r455",
      "r478",
      "r482"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_StockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.",
        "label": "Accumulated Other Comprehensive Income (Loss), Net of Tax",
        "terseLabel": "Accumulated other comprehensive loss",
        "totalLabel": "Accumulated Other Comprehensive Income (Loss), Net of Tax, Total"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeLossNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeMember": {
     "auth_ref": [
      "r52",
      "r55",
      "r61",
      "r62",
      "r63",
      "r99",
      "r100",
      "r101",
      "r333",
      "r473",
      "r474",
      "r529"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accumulated increase (decrease) in equity from transactions and other events and circumstances from non-owner sources, attributable to the parent. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners.",
        "label": "AOCI Attributable to Parent [Member]",
        "terseLabel": "Accumulated Other Comprehensive Income (Loss)"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdditionalPaidInCapitalCommonStock": {
     "auth_ref": [
      "r21"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_StockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Value received from shareholders in common stock-related transactions that are in excess of par value or stated value and amounts received from other stock-related transactions. Includes only common stock transactions (excludes preferred stock transactions). May be called contributed capital, capital in excess of par, capital surplus, or paid-in capital.",
        "label": "Additional Paid in Capital, Common Stock",
        "periodEndLabel": "Additional Paid in Capital, Common Stock, Ending Balance",
        "periodStartLabel": "Additional Paid in Capital, Common Stock, Beginning Balance",
        "terseLabel": "Additional paid-in-capital"
       }
      }
     },
     "localname": "AdditionalPaidInCapitalCommonStock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AdditionalPaidInCapitalMember": {
     "auth_ref": [
      "r99",
      "r100",
      "r101",
      "r305",
      "r306",
      "r307",
      "r351"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders.",
        "label": "Additional Paid-in Capital [Member]",
        "terseLabel": "Additional Paid-in Capital"
       }
      }
     },
     "localname": "AdditionalPaidInCapitalMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdjustmentsForNewAccountingPronouncementsAxis": {
     "auth_ref": [
      "r0",
      "r1",
      "r2",
      "r3",
      "r4",
      "r103",
      "r104",
      "r105",
      "r106",
      "r115",
      "r165",
      "r166",
      "r181",
      "r182",
      "r183",
      "r184",
      "r186",
      "r187",
      "r212",
      "r301",
      "r302",
      "r303",
      "r304",
      "r305",
      "r306",
      "r307",
      "r308",
      "r315",
      "r316",
      "r317",
      "r318",
      "r343",
      "r344",
      "r345",
      "r346",
      "r347",
      "r348",
      "r349",
      "r350",
      "r351",
      "r352",
      "r353",
      "r364",
      "r365",
      "r367",
      "r368",
      "r369",
      "r370",
      "r371",
      "r372",
      "r395",
      "r424",
      "r425",
      "r426",
      "r471",
      "r472",
      "r473",
      "r474",
      "r475",
      "r476",
      "r477",
      "r478",
      "r479",
      "r480",
      "r481",
      "r482",
      "r525",
      "r526",
      "r527",
      "r528",
      "r529"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by amendment to accounting standards.",
        "label": "Accounting Standards Update [Axis]",
        "terseLabel": "Accounting Standards Update"
       }
      }
     },
     "localname": "AdjustmentsForNewAccountingPronouncementsAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue": {
     "auth_ref": [
      "r275",
      "r277",
      "r310",
      "r311"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of increase to additional paid-in capital (APIC) for recognition of cost for award under share-based payment arrangement.",
        "label": "APIC, Share-based Payment Arrangement, Increase for Cost Recognition",
        "terseLabel": "Stock-based compensation expense",
        "totalLabel": "APIC, Share-based Payment Arrangement, Increase for Cost Recognition, Total"
       }
      }
     },
     "localname": "AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]",
        "terseLabel": "Adjustments to reconcile net loss to net cash used in operating activities:"
       }
      }
     },
     "localname": "AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AllocatedShareBasedCompensationExpense": {
     "auth_ref": [
      "r277",
      "r297",
      "r309"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.",
        "label": "Share-based Payment Arrangement, Expense",
        "terseLabel": "Total stock-based compensation expense",
        "verboseLabel": "Total stock-based compensation expense"
       }
      }
     },
     "localname": "AllocatedShareBasedCompensationExpense",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount": {
     "auth_ref": [
      "r123"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.",
        "label": "Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount",
        "terseLabel": "Potentially dilutive securities not included in diluted per share calculations"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis": {
     "auth_ref": [
      "r123"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of antidilutive security.",
        "label": "Antidilutive Securities [Axis]",
        "terseLabel": "Antidilutive Securities"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]",
        "terseLabel": "Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AntidilutiveSecuritiesNameDomain": {
     "auth_ref": [
      "r123"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Incremental common shares attributable to securities that were not included in diluted earnings per share (EPS) because to do so would increase EPS amounts or decrease loss per share amounts for the period presented.",
        "label": "Antidilutive Securities, Name [Domain]",
        "terseLabel": "Antidilutive Securities, Name"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ArrangementsAndNonarrangementTransactionsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Collaborative arrangement and arrangement other than collaborative applicable to revenue-generating activity or operations.",
        "label": "Collaborative Arrangement and Arrangement Other than Collaborative [Domain]",
        "terseLabel": "Collaborative Arrangement and Arrangement Other than Collaborative"
       }
      }
     },
     "localname": "ArrangementsAndNonarrangementTransactionsMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_Assets": {
     "auth_ref": [
      "r94",
      "r142",
      "r151",
      "r157",
      "r177",
      "r213",
      "r214",
      "r215",
      "r216",
      "r217",
      "r218",
      "r219",
      "r220",
      "r221",
      "r222",
      "r223",
      "r329",
      "r334",
      "r363",
      "r405",
      "r407",
      "r441",
      "r453"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.",
        "label": "Assets",
        "totalLabel": "Total assets"
       }
      }
     },
     "localname": "Assets",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Assets [Abstract]",
        "terseLabel": "Assets"
       }
      }
     },
     "localname": "AssetsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AssetsAndLiabilitiesLesseeAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Assets and Liabilities, Lessee [Abstract]"
       }
      }
     },
     "localname": "AssetsAndLiabilitiesLesseeAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_AssetsCurrent": {
     "auth_ref": [
      "r10",
      "r11",
      "r46",
      "r94",
      "r177",
      "r213",
      "r214",
      "r215",
      "r216",
      "r217",
      "r218",
      "r219",
      "r220",
      "r221",
      "r222",
      "r223",
      "r329",
      "r334",
      "r363",
      "r405",
      "r407"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold, or consumed within one year (or the normal operating cycle, if longer). Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.",
        "label": "Assets, Current",
        "totalLabel": "Total current assets"
       }
      }
     },
     "localname": "AssetsCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsCurrentAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Assets, Current [Abstract]",
        "terseLabel": "Current assets:"
       }
      }
     },
     "localname": "AssetsCurrentAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax": {
     "auth_ref": [
      "r173"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails2": {
       "order": 0.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax",
        "terseLabel": "Included within short-term/long-term investments, Gross Unrealized Gains"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax": {
     "auth_ref": [
      "r174"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails2": {
       "order": 1.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax",
        "negatedLabel": "Included within short-term/long-term investments, Gross Unrealized Losses"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis": {
     "auth_ref": [
      "r171",
      "r188"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails2": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Debt Securities, Available-for-sale, Amortized Cost",
        "totalLabel": "Included within short-term/long-term investments, Amortized Cost"
       }
      }
     },
     "localname": "AvailableForSaleDebtSecuritiesAmortizedCostBasis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtSecurities": {
     "auth_ref": [
      "r168",
      "r172",
      "r188",
      "r443"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails2": {
       "order": 2.0,
       "parentTag": "us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Debt Securities, Available-for-sale",
        "terseLabel": "Included within short-term/long-term investments, Fair Value",
        "totalLabel": "Debt Securities, Available-for-sale, Total"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtSecurities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent": {
     "auth_ref": [
      "r170",
      "r188"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as noncurrent.",
        "label": "Debt Securities, Available-for-sale, Noncurrent",
        "terseLabel": "Long-term investments"
       }
      }
     },
     "localname": "AvailableForSaleSecuritiesDebtSecuritiesNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AwardTypeAxis": {
     "auth_ref": [
      "r278",
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of award under share-based payment arrangement.",
        "label": "Award Type [Axis]",
        "terseLabel": "Award Type"
       }
      }
     },
     "localname": "AwardTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_BalanceSheetRelatedDisclosuresAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Balance Sheet Related Disclosures [Abstract]"
       }
      }
     },
     "localname": "BalanceSheetRelatedDisclosuresAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_BasisOfAccountingPolicyPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for basis of accounting, or basis of presentation, used to prepare the financial statements (for example, US Generally Accepted Accounting Principles, Other Comprehensive Basis of Accounting, IFRS).",
        "label": "Basis of Accounting, Policy [Policy Text Block]",
        "terseLabel": "Basis of Presentation"
       }
      }
     },
     "localname": "BasisOfAccountingPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CapitalExpendituresIncurredButNotYetPaid": {
     "auth_ref": [
      "r85",
      "r86",
      "r87"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Future cash outflow to pay for purchases of fixed assets that have occurred.",
        "label": "Capital Expenditures Incurred but Not yet Paid",
        "terseLabel": "Unpaid amounts related to purchase of property, plant and equipment"
       }
      }
     },
     "localname": "CapitalExpendituresIncurredButNotYetPaid",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsAtCarryingValue": {
     "auth_ref": [
      "r8",
      "r30",
      "r83"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_AssetsCurrent",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.",
        "label": "Cash and Cash Equivalents, at Carrying Value",
        "periodEndLabel": "Cash and Cash Equivalents, at Carrying Value, Ending Balance",
        "periodStartLabel": "Cash and Cash Equivalents, at Carrying Value, Beginning Balance",
        "terseLabel": "Cash and cash equivalents",
        "totalLabel": "Cash and Cash Equivalents, at Carrying Value, Total"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAtCarryingValue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsFairValueDisclosure": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails3": {
       "order": 2.0,
       "parentTag": "igms_CashAndCashEquivalentsAmortizedCostBasis",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Cash and Cash Equivalents, Fair Value Disclosure",
        "terseLabel": "Included within cash and cash equivalents, Fair Value"
       }
      }
     },
     "localname": "CashAndCashEquivalentsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy": {
     "auth_ref": [
      "r15",
      "r84",
      "r440"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Entity's cash and cash equivalents accounting policy with respect to restricted balances.  Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits.",
        "label": "Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]",
        "terseLabel": "Cash, Cash Equivalents and Restricted Cash"
       }
      }
     },
     "localname": "CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents": {
     "auth_ref": [
      "r78",
      "r83",
      "r88"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents",
        "periodEndLabel": "Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance",
        "periodStartLabel": "Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning Balance",
        "totalLabel": "Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Total"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations": {
     "auth_ref": [
      "r78",
      "r83",
      "r88"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including, but not limited to, disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations",
        "periodEndLabel": "End of period",
        "periodStartLabel": "Beginning of period",
        "totalLabel": "Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations, Total"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect": {
     "auth_ref": [
      "r78",
      "r373"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of increase (decrease) in cash, cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including effect from exchange rate change. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect",
        "totalLabel": "Net increase in cash, cash equivalents, and restricted cash"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]",
        "terseLabel": "Supplemental disclosure of non-cash investing and financing activities:"
       }
      }
     },
     "localname": "CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdopted": {
     "auth_ref": [
      "r0",
      "r1",
      "r99",
      "r100",
      "r102",
      "r165",
      "r166",
      "r178",
      "r179",
      "r180",
      "r181",
      "r182",
      "r212",
      "r301",
      "r302",
      "r303",
      "r315",
      "r339",
      "r343",
      "r344",
      "r364",
      "r366",
      "r367",
      "r368",
      "r371",
      "r372",
      "r381",
      "r395",
      "r424",
      "r425",
      "r471",
      "r472",
      "r525"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicates (true false) whether accounting standards update was adopted.",
        "label": "Change in Accounting Principle, Accounting Standards Update, Adopted [true false]",
        "terseLabel": "Change in accounting principle, accounting standards update, adopted"
       }
      }
     },
     "localname": "ChangeInAccountingPrincipleAccountingStandardsUpdateAdopted",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "booleanItemType"
    },
    "us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdoptionDate": {
     "auth_ref": [
      "r0",
      "r1",
      "r99",
      "r100",
      "r109",
      "r165",
      "r166",
      "r178",
      "r179",
      "r180",
      "r181",
      "r182",
      "r212",
      "r301",
      "r302",
      "r303",
      "r315",
      "r339",
      "r343",
      "r344",
      "r345",
      "r348",
      "r364",
      "r366",
      "r367",
      "r368",
      "r371",
      "r372",
      "r381",
      "r395",
      "r424",
      "r425",
      "r471",
      "r472",
      "r525"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Date accounting standards update was adopted, in YYYY-MM-DD format.",
        "label": "Change in Accounting Principle, Accounting Standards Update, Adoption Date",
        "terseLabel": "Change in accounting principle, accounting standards update, adoption date"
       }
      }
     },
     "localname": "ChangeInAccountingPrincipleAccountingStandardsUpdateAdoptionDate",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "dateItemType"
    },
    "us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateImmaterialEffect": {
     "auth_ref": [
      "r103",
      "r114",
      "r167",
      "r185",
      "r308",
      "r319"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicates (true false) whether effect from applying amendment to accounting standards is immaterial.",
        "label": "Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]",
        "terseLabel": "Change in accounting principle, accounting standards update, immaterial effect"
       }
      }
     },
     "localname": "ChangeInAccountingPrincipleAccountingStandardsUpdateImmaterialEffect",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "booleanItemType"
    },
    "us-gaap_ClassOfStockDomain": {
     "auth_ref": [
      "r92",
      "r94",
      "r116",
      "r117",
      "r118",
      "r120",
      "r122",
      "r128",
      "r129",
      "r130",
      "r177",
      "r213",
      "r217",
      "r218",
      "r219",
      "r222",
      "r223",
      "r234",
      "r235",
      "r239",
      "r243",
      "r363",
      "r522"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Share of stock differentiated by the voting rights the holder receives. Examples include, but are not limited to, common stock, redeemable preferred stock, nonredeemable preferred stock, and convertible stock.",
        "label": "Class of Stock [Domain]",
        "terseLabel": "Class of Stock"
       }
      }
     },
     "localname": "ClassOfStockDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ClassOfStockLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Class of Stock [Line Items]",
        "terseLabel": "Class Of Stock [Line Items]"
       }
      }
     },
     "localname": "ClassOfStockLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ClassOfWarrantOrRightAxis": {
     "auth_ref": [
      "r258",
      "r276"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of warrant or right issued.",
        "label": "Class of Warrant or Right [Axis]",
        "terseLabel": "Class of Warrant or Right"
       }
      }
     },
     "localname": "ClassOfWarrantOrRightAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ClassOfWarrantOrRightDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Name of the class or type of warrant or right outstanding. Warrants and rights represent derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months.",
        "label": "Class of Warrant or Right [Domain]",
        "terseLabel": "Class of Warrant or Right"
       }
      }
     },
     "localname": "ClassOfWarrantOrRightDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1": {
     "auth_ref": [
      "r251"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Exercise price per share or per unit of warrants or rights outstanding.",
        "label": "Class of Warrant or Right, Exercise Price of Warrants or Rights",
        "terseLabel": "Pre-funded warrant, exercise price"
       }
      }
     },
     "localname": "ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ClassOfWarrantOrRightLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Class of Warrant or Right [Line Items]",
        "terseLabel": "Class Of Warrant Or Right [Line Items]"
       }
      }
     },
     "localname": "ClassOfWarrantOrRightLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights": {
     "auth_ref": [
      "r251"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.",
        "label": "Class of Warrant or Right, Number of Securities Called by Warrants or Rights",
        "terseLabel": "Pre-funded warrants to purchase an additional shares of common stock",
        "verboseLabel": "Warrants to purchase an additional shares of common stock"
       }
      }
     },
     "localname": "ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ClassOfWarrantOrRightTable": {
     "auth_ref": [
      "r258",
      "r276"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure for warrants or rights issued, which includes the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.",
        "label": "Class of Warrant or Right [Table]",
        "terseLabel": "Class Of Warrant Or Right [Table]"
       }
      }
     },
     "localname": "ClassOfWarrantOrRightTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ClosedBlockDisclosureTextBlock": {
     "auth_ref": [
      "r484",
      "r485"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure pertaining to the closed block.",
        "label": "Closed Block Disclosure [Text Block]",
        "terseLabel": "Sanofi Agreement"
       }
      }
     },
     "localname": "ClosedBlockDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreement"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CollaborativeArrangementAccountingPolicy": {
     "auth_ref": [
      "r324"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for collaborative arrangements.",
        "label": "Collaborative Arrangement, Accounting Policy [Policy Text Block]",
        "terseLabel": "Collaborative Arrangements"
       }
      }
     },
     "localname": "CollaborativeArrangementAccountingPolicy",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CollaborativeArrangementDisclosureTextBlock": {
     "auth_ref": [
      "r322",
      "r323",
      "r327"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for collaborative arrangements in which the entity is a participant, including a) information about the nature and purpose of such arrangements; b) its rights and obligations thereunder; c) the accounting policy for collaborative arrangements; and d) the income statement classification and amounts attributable to transactions arising from the collaborative arrangement between participants.",
        "label": "Collaborative Arrangement Disclosure [Text Block]",
        "terseLabel": "License Agreements"
       }
      }
     },
     "localname": "CollaborativeArrangementDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreements"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]",
        "terseLabel": "Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]"
       }
      }
     },
     "localname": "CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CommercialPaperMember": {
     "auth_ref": [
      "r211"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Unsecured promissory note (generally negotiable) that provides institutions with short-term funds.",
        "label": "Commercial Paper [Member]",
        "terseLabel": "Commercial Paper"
       }
      }
     },
     "localname": "CommercialPaperMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommitmentsAndContingencies": {
     "auth_ref": [
      "r41",
      "r208",
      "r445",
      "r459"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_LiabilitiesAndStockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Represents the caption on the face of the balance sheet to indicate that the entity has entered into (1) purchase or supply arrangements that will require expending a portion of its resources to meet the terms thereof, and (2) is exposed to potential losses or, less frequently, gains, arising from (a) possible claims against a company's resources due to future performance under contract terms, and (b) possible losses or likely gains from uncertainties that will ultimately be resolved when one or more future events that are deemed likely to occur do occur or fail to occur.",
        "label": "Commitments and Contingencies",
        "terseLabel": "Commitments and contingencies"
       }
      }
     },
     "localname": "CommitmentsAndContingencies",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Commitments and Contingencies Disclosure [Abstract]"
       }
      }
     },
     "localname": "CommitmentsAndContingenciesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureTextBlock": {
     "auth_ref": [
      "r205",
      "r206",
      "r207",
      "r209",
      "r502"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for commitments and contingencies.",
        "label": "Commitments and Contingencies Disclosure [Text Block]",
        "terseLabel": "Commitments and Contingencies"
       }
      }
     },
     "localname": "CommitmentsAndContingenciesDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingencies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CommonStockCapitalSharesReservedForFutureIssuance": {
     "auth_ref": [
      "r43"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Aggregate number of common shares reserved for future issuance.",
        "label": "Common Stock, Capital Shares Reserved for Future Issuance",
        "terseLabel": "Shares reserved for issuance",
        "totalLabel": "Total"
       }
      }
     },
     "localname": "CommonStockCapitalSharesReservedForFutureIssuance",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityScheduleOfNumberOfCommonStockReservedForFutureIssuanceDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockMember": {
     "auth_ref": [
      "r99",
      "r100",
      "r351"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock that is subordinate to all other stock of the issuer.",
        "label": "Common Stock [Member]",
        "terseLabel": "Common Stock"
       }
      }
     },
     "localname": "CommonStockMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommonStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r20"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Face amount or stated value per share of common stock.",
        "label": "Common Stock, Par or Stated Value Per Share",
        "terseLabel": "Common stock, par value",
        "verboseLabel": "Common stock, par value"
       }
      }
     },
     "localname": "CommonStockParOrStatedValuePerShare",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CommonStockSharesAuthorized": {
     "auth_ref": [
      "r20"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The maximum number of common shares permitted to be issued by an entity's charter and bylaws.",
        "label": "Common Stock, Shares Authorized",
        "terseLabel": "Common stock, shares authorized",
        "verboseLabel": "Common stock, shares authorized"
       }
      }
     },
     "localname": "CommonStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesIssued": {
     "auth_ref": [
      "r20"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.",
        "label": "Common Stock, Shares, Issued",
        "terseLabel": "Common stock, shares issued",
        "totalLabel": "Common Stock, Shares, Issued, Total"
       }
      }
     },
     "localname": "CommonStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesOutstanding": {
     "auth_ref": [
      "r20",
      "r250"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.",
        "label": "Common Stock, Shares, Outstanding",
        "periodEndLabel": "Common Stock, Shares, Outstanding, Ending Balance",
        "periodStartLabel": "Common Stock, Shares, Outstanding, Beginning Balance",
        "terseLabel": "Common stock, shares outstanding"
       }
      }
     },
     "localname": "CommonStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockValue": {
     "auth_ref": [
      "r20",
      "r407"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_StockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Aggregate par or stated value of issued nonredeemable common stock (or common stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable common shares, par value and other disclosure concepts are in another section within stockholders' equity.",
        "label": "Common Stock, Value, Issued",
        "periodEndLabel": "Common Stock, Value, Issued, Ending Balance",
        "periodStartLabel": "Common Stock, Value, Issued, Beginning Balance",
        "terseLabel": "Common stock, value",
        "totalLabel": "Common Stock, Value, Issued, Total"
       }
      }
     },
     "localname": "CommonStockValue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CommonStockVotingRights": {
     "auth_ref": [
      "r251"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Description of voting rights of common stock. Includes eligibility to vote and votes per share owned. Include also, if any, unusual voting rights.",
        "label": "Common Stock, Voting Rights",
        "terseLabel": "Common stock, voting rights"
       }
      }
     },
     "localname": "CommonStockVotingRights",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ComprehensiveIncomeNetOfTax": {
     "auth_ref": [
      "r57",
      "r59",
      "r60",
      "r66",
      "r447",
      "r463"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveLossUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.",
        "label": "Comprehensive Income (Loss), Net of Tax, Attributable to Parent",
        "totalLabel": "Comprehensive loss"
       }
      }
     },
     "localname": "ComprehensiveIncomeNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveLossUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ComprehensiveIncomePolicyPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for comprehensive income.",
        "label": "Comprehensive Income, Policy [Policy Text Block]",
        "terseLabel": "Comprehensive Loss"
       }
      }
     },
     "localname": "ComprehensiveIncomePolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ConcentrationRiskCreditRisk": {
     "auth_ref": [
      "r133",
      "r452"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for credit risk.",
        "label": "Concentration Risk, Credit Risk, Policy [Policy Text Block]",
        "terseLabel": "Concentration of Credit Risk and Other Risks and Uncertainties"
       }
      }
     },
     "localname": "ConcentrationRiskCreditRisk",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ConsiderationReceivedForBeneficialInterestObtainedForTransferringFinancialAsset": {
     "auth_ref": [
      "r86"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of beneficial interest received as consideration for transferring noncash financial asset. Includes, but is not limited to, trade receivable in securitization transaction.",
        "label": "Consideration Received for Beneficial Interest Obtained for Transferring Financial Asset",
        "terseLabel": "Consideration received"
       }
      }
     },
     "localname": "ConsiderationReceivedForBeneficialInterestObtainedForTransferringFinancialAsset",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ConstructionInProgressMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.",
        "label": "Construction in Progress [Member]",
        "terseLabel": "Construction in Progress"
       }
      }
     },
     "localname": "ConstructionInProgressMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CorporateBondSecuritiesMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "This category includes information about long-term debt securities that are issued by either a domestic or foreign corporate business entity with a date certain promise of repayment and a return to the holder for the time value of money (for example, variable or fixed interest, original issue discount).",
        "label": "Corporate Bond Securities [Member]",
        "terseLabel": "Corporate Bonds"
       }
      }
     },
     "localname": "CorporateBondSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition": {
     "auth_ref": [
      "r175",
      "r189",
      "r190"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.",
        "label": "Debt Securities, Available-for-sale, Unrealized Loss Position",
        "terseLabel": "Unrealized loss position",
        "totalLabel": "Debt Securities, Available-for-sale, Unrealized Loss Position, Total"
       }
      }
     },
     "localname": "DebtSecuritiesAvailableForSaleUnrealizedLossPosition",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredIncomeCurrent": {
     "auth_ref": [
      "r210"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_LiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of deferred income excluding obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as current.",
        "label": "Deferred Income, Current",
        "terseLabel": "Deferred revenue"
       }
      }
     },
     "localname": "DeferredIncomeCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredIncomeNoncurrent": {
     "auth_ref": [
      "r210"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of deferred income excluding obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as noncurrent.",
        "label": "Deferred Income, Noncurrent",
        "terseLabel": "Deferred revenue, non-current"
       }
      }
     },
     "localname": "DeferredIncomeNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredRevenue": {
     "auth_ref": [
      "r27"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable.",
        "label": "Deferred Revenue",
        "totalLabel": "Deferred Revenue, Total"
       }
      }
     },
     "localname": "DeferredRevenue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredRevenueCurrent": {
     "auth_ref": [
      "r27"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as current.",
        "label": "Deferred Revenue, Current",
        "totalLabel": "Deferred Revenue, Current, Total"
       }
      }
     },
     "localname": "DeferredRevenueCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Depreciation": {
     "auth_ref": [
      "r81",
      "r198"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.",
        "label": "Depreciation",
        "terseLabel": "Depreciation",
        "totalLabel": "Depreciation, Total",
        "verboseLabel": "Depreciation expense"
       }
      }
     },
     "localname": "Depreciation",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock": {
     "auth_ref": [
      "r312"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for share-based payment arrangement.",
        "label": "Share-based Payment Arrangement [Text Block]",
        "terseLabel": "Stock-Based Compensation"
       }
      }
     },
     "localname": "DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensation"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Share-based Payment Arrangement [Abstract]"
       }
      }
     },
     "localname": "DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DividendsCommonStock": {
     "auth_ref": [
      "r257",
      "r451"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).",
        "label": "Dividends, Common Stock",
        "terseLabel": "Common stock, dividends declared",
        "totalLabel": "Dividends, Common Stock, Total"
       }
      }
     },
     "localname": "DividendsCommonStock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EarningsPerShareAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Earnings Per Share [Abstract]"
       }
      }
     },
     "localname": "EarningsPerShareAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_EarningsPerShareBasicAndDiluted": {
     "auth_ref": [
      "r121"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements.  Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period.  Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.",
        "label": "Earnings Per Share, Basic and Diluted",
        "terseLabel": "Net loss per share, basic and diluted",
        "totalLabel": "Earnings Per Share, Basic and Diluted, Total"
       }
      }
     },
     "localname": "EarningsPerShareBasicAndDiluted",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_EarningsPerSharePolicyTextBlock": {
     "auth_ref": [
      "r123",
      "r124"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for computing basic and diluted earnings or loss per share for each class of common stock and participating security. Addresses all significant policy factors, including any antidilutive items that have been excluded from the computation and takes into account stock dividends, splits and reverse splits that occur after the balance sheet date of the latest reporting period but before the issuance of the financial statements.",
        "label": "Earnings Per Share, Policy [Policy Text Block]",
        "terseLabel": "Net Loss Per Share"
       }
      }
     },
     "localname": "EarningsPerSharePolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_EarningsPerShareTextBlock": {
     "auth_ref": [
      "r123",
      "r124",
      "r125",
      "r126"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for earnings per share.",
        "label": "Earnings Per Share [Text Block]",
        "terseLabel": "Net Loss Per Share Attributable to Common Stockholders"
       }
      }
     },
     "localname": "EarningsPerShareTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholders"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]",
        "terseLabel": "Employee Service Share Based Compensation Allocation Of Recognized Period Costs Line Items"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1": {
     "auth_ref": [
      "r298"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.",
        "label": "Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition",
        "terseLabel": "Expects to recognize over a remaining weighted-average period"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions": {
     "auth_ref": [
      "r298"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.",
        "label": "Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount",
        "terseLabel": "Unrecognized stock-based compensation"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EmployeeStockOptionMember": {
     "auth_ref": [
      "r295"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Share-based payment arrangement granting right, subject to vesting and other restrictions, to purchase or sell certain number of shares at predetermined price for specified period of time.",
        "label": "Share-based Payment Arrangement, Option [Member]",
        "terseLabel": "Stock Options",
        "verboseLabel": "Stock Options"
       }
      }
     },
     "localname": "EmployeeStockOptionMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EquityComponentDomain": {
     "auth_ref": [
      "r2",
      "r61",
      "r62",
      "r63",
      "r99",
      "r100",
      "r101",
      "r104",
      "r111",
      "r113",
      "r127",
      "r184",
      "r250",
      "r257",
      "r305",
      "r306",
      "r307",
      "r317",
      "r318",
      "r351",
      "r374",
      "r375",
      "r376",
      "r377",
      "r378",
      "r379",
      "r473",
      "r474",
      "r475",
      "r529"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Components of equity are the parts of the total Equity balance including that which is allocated to common, preferred, treasury stock, retained earnings, etc.",
        "label": "Equity Component [Domain]",
        "terseLabel": "Equity Component"
       }
      }
     },
     "localname": "EquityComponentDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ExcessStockSharesIssued": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of excess stock shares of an entity that have been sold or granted to shareholders.",
        "label": "Excess Stock, Shares Issued",
        "terseLabel": "Additional shares issued"
       }
      }
     },
     "localname": "ExcessStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ExchangeTradedOptionsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Contracts conveying rights, but not obligations, to buy or sell a specific or standard commodity, or financial or equity instrument, at a specified price during a specified period (an American option) or at a specified date (a European option), which are traded on a stock exchange.",
        "label": "Exchange Traded Options [Member]",
        "terseLabel": "Stock options"
       }
      }
     },
     "localname": "ExchangeTradedOptionsMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]",
        "terseLabel": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable": {
     "auth_ref": [
      "r354",
      "r355",
      "r356",
      "r361"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about asset and liability measured at fair value on recurring and nonrecurring basis.",
        "label": "Fair Value, Recurring and Nonrecurring [Table]",
        "terseLabel": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table]"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnRecurringBasisTextBlock": {
     "auth_ref": [
      "r354",
      "r355"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).",
        "label": "Fair Value, Assets Measured on Recurring Basis [Table Text Block]",
        "terseLabel": "Summary of Investments Measured and Recognized at Fair Value"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnRecurringBasisTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain": {
     "auth_ref": [
      "r359"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Class of asset.",
        "label": "Asset Class [Domain]",
        "terseLabel": "Asset Class"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueByAssetClassAxis": {
     "auth_ref": [
      "r354",
      "r361"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by class of asset.",
        "label": "Asset Class [Axis]",
        "terseLabel": "Asset Class"
       }
      }
     },
     "localname": "FairValueByAssetClassAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByFairValueHierarchyLevelAxis": {
     "auth_ref": [
      "r226",
      "r228",
      "r229",
      "r264",
      "r265",
      "r266",
      "r267",
      "r268",
      "r269",
      "r270",
      "r272",
      "r355",
      "r411",
      "r412",
      "r413"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by level within fair value hierarchy and fair value measured at net asset value per share as practical expedient.",
        "label": "Fair Value Hierarchy and NAV [Axis]",
        "terseLabel": "Fair Value Hierarchy and NAV"
       }
      }
     },
     "localname": "FairValueByFairValueHierarchyLevelAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByMeasurementFrequencyAxis": {
     "auth_ref": [
      "r354",
      "r355",
      "r357",
      "r358",
      "r362"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by measurement frequency.",
        "label": "Measurement Frequency [Axis]",
        "terseLabel": "Measurement Frequency"
       }
      }
     },
     "localname": "FairValueByMeasurementFrequencyAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosuresAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Fair Value Disclosures [Abstract]"
       }
      }
     },
     "localname": "FairValueDisclosuresAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosuresTextBlock": {
     "auth_ref": [
      "r360"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.",
        "label": "Fair Value Disclosures [Text Block]",
        "terseLabel": "Fair Value Measurement"
       }
      }
     },
     "localname": "FairValueDisclosuresTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurement"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueInputsLevel1Member": {
     "auth_ref": [
      "r226",
      "r264",
      "r265",
      "r270",
      "r272",
      "r355",
      "r411"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Quoted prices in active markets for identical assets or liabilities that the reporting entity can access at the measurement date.",
        "label": "Fair Value, Inputs, Level 1 [Member]",
        "terseLabel": "Level 1"
       }
      }
     },
     "localname": "FairValueInputsLevel1Member",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel2Member": {
     "auth_ref": [
      "r226",
      "r228",
      "r229",
      "r264",
      "r265",
      "r270",
      "r272",
      "r355",
      "r412"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Inputs other than quoted prices included within level 1 that are observable for an asset or liability, either directly or indirectly, including, but not limited to, quoted prices for similar assets or liabilities in active markets, or quoted prices for identical or similar assets or liabilities in inactive markets.",
        "label": "Fair Value, Inputs, Level 2 [Member]",
        "terseLabel": "Level 2"
       }
      }
     },
     "localname": "FairValueInputsLevel2Member",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementFrequencyDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Measurement frequency.",
        "label": "Measurement Frequency [Domain]",
        "terseLabel": "Measurement Frequency"
       }
      }
     },
     "localname": "FairValueMeasurementFrequencyDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementPolicyPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for fair value measurements of financial and non-financial assets, liabilities and instruments classified in shareholders' equity. Disclosures include, but are not limited to, how an entity that manages a group of financial assets and liabilities on the basis of its net exposure measures the fair value of those assets and liabilities.",
        "label": "Fair Value Measurement, Policy [Policy Text Block]",
        "terseLabel": "Fair Value Measurement"
       }
      }
     },
     "localname": "FairValueMeasurementPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueMeasurementsFairValueHierarchyDomain": {
     "auth_ref": [
      "r226",
      "r228",
      "r229",
      "r264",
      "r265",
      "r266",
      "r267",
      "r268",
      "r269",
      "r270",
      "r272",
      "r411",
      "r412",
      "r413"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Categories used to prioritize the inputs to valuation techniques to measure fair value.",
        "label": "Fair Value Hierarchy and NAV [Domain]",
        "terseLabel": "Fair Value Hierarchy and NAV"
       }
      }
     },
     "localname": "FairValueMeasurementsFairValueHierarchyDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementsRecurringMember": {
     "auth_ref": [
      "r360",
      "r362"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Frequent fair value measurement. Includes, but is not limited to, fair value adjustment for impairment of asset, liability or equity, frequently measured at fair value.",
        "label": "Fair Value, Recurring [Member]",
        "terseLabel": "Fair Value, Recurring"
       }
      }
     },
     "localname": "FairValueMeasurementsRecurringMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfContractualMaturitiesOfInvestmentsDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis": {
     "auth_ref": [
      "r191",
      "r192",
      "r194",
      "r195",
      "r423",
      "r427"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by major type or class of finite-lived intangible assets.",
        "label": "Finite-Lived Intangible Assets by Major Class [Axis]",
        "terseLabel": "Finite-Lived Intangible Assets by Major Class"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsByMajorClassAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain": {
     "auth_ref": [
      "r191",
      "r193"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The major class of finite-lived intangible asset (for example, patents, trademarks, copyrights, etc.) A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.",
        "label": "Finite-Lived Intangible Assets, Major Class Name [Domain]",
        "terseLabel": "Finite-Lived Intangible Assets, Major Class Name"
       }
      }
     },
     "localname": "FiniteLivedIntangibleAssetsMajorClassNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_GeneralAndAdministrativeExpense": {
     "auth_ref": [
      "r68"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_OperatingExpenses",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.",
        "label": "General and Administrative Expense",
        "terseLabel": "General and administrative",
        "totalLabel": "General and Administrative Expense, Total"
       }
      }
     },
     "localname": "GeneralAndAdministrativeExpense",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GeneralAndAdministrativeExpenseMember": {
     "auth_ref": [
      "r67"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Primary financial statement caption encompassing general and administrative expense.",
        "label": "General and Administrative Expense [Member]",
        "terseLabel": "General And Administrative",
        "verboseLabel": "General And Administrative"
       }
      }
     },
     "localname": "GeneralAndAdministrativeExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf": {
     "auth_ref": [
      "r81",
      "r197"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.",
        "label": "Impairment of Long-Lived Assets to be Disposed of",
        "terseLabel": "Impairment of long-lived assets"
       }
      }
     },
     "localname": "ImpairmentOfLongLivedAssetsToBeDisposedOf",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock": {
     "auth_ref": [
      "r196",
      "r203"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for recognizing and measuring the impairment of long-lived assets. An entity also may disclose its accounting policy for long-lived assets to be sold. This policy excludes goodwill and intangible assets.",
        "label": "Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]",
        "terseLabel": "Impairment of Long-Lived Assets"
       }
      }
     },
     "localname": "ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_InProcessResearchAndDevelopmentPolicy": {
     "auth_ref": [
      "r34",
      "r314"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for costs assigned to identifiable tangible and intangible assets of an acquired entity to be used in the research and development activities of the combined enterprise. An entity also may disclose the appraisal method or significant assumptions used to value acquired research and development assets.",
        "label": "In Process Research and Development, Policy [Policy Text Block]",
        "terseLabel": "Acquired In-Process Research and Development Expenses"
       }
      }
     },
     "localname": "InProcessResearchAndDevelopmentPolicy",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_IncomeStatementAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Income Statement [Abstract]"
       }
      }
     },
     "localname": "IncomeStatementAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementLocationAxis": {
     "auth_ref": [
      "r202",
      "r204"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by location in the income statement.",
        "label": "Income Statement Location [Axis]",
        "terseLabel": "Income Statement Location"
       }
      }
     },
     "localname": "IncomeStatementLocationAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementLocationDomain": {
     "auth_ref": [
      "r204"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Location in the income statement.",
        "label": "Income Statement Location [Domain]",
        "terseLabel": "Income Statement Location"
       }
      }
     },
     "localname": "IncomeStatementLocationDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncreaseDecreaseInAccountsPayable": {
     "auth_ref": [
      "r80"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 9.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The increase (decrease) during the reporting period in the aggregate amount of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business.",
        "label": "Increase (Decrease) in Accounts Payable",
        "terseLabel": "Accounts payable",
        "totalLabel": "Increase (Decrease) in Accounts Payable, Total"
       }
      }
     },
     "localname": "IncreaseDecreaseInAccountsPayable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInAccruedLiabilities": {
     "auth_ref": [
      "r80"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 10.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The increase (decrease) during the reporting period in the aggregate amount of expenses incurred but not yet paid.",
        "label": "Increase (Decrease) in Accrued Liabilities",
        "terseLabel": "Accrued liabilities",
        "totalLabel": "Increase (Decrease) in Accrued Liabilities, Total"
       }
      }
     },
     "localname": "IncreaseDecreaseInAccruedLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInDeferredRevenue": {
     "auth_ref": [
      "r80"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 11.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of increase (decrease) in deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable.",
        "label": "Increase (Decrease) in Deferred Revenue",
        "terseLabel": "Deferred Revenue"
       }
      }
     },
     "localname": "IncreaseDecreaseInDeferredRevenue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInOperatingCapitalAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Increase (Decrease) in Operating Capital [Abstract]",
        "terseLabel": "Changes in assets and liabilities:"
       }
      }
     },
     "localname": "IncreaseDecreaseInOperatingCapitalAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncreaseDecreaseInOtherOperatingAssets": {
     "auth_ref": [
      "r80"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 7.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of increase (decrease) in operating assets classified as other.",
        "label": "Increase (Decrease) in Other Operating Assets",
        "negatedLabel": "Other non-current assets",
        "totalLabel": "Increase (Decrease) in Other Operating Assets, Total"
       }
      }
     },
     "localname": "IncreaseDecreaseInOtherOperatingAssets",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets": {
     "auth_ref": [
      "r80"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 6.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of increase (decrease) in prepaid expenses, and assets classified as other.",
        "label": "Increase (Decrease) in Prepaid Expense and Other Assets",
        "negatedLabel": "Prepaid expenses and other current assets",
        "totalLabel": "Increase (Decrease) in Prepaid Expense and Other Assets, Total"
       }
      }
     },
     "localname": "IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInPrepaidRent": {
     "auth_ref": [
      "r80"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of increase (decrease) of consideration paid in advance for rent that provides economic benefits in future periods.",
        "label": "Increase (Decrease) in Prepaid Rent",
        "terseLabel": "Total future rent payments"
       }
      }
     },
     "localname": "IncreaseDecreaseInPrepaidRent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InvestmentPolicyTextBlock": {
     "auth_ref": [
      "r176",
      "r464"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for investment in financial asset.",
        "label": "Investment, Policy [Policy Text Block]",
        "terseLabel": "Investments"
       }
      }
     },
     "localname": "InvestmentPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_InvestmentTypeAxis": {
     "auth_ref": [
      "r486",
      "r487",
      "r488",
      "r489",
      "r490",
      "r491",
      "r492",
      "r493",
      "r494",
      "r495",
      "r496",
      "r497",
      "r498",
      "r499",
      "r500"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of investments.",
        "label": "Investment Type [Axis]",
        "terseLabel": "Investment Type"
       }
      }
     },
     "localname": "InvestmentTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InvestmentTypeCategorizationMember": {
     "auth_ref": [
      "r486",
      "r487",
      "r488",
      "r489",
      "r490",
      "r491",
      "r492",
      "r493",
      "r494",
      "r495",
      "r496",
      "r497",
      "r498",
      "r499",
      "r500"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Asset obtained to generate income or appreciate in value.",
        "label": "Investments [Domain]",
        "terseLabel": "Investments"
       }
      }
     },
     "localname": "InvestmentTypeCategorizationMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InvestmentsAndCash": {
     "auth_ref": [
      "r460"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sum of investments and unrestricted cash as of the balance sheet date.",
        "label": "Investments and Cash",
        "terseLabel": "Cash, and investments",
        "totalLabel": "Investments and Cash, Total"
       }
      }
     },
     "localname": "InvestmentsAndCash",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments.",
        "label": "Investments Classified by Contractual Maturity Date [Table Text Block]",
        "terseLabel": "Summary of Contractual Maturities of Investments"
       }
      }
     },
     "localname": "InvestmentsClassifiedByContractualMaturityDateTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_InvestorMember": {
     "auth_ref": [
      "r398",
      "r399"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Business entity or individual that puts money, by purchase or expenditure, in something offering potential profitable returns, such as interest income or appreciation in value.",
        "label": "Investor [Member]",
        "terseLabel": "Topse Holding A/S"
       }
      }
     },
     "localname": "InvestorMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LeaseAgreementsMember": {
     "auth_ref": [
      "r320"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Contractual agreement that stipulates the lessee pay the lessor for use of an asset.",
        "label": "Lease Agreements [Member]",
        "terseLabel": "Lease Agreements [Member]"
       }
      }
     },
     "localname": "LeaseAgreementsMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LeaseholdImprovementsMember": {
     "auth_ref": [
      "r199"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Additions or improvements to assets held under a lease arrangement.",
        "label": "Leasehold Improvements [Member]",
        "terseLabel": "Leasehold Improvements"
       }
      }
     },
     "localname": "LeaseholdImprovementsMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LesseeLeaseDescriptionLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Lessee, Lease, Description [Line Items]",
        "terseLabel": "Lessee Lease Description [Line Items]"
       }
      }
     },
     "localname": "LesseeLeaseDescriptionLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LesseeLeaseDescriptionTable": {
     "auth_ref": [
      "r386"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about lessee's leases.",
        "label": "Lessee, Lease, Description [Table]",
        "terseLabel": "Lessee Lease Description [Table]"
       }
      }
     },
     "localname": "LesseeLeaseDescriptionTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LesseeLeasesPolicyTextBlock": {
     "auth_ref": [
      "r385"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for leasing arrangement entered into by lessee.",
        "label": "Lessee, Leases [Policy Text Block]",
        "terseLabel": "Leases"
       }
      }
     },
     "localname": "LesseeLeasesPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock": {
     "auth_ref": [
      "r393"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of undiscounted cash flows of lessee's operating lease liability. Includes, but is not limited to, reconciliation of undiscounted cash flows to operating lease liability recognized in statement of financial position.",
        "label": "Lessee, Operating Lease, Liability, Maturity [Table Text Block]",
        "terseLabel": "Schedule of Maturities of Lease Liabilities"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue": {
     "auth_ref": [
      "r393"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails2": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payment for operating lease.",
        "label": "Lessee, Operating Lease, Liability, to be Paid",
        "totalLabel": "Total future undiscounted lease payments"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths": {
     "auth_ref": [
      "r393"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).",
        "label": "Lessee, Operating Lease, Liability, to be Paid, Year One",
        "terseLabel": "2023"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour": {
     "auth_ref": [
      "r393"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails": {
       "order": 4.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).",
        "label": "Lessee, Operating Lease, Liability, to be Paid, Year Four",
        "terseLabel": "2026"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueYearFour",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree": {
     "auth_ref": [
      "r393"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).",
        "label": "Lessee, Operating Lease, Liability, to be Paid, Year Three",
        "terseLabel": "2025"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueYearThree",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo": {
     "auth_ref": [
      "r393"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).",
        "label": "Lessee, Operating Lease, Liability, to be Paid, Year Two",
        "terseLabel": "2024"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueYearTwo",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear": {
     "auth_ref": [
      "r393"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails": {
       "order": 0.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payment for operating lease having initial or remaining lease term in excess of one year to be paid in remainder of current fiscal year.",
        "label": "Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year",
        "terseLabel": "2022 (remaining three months)"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount": {
     "auth_ref": [
      "r393"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails2": {
       "order": 0.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.",
        "label": "Lessee, Operating Lease, Liability, Undiscounted Excess Amount",
        "negatedLabel": "Less imputed interest"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityUndiscountedExcessAmount",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Liabilities": {
     "auth_ref": [
      "r37",
      "r94",
      "r152",
      "r177",
      "r213",
      "r214",
      "r215",
      "r217",
      "r218",
      "r219",
      "r220",
      "r221",
      "r222",
      "r223",
      "r330",
      "r334",
      "r335",
      "r363",
      "r405",
      "r406"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_LiabilitiesAndStockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.",
        "label": "Liabilities",
        "totalLabel": "Total liabilities"
       }
      }
     },
     "localname": "Liabilities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesAndStockholdersEquity": {
     "auth_ref": [
      "r26",
      "r94",
      "r177",
      "r363",
      "r407",
      "r442",
      "r457"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of liabilities and equity items, including the portion of equity attributable to noncontrolling interests, if any.",
        "label": "Liabilities and Equity",
        "totalLabel": "Total liabilities and stockholders\u2019 equity"
       }
      }
     },
     "localname": "LiabilitiesAndStockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesAndStockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Liabilities and Equity [Abstract]",
        "terseLabel": "Liabilities and stockholders\u2019 equity"
       }
      }
     },
     "localname": "LiabilitiesAndStockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LiabilitiesCurrent": {
     "auth_ref": [
      "r40",
      "r94",
      "r177",
      "r213",
      "r214",
      "r215",
      "r217",
      "r218",
      "r219",
      "r220",
      "r221",
      "r222",
      "r223",
      "r330",
      "r334",
      "r335",
      "r363",
      "r405",
      "r406",
      "r407"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Total obligations incurred as part of normal operations that are expected to be paid during the following twelve months or within one business cycle, if longer.",
        "label": "Liabilities, Current",
        "totalLabel": "Total current liabilities"
       }
      }
     },
     "localname": "LiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesCurrentAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Liabilities, Current [Abstract]",
        "terseLabel": "Current liabilities:"
       }
      }
     },
     "localname": "LiabilitiesCurrentAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_MarketableSecuritiesCurrent": {
     "auth_ref": [
      "r9",
      "r38"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_AssetsCurrent",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of investment in marketable security, classified as current.",
        "label": "Marketable Securities, Current",
        "terseLabel": "Marketable securities",
        "totalLabel": "Marketable Securities, Current, Total"
       }
      }
     },
     "localname": "MarketableSecuritiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_MoneyMarketFundsMember": {
     "auth_ref": [
      "r264"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Fund that invests in short-term money-market instruments, for example, but not limited to, commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and other highly liquid securities.",
        "label": "Money Market Funds [Member]",
        "terseLabel": "Money Market Funds"
       }
      }
     },
     "localname": "MoneyMarketFundsMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivities": {
     "auth_ref": [
      "r78"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.",
        "label": "Net Cash Provided by (Used in) Financing Activities",
        "totalLabel": "Net cash provided by (used in) financing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Net Cash Provided by (Used in) Financing Activities [Abstract]",
        "terseLabel": "Cash flows from financing activities:"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivities": {
     "auth_ref": [
      "r78"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.",
        "label": "Net Cash Provided by (Used in) Investing Activities",
        "totalLabel": "Net cash (used in) provided by investing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Net Cash Provided by (Used in) Investing Activities [Abstract]",
        "terseLabel": "Cash flows from investing activities:"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivities": {
     "auth_ref": [
      "r78",
      "r79",
      "r82"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.",
        "label": "Net Cash Provided by (Used in) Operating Activities",
        "totalLabel": "Net cash provided by (used in) operating activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Net Cash Provided by (Used in) Operating Activities [Abstract]",
        "terseLabel": "Cash flows from operating activities:"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetIncomeLoss": {
     "auth_ref": [
      "r6",
      "r56",
      "r58",
      "r63",
      "r65",
      "r82",
      "r94",
      "r103",
      "r107",
      "r108",
      "r109",
      "r110",
      "r112",
      "r113",
      "r119",
      "r142",
      "r150",
      "r153",
      "r156",
      "r158",
      "r177",
      "r213",
      "r214",
      "r215",
      "r217",
      "r218",
      "r219",
      "r220",
      "r221",
      "r222",
      "r223",
      "r353",
      "r363",
      "r446",
      "r462"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveLossUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      },
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.",
        "label": "Net Income (Loss) Attributable to Parent",
        "terseLabel": "Net loss",
        "totalLabel": "Net loss"
       }
      }
     },
     "localname": "NetIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveLossUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy pertaining to new accounting pronouncements that may impact the entity's financial reporting. Includes, but is not limited to, quantification of the expected or actual impact.",
        "label": "New Accounting Pronouncements, Policy [Policy Text Block]",
        "terseLabel": "Recently Adopted Accounting Standards and Accounting Pronouncements"
       }
      }
     },
     "localname": "NewAccountingPronouncementsPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_NonoperatingIncomeExpense": {
     "auth_ref": [
      "r69"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business).",
        "label": "Nonoperating Income (Expense)",
        "terseLabel": "Other income, net",
        "totalLabel": "Nonoperating Income (Expense), Total"
       }
      }
     },
     "localname": "NonoperatingIncomeExpense",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NonvotingCommonStockMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Common stock securities that do not empower a holder to vote on corporate resolutions or the election of directors.",
        "label": "Nonvoting Common Stock [Member]",
        "terseLabel": "Non-voting Common Stock"
       }
      }
     },
     "localname": "NonvotingCommonStockMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NumberOfOperatingSegments": {
     "auth_ref": [
      "r139"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.",
        "label": "Number of Operating Segments",
        "terseLabel": "Number of operating segment"
       }
      }
     },
     "localname": "NumberOfOperatingSegments",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "us-gaap_OfficeEquipmentMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tangible personal property used in an office setting. Examples include, but are not limited to, computers, copiers and fax machine.",
        "label": "Office Equipment [Member]",
        "terseLabel": "Office Equipment"
       }
      }
     },
     "localname": "OfficeEquipmentMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OperatingExpenses": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_OperatingIncomeLoss",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.",
        "label": "Operating Expenses",
        "totalLabel": "Total operating expenses"
       }
      }
     },
     "localname": "OperatingExpenses",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingExpensesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Operating Expenses [Abstract]",
        "terseLabel": "Operating expenses:"
       }
      }
     },
     "localname": "OperatingExpensesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OperatingIncomeLoss": {
     "auth_ref": [
      "r142",
      "r150",
      "r153",
      "r156",
      "r158"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The net result for the period of deducting operating expenses from operating revenues.",
        "label": "Operating Income (Loss)",
        "terseLabel": "Loss from operations",
        "totalLabel": "Loss from operations"
       }
      }
     },
     "localname": "OperatingIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseCost": {
     "auth_ref": [
      "r387",
      "r394"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.",
        "label": "Operating Lease, Cost",
        "terseLabel": "Operating lease cost"
       }
      }
     },
     "localname": "OperatingLeaseCost",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfROUAssetsAndRelatedLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Lessee, Operating Lease, Liability, Payment, Due [Abstract]"
       }
      }
     },
     "localname": "OperatingLeaseLiabilitiesPaymentsDueAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_OperatingLeaseLiability": {
     "auth_ref": [
      "r383"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails2": {
       "order": 1.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Present value of lessee's discounted obligation for lease payments from operating lease.",
        "label": "Operating Lease, Liability",
        "terseLabel": "Total lease liabilities",
        "totalLabel": "Operating Lease, Liability, Total"
       }
      }
     },
     "localname": "OperatingLeaseLiability",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfMaturitiesOfLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLiabilityCurrent": {
     "auth_ref": [
      "r383"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_LiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.",
        "label": "Operating Lease, Liability, Current",
        "terseLabel": "Lease liabilities",
        "verboseLabel": "Current operating lease liabilities"
       }
      }
     },
     "localname": "OperatingLeaseLiabilityCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfROUAssetsAndRelatedLeaseLiabilitiesDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLiabilityNoncurrent": {
     "auth_ref": [
      "r383"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent.",
        "label": "Operating Lease, Liability, Noncurrent",
        "terseLabel": "Lease liabilities, non-current",
        "verboseLabel": "Non-current operating lease liabilities"
       }
      }
     },
     "localname": "OperatingLeaseLiabilityNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfROUAssetsAndRelatedLeaseLiabilitiesDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeasePayments": {
     "auth_ref": [
      "r384",
      "r389"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.",
        "label": "Operating Lease, Payments",
        "terseLabel": "Cash paid for operating lease liabilities"
       }
      }
     },
     "localname": "OperatingLeasePayments",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfROUAssetsAndRelatedLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseRightOfUseAsset": {
     "auth_ref": [
      "r382"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of lessee's right to use underlying asset under operating lease.",
        "label": "Operating Lease, Right-of-Use Asset",
        "verboseLabel": "Operating lease right-of-use assets"
       }
      }
     },
     "localname": "OperatingLeaseRightOfUseAsset",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent": {
     "auth_ref": [
      "r392",
      "r394"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average discount rate for operating lease calculated at point in time.",
        "label": "Operating Lease, Weighted Average Discount Rate, Percent",
        "terseLabel": "Weighted average discount rate"
       }
      }
     },
     "localname": "OperatingLeaseWeightedAverageDiscountRatePercent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfROUAssetsAndRelatedLeaseLiabilitiesDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1": {
     "auth_ref": [
      "r391",
      "r394"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.",
        "label": "Operating Lease, Weighted Average Remaining Lease Term",
        "terseLabel": "Weighted average remaining lease term (in years)"
       }
      }
     },
     "localname": "OperatingLeaseWeightedAverageRemainingLeaseTerm1",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfROUAssetsAndRelatedLeaseLiabilitiesDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_OptionIndexedToIssuersEquityTypeAxis": {
     "auth_ref": [
      "r230",
      "r340",
      "r341",
      "r342"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of freestanding contracts issued by an entity that are indexed to, and potentially settled in, an entity's own stock.",
        "label": "Option Indexed to Issuer's Equity, Type [Axis]"
       }
      }
     },
     "localname": "OptionIndexedToIssuersEquityTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OptionIndexedToIssuersEquityTypeDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Description of the type of freestanding contract issued by a Company that is indexed to, and potentially settled in, a Company's own stock. Specifically, the pertinent rights and privileges of the securities outstanding.",
        "label": "Option Indexed to Issuer's Equity, Type [Domain]"
       }
      }
     },
     "localname": "OptionIndexedToIssuersEquityTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Organization, Consolidation and Presentation of Financial Statements [Abstract]"
       }
      }
     },
     "localname": "OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock": {
     "auth_ref": [
      "r7",
      "r338"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.",
        "label": "Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]",
        "terseLabel": "Organization"
       }
      }
     },
     "localname": "OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganization"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_OtherAccruedLiabilitiesCurrent": {
     "auth_ref": [
      "r12",
      "r13",
      "r14",
      "r39"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails": {
       "order": 4.0,
       "parentTag": "us-gaap_AccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.",
        "label": "Other Accrued Liabilities, Current",
        "terseLabel": "Other"
       }
      }
     },
     "localname": "OtherAccruedLiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherAssetsNoncurrent": {
     "auth_ref": [
      "r35"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of noncurrent assets classified as other.",
        "label": "Other Assets, Noncurrent",
        "terseLabel": "Other non-current assets",
        "totalLabel": "Other Assets, Noncurrent, Total"
       }
      }
     },
     "localname": "OtherAssetsNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Other Comprehensive Income (Loss), Net of Tax [Abstract]",
        "terseLabel": "Other comprehensive loss:"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveLossUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax": {
     "auth_ref": [
      "r51",
      "r53"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveLossUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount, after tax and before adjustment, of unrealized holding gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Excludes unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.",
        "label": "OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax",
        "terseLabel": "Unrealized loss on marketable securities",
        "verboseLabel": "Unrealized (loss) gain on investments"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveLossUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherUnderwritingExpense": {
     "auth_ref": [
      "r465",
      "r483"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Costs incurred during the period, such as those relating to general administration and policy maintenance that do not vary with and are not primarily related to the acquisition or renewal of insurance contracts.",
        "label": "Other Underwriting Expense",
        "terseLabel": "Underwriting discounts and commissions costs"
       }
      }
     },
     "localname": "OtherUnderwritingExpense",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsOfStockIssuanceCosts": {
     "auth_ref": [
      "r76"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash outflow for cost incurred directly with the issuance of an equity security.",
        "label": "Payments of Stock Issuance Costs",
        "terseLabel": "Offering costs"
       }
      }
     },
     "localname": "PaymentsOfStockIssuanceCosts",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation": {
     "auth_ref": [
      "r75"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash outflow to satisfy grantee's tax withholding obligation for award under share-based payment arrangement.",
        "label": "Payment, Tax Withholding, Share-based Payment Arrangement",
        "negatedLabel": "Payment of employee taxes and exercise costs for shares withheld"
       }
      }
     },
     "localname": "PaymentsRelatedToTaxWithholdingForShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt": {
     "auth_ref": [
      "r70",
      "r72",
      "r169"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash outflow to acquire investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Payments to Acquire Debt Securities, Available-for-sale",
        "negatedLabel": "Purchases of marketable securities"
       }
      }
     },
     "localname": "PaymentsToAcquireAvailableForSaleSecuritiesDebt",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquirePropertyPlantAndEquipment": {
     "auth_ref": [
      "r73"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.",
        "label": "Payments to Acquire Property, Plant, and Equipment",
        "negatedLabel": "Purchase of property, plant and equipment",
        "totalLabel": "Payments to Acquire Property, Plant, and Equipment, Total"
       }
      }
     },
     "localname": "PaymentsToAcquirePropertyPlantAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PlanNameAxis": {
     "auth_ref": [
      "r278",
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by plan name for share-based payment arrangement.",
        "label": "Plan Name [Axis]",
        "terseLabel": "Plan Name"
       }
      }
     },
     "localname": "PlanNameAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PlanNameDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Plan name for share-based payment arrangement.",
        "label": "Plan Name [Domain]",
        "terseLabel": "Plan Name"
       }
      }
     },
     "localname": "PlanNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PreferredStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r19",
      "r234"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.",
        "label": "Preferred Stock, Par or Stated Value Per Share",
        "verboseLabel": "Preferred stock, par value"
       }
      }
     },
     "localname": "PreferredStockParOrStatedValuePerShare",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_PreferredStockSharesAuthorized": {
     "auth_ref": [
      "r19"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.",
        "label": "Preferred Stock, Shares Authorized",
        "verboseLabel": "Preferred stock, shares authorized"
       }
      }
     },
     "localname": "PreferredStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesIssued": {
     "auth_ref": [
      "r19",
      "r234"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.",
        "label": "Preferred Stock, Shares Issued",
        "terseLabel": "Preferred Stock, shares Issued",
        "totalLabel": "Preferred Stock, Shares Issued, Total"
       }
      }
     },
     "localname": "PreferredStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesOutstanding": {
     "auth_ref": [
      "r19"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.",
        "label": "Preferred Stock, Shares Outstanding",
        "periodEndLabel": "Preferred Stock, Shares Outstanding, Ending Balance",
        "periodStartLabel": "Preferred Stock, Shares Outstanding, Beginning Balance",
        "terseLabel": "Preferred Stock, shares outstanding"
       }
      }
     },
     "localname": "PreferredStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockValue": {
     "auth_ref": [
      "r19",
      "r407"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_StockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Aggregate par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.",
        "label": "Preferred Stock, Value, Issued",
        "periodEndLabel": "Preferred Stock, Value, Issued, Ending Balance",
        "periodStartLabel": "Preferred Stock, Value, Issued, Beginning Balance",
        "terseLabel": "Preferred stock, $0.01 par value; 200,000,000 shares authorized; no shares issued and outstanding",
        "totalLabel": "Preferred Stock, Value, Issued, Total"
       }
      }
     },
     "localname": "PreferredStockValue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PrepaidExpenseAndOtherAssetsCurrent": {
     "auth_ref": [
      "r10",
      "r28",
      "r29"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_AssetsCurrent",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.",
        "label": "Prepaid Expense and Other Assets, Current",
        "terseLabel": "Prepaid expenses and other current assets"
       }
      }
     },
     "localname": "PrepaidExpenseAndOtherAssetsCurrent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PriorPeriodReclassificationAdjustmentDescription": {
     "auth_ref": [
      "r5"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for reclassification affecting comparability of financial statement. Excludes amendment to accounting standards, other change in accounting principle, and correction of error.",
        "label": "Reclassification, Comparability Adjustment [Policy Text Block]",
        "terseLabel": "Reclassification"
       }
      }
     },
     "localname": "PriorPeriodReclassificationAdjustmentDescription",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ProceedsFromIssuanceOfCommonStock": {
     "auth_ref": [
      "r74"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash inflow from the additional capital contribution to the entity.",
        "label": "Proceeds from Issuance of Common Stock",
        "terseLabel": "Proceeds from common stock issuance",
        "verboseLabel": "Proceeds from issuance of common stock in public offering, net of offering costs"
       }
      }
     },
     "localname": "ProceedsFromIssuanceOfCommonStock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities": {
     "auth_ref": [
      "r70",
      "r71",
      "r169"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash inflow from sale, maturity, prepayment and call of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).",
        "label": "Proceeds from Sale and Maturity of Debt Securities, Available-for-sale",
        "terseLabel": "Proceeds from maturities of marketable securities",
        "totalLabel": "Proceeds from Sale and Maturity of Debt Securities, Available-for-sale, Total"
       }
      }
     },
     "localname": "ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities": {
     "auth_ref": [],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 3.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities  (held-to-maturity or available-for-sale) during the period.",
        "label": "Proceeds from Sale and Maturity of Marketable Securities",
        "terseLabel": "Proceeds from the sales of marketable securities",
        "totalLabel": "Proceeds from Sale and Maturity of Marketable Securities, Total"
       }
      }
     },
     "localname": "ProceedsFromSaleAndMaturityOfMarketableSecurities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromStockOptionsExercised": {
     "auth_ref": [
      "r74",
      "r300"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash inflow from exercise of option under share-based payment arrangement.",
        "label": "Proceeds from Stock Options Exercised",
        "terseLabel": "Proceeds from exercise of stock options"
       }
      }
     },
     "localname": "ProceedsFromStockOptionsExercised",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromStockPlans": {
     "auth_ref": [
      "r74"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash inflow associated with the amount received from the stock plan during the period.",
        "label": "Proceeds from Stock Plans",
        "terseLabel": "Proceeds from purchases under the employee stock purchase plan"
       }
      }
     },
     "localname": "ProceedsFromStockPlans",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProfitLoss": {
     "auth_ref": [
      "r6",
      "r56",
      "r58",
      "r63",
      "r77",
      "r94",
      "r103",
      "r112",
      "r113",
      "r142",
      "r150",
      "r153",
      "r156",
      "r158",
      "r177",
      "r213",
      "r214",
      "r215",
      "r217",
      "r218",
      "r219",
      "r220",
      "r221",
      "r222",
      "r223",
      "r328",
      "r331",
      "r332",
      "r336",
      "r337",
      "r353",
      "r363",
      "r448"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.",
        "label": "Net Income (Loss), Including Portion Attributable to Noncontrolling Interest",
        "terseLabel": "Net loss",
        "totalLabel": "Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total"
       }
      }
     },
     "localname": "ProfitLoss",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentByTypeAxis": {
     "auth_ref": [
      "r33",
      "r201"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of long-lived, physical assets used to produce goods and services and not intended for resale.",
        "label": "Long-Lived Tangible Asset [Axis]",
        "terseLabel": "Long-Lived Tangible Asset"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentByTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentGross": {
     "auth_ref": [
      "r32",
      "r199"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails": {
       "order": 0.0,
       "parentTag": "us-gaap_PropertyPlantAndEquipmentNet",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.",
        "label": "Property, Plant and Equipment, Gross",
        "periodEndLabel": "Property, Plant and Equipment, Gross, Ending Balance",
        "periodStartLabel": "Property, Plant and Equipment, Gross, Beginning Balance",
        "terseLabel": "Total property, plant and equipment, gross",
        "totalLabel": "Property, Plant and Equipment, Gross, Total"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentGross",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Property, Plant and Equipment [Line Items]",
        "terseLabel": "Property Plant And Equipment [Line Items]"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentNet": {
     "auth_ref": [
      "r16",
      "r17",
      "r201",
      "r407",
      "r450",
      "r458"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.",
        "label": "Property, Plant and Equipment, Net",
        "periodEndLabel": "Property, Plant and Equipment, Net, Ending Balance",
        "periodStartLabel": "Property, Plant and Equipment, Net, Beginning Balance",
        "terseLabel": "Property, plant and equipment, net",
        "totalLabel": "Total property, plant and equipment, net"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentNet",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentPolicyTextBlock": {
     "auth_ref": [
      "r31",
      "r201",
      "r503",
      "r504"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for long-lived, physical asset used in normal conduct of business and not intended for resale. Includes, but is not limited to, work of art, historical treasure, and similar asset classified as collections.",
        "label": "Property, Plant and Equipment, Policy [Policy Text Block]",
        "terseLabel": "Property, Plant and Equipment"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentTextBlock": {
     "auth_ref": [
      "r16",
      "r201"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation and depletion expense and method used, including composite depreciation, and accumulated deprecation.",
        "label": "Property, Plant and Equipment [Table Text Block]",
        "terseLabel": "Schedule of Property, Plant and Equipment, Net"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentTypeDomain": {
     "auth_ref": [
      "r16",
      "r199"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Listing of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.",
        "label": "Long-Lived Tangible Asset [Domain]",
        "terseLabel": "Long-Lived Tangible Asset"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentUsefulLife": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.",
        "label": "Property, Plant and Equipment, Useful Life",
        "terseLabel": "Property and equipment estimated useful life"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentUsefulLife",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_RelatedPartyDomain": {
     "auth_ref": [
      "r271",
      "r398",
      "r399"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Related parties include affiliates; other entities for which investments are accounted for by the equity method by the entity; trusts for benefit of employees; and principal owners, management, and members of immediate families. It also may include other parties with which the entity may control or can significantly influence the management or operating policies of the other to an extent that one of the transacting parties might be prevented from fully pursuing its own separate interests.",
        "label": "Related Party [Domain]",
        "terseLabel": "Related Party"
       }
      }
     },
     "localname": "RelatedPartyDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RelatedPartyTransactionLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Related Party Transaction [Line Items]",
        "terseLabel": "Related Party Transaction [Line Items]"
       }
      }
     },
     "localname": "RelatedPartyTransactionLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RelatedPartyTransactionsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Related Party Transactions [Abstract]"
       }
      }
     },
     "localname": "RelatedPartyTransactionsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_RelatedPartyTransactionsByRelatedPartyAxis": {
     "auth_ref": [
      "r271",
      "r398",
      "r402",
      "r428",
      "r429",
      "r430",
      "r431",
      "r432",
      "r433",
      "r434",
      "r435",
      "r436",
      "r437",
      "r438",
      "r439"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of related party. Related parties include, but not limited to, affiliates; other entities for which investments are accounted for by the equity method by the entity; trusts for benefit of employees; and principal owners, management, and members of immediate families. It also may include other parties with which the entity may control or can significantly influence the management or operating policies of the other to an extent that one of the transacting parties might be prevented from fully pursuing its own separate interests.",
        "label": "Related Party [Axis]",
        "terseLabel": "Related Party"
       }
      }
     },
     "localname": "RelatedPartyTransactionsByRelatedPartyAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RelatedPartyTransactionsDisclosureTextBlock": {
     "auth_ref": [
      "r396",
      "r397",
      "r399",
      "r403",
      "r404"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.",
        "label": "Related Party Transactions Disclosure [Text Block]",
        "terseLabel": "Related Party Transactions"
       }
      }
     },
     "localname": "RelatedPartyTransactionsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactions"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ResearchAndDevelopmentExpense": {
     "auth_ref": [
      "r313",
      "r421",
      "r516"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_OperatingExpenses",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.",
        "label": "Research and Development Expense",
        "terseLabel": "Research and development",
        "totalLabel": "Research and Development Expense, Total"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpense",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ResearchAndDevelopmentExpenseMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Primary financial statement caption in which the reported facts about research and development expense have been included.",
        "label": "Research and Development Expense [Member]",
        "terseLabel": "Research And Development Expense",
        "verboseLabel": "Research and Development"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ResearchAndDevelopmentExpensePolicy": {
     "auth_ref": [
      "r313"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for costs it has incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process.",
        "label": "Research and Development Expense, Policy [Policy Text Block]",
        "terseLabel": "Research and Development Expenses"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpensePolicy",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_RestrictedCash": {
     "auth_ref": [
      "r88",
      "r440",
      "r454"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 1.0,
       "parentTag": "us-gaap_AssetsCurrent",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.",
        "label": "Restricted Cash",
        "terseLabel": "Restricted cash",
        "totalLabel": "Restricted Cash, Total"
       }
      }
     },
     "localname": "RestrictedCash",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RestrictedCashAndCashEquivalents": {
     "auth_ref": [
      "r15",
      "r83",
      "r88",
      "r440",
      "r454"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.",
        "label": "Restricted Cash and Cash Equivalents",
        "totalLabel": "Restricted Cash and Cash Equivalents, Total"
       }
      }
     },
     "localname": "RestrictedCashAndCashEquivalents",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RestrictedStockMember": {
     "auth_ref": [
      "r123"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock including a provision that prohibits sale or substantive sale of an equity instrument for a specified period of time or until specified performance conditions are met.",
        "label": "Restricted Stock [Member]",
        "terseLabel": "Restricted Stock"
       }
      }
     },
     "localname": "RestrictedStockMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RestrictedStockUnitsRSUMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Share instrument which is convertible to stock or an equivalent amount of cash, after a specified period of time or when specified performance conditions are met.",
        "label": "Restricted Stock Units (RSUs) [Member]",
        "terseLabel": "Restricted Stock Units",
        "verboseLabel": "Unvested restricted stock units"
       }
      }
     },
     "localname": "RestrictedStockUnitsRSUMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RetainedEarningsAccumulatedDeficit": {
     "auth_ref": [
      "r22",
      "r257",
      "r308",
      "r407",
      "r456",
      "r477",
      "r482"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 4.0,
       "parentTag": "us-gaap_StockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cumulative amount of the reporting entity's undistributed earnings or deficit.",
        "label": "Retained Earnings (Accumulated Deficit)",
        "negatedLabel": "Accumulated deficit",
        "periodEndLabel": "Retained Earnings (Accumulated Deficit), Ending Balance",
        "periodStartLabel": "Retained Earnings (Accumulated Deficit), Beginning Balance",
        "terseLabel": "Accumulated deficit",
        "totalLabel": "Retained Earnings (Accumulated Deficit), Total"
       }
      }
     },
     "localname": "RetainedEarningsAccumulatedDeficit",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RetainedEarningsMember": {
     "auth_ref": [
      "r2",
      "r99",
      "r100",
      "r101",
      "r104",
      "r111",
      "r113",
      "r184",
      "r305",
      "r306",
      "r307",
      "r317",
      "r318",
      "r351",
      "r473",
      "r475"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cumulative amount of the reporting entity's undistributed earnings or deficit.",
        "label": "Retained Earnings [Member]",
        "terseLabel": "Accumulated Deficit"
       }
      }
     },
     "localname": "RetainedEarningsMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RevenueFromCollaborativeArrangementExcludingRevenueFromContractWithCustomer": {
     "auth_ref": [
      "r321",
      "r325"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited": {
       "order": 0.0,
       "parentTag": "us-gaap_OperatingIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of revenue from collaborative arrangement. Excludes revenue from contract with customer under Topic 606.",
        "label": "Revenue from Collaborative Arrangement, Excluding Revenue from Contract with Customer",
        "terseLabel": "Collaboration revenue"
       }
      }
     },
     "localname": "RevenueFromCollaborativeArrangementExcludingRevenueFromContractWithCustomer",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RevenueRecognitionPolicyTextBlock": {
     "auth_ref": [
      "r90",
      "r91"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for revenue. Includes revenue from contract with customer and from other sources.",
        "label": "Revenue [Policy Text Block]",
        "terseLabel": "Revenue Recognition"
       }
      }
     },
     "localname": "RevenueRecognitionPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_Revenues": {
     "auth_ref": [
      "r64",
      "r94",
      "r140",
      "r141",
      "r149",
      "r154",
      "r155",
      "r159",
      "r160",
      "r162",
      "r177",
      "r213",
      "r214",
      "r215",
      "r217",
      "r218",
      "r219",
      "r220",
      "r221",
      "r222",
      "r223",
      "r363",
      "r448"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).",
        "label": "Revenues",
        "totalLabel": "Revenues, Total"
       }
      }
     },
     "localname": "Revenues",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability": {
     "auth_ref": [
      "r390",
      "r394"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of increase in right-of-use asset obtained in exchange for operating lease liability.",
        "label": "Right-of-Use Asset Obtained in Exchange for Operating Lease Liability",
        "terseLabel": "Increase in right-of-use asset obtained in exchange for operating lease liability",
        "verboseLabel": "Right-of-use assets recognized in exchange for lease obligations"
       }
      }
     },
     "localname": "RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_SaleOfStockNameOfTransactionDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sale of the entity's stock, including, but not limited to, initial public offering (IPO) and private placement.",
        "label": "Sale of Stock [Domain]",
        "terseLabel": "Sale of Stock"
       }
      }
     },
     "localname": "SaleOfStockNameOfTransactionDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of the components of accrued liabilities.",
        "label": "Schedule of Accrued Liabilities [Table Text Block]",
        "terseLabel": "Schedule of Accrued Liabilities"
       }
      }
     },
     "localname": "ScheduleOfAccruedLiabilitiesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable": {
     "auth_ref": [
      "r123"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Schedule for securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) in the future that were not included in the computation of diluted EPS because to do so would increase EPS amounts or decrease loss per share amounts for the period presented, by Antidilutive Securities.",
        "label": "Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table]",
        "terseLabel": "Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table]"
       }
      }
     },
     "localname": "ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfPotentiallyDilutiveSecuritiesNotIncludedInDilutedPerShareCalculationsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock": {
     "auth_ref": [
      "r123"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) in the future that were not included in the computation of diluted EPS because to do so would increase EPS amounts or decrease loss per share amounts for the period presented, by antidilutive securities.",
        "label": "Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]",
        "terseLabel": "Summary of Potentially Dilutive Securities Not Included in the Diluted Per Share Calculations"
       }
      }
     },
     "localname": "ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable": {
     "auth_ref": [
      "r326"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about collaborative arrangement and arrangement other than collaborative applicable to revenue-generating activity or operations.",
        "label": "Collaborative Arrangement and Arrangement Other than Collaborative [Table]",
        "terseLabel": "Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table]"
       }
      }
     },
     "localname": "ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock": {
     "auth_ref": [
      "r122"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations.",
        "label": "Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]",
        "terseLabel": "Schedule of Computation of Basic and Diluted Net Loss Per Share"
       }
      }
     },
     "localname": "ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureNetLossPerShareAttributableToCommonStockholdersTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable": {
     "auth_ref": [
      "r277",
      "r296",
      "r309"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about amount recognized for award under share-based payment arrangement. Includes, but is not limited to, amount expensed in statement of income or comprehensive income, amount capitalized in statement of financial position, and corresponding reporting line item in financial statements.",
        "label": "Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table]",
        "terseLabel": "Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]"
       }
      }
     },
     "localname": "ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock": {
     "auth_ref": [
      "r277",
      "r296",
      "r309"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement.",
        "label": "Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]",
        "terseLabel": "Summary of Stock-Based Compensation Expense"
       }
      }
     },
     "localname": "ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfPropertyPlantAndEquipmentTable": {
     "auth_ref": [
      "r33",
      "r201"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation and depletion expense and method used, including composite depreciation, and accumulated deprecation.",
        "label": "Property, Plant and Equipment [Table]",
        "terseLabel": "Schedule Of Property Plant And Equipment [Table]"
       }
      }
     },
     "localname": "ScheduleOfPropertyPlantAndEquipmentTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilitiesScheduleOfPropertyPlantAndEquipmentNetDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable": {
     "auth_ref": [
      "r400",
      "r402"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Schedule of quantitative and qualitative information pertaining to related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.",
        "label": "Schedule of Related Party Transactions, by Related Party [Table]",
        "terseLabel": "Schedule Of Related Party Transactions By Related Party [Table]"
       }
      }
     },
     "localname": "ScheduleOfRelatedPartyTransactionsByRelatedPartyTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable": {
     "auth_ref": [
      "r278",
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about share-based payment arrangement.",
        "label": "Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]",
        "terseLabel": "Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]"
       }
      }
     },
     "localname": "ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock": {
     "auth_ref": [
      "r283"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year.",
        "label": "Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]",
        "terseLabel": "Summary of Restricted Stock Unit Activity"
       }
      }
     },
     "localname": "ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock": {
     "auth_ref": [
      "r283"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of the number and weighted-average exercise prices (or conversion ratios) for stock appreciation rights awards that were outstanding at the beginning and end of the year, and the number of stock appreciation rights awards that were granted, exercised or converted, forfeited, and expired during the year.",
        "label": "Share-based Payment Arrangement, Stock Appreciation Right, Activity [Table Text Block]",
        "terseLabel": "Summary of Company's stock awards granted"
       }
      }
     },
     "localname": "ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock": {
     "auth_ref": [
      "r283",
      "r290",
      "r292"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value.",
        "label": "Share-based Payment Arrangement, Option, Activity [Table Text Block]",
        "terseLabel": "Summary of Stock Option"
       }
      }
     },
     "localname": "ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock": {
     "auth_ref": [
      "r294"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions.",
        "label": "Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]",
        "terseLabel": "Summary of Fair Value of Employee Stock Options Estimated Weighted-average Assumptions"
       }
      }
     },
     "localname": "ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfStockByClassTable": {
     "auth_ref": [
      "r42",
      "r92",
      "r128",
      "r129",
      "r231",
      "r232",
      "r233",
      "r234",
      "r235",
      "r236",
      "r237",
      "r239",
      "r243",
      "r248",
      "r251",
      "r252",
      "r253",
      "r254",
      "r255",
      "r256",
      "r257"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Schedule detailing information related to equity by class of stock. Class of stock includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. It also includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity.",
        "label": "Schedule of Stock by Class [Table]",
        "terseLabel": "Schedule Of Stock By Class [Table]"
       }
      }
     },
     "localname": "ScheduleOfStockByClassTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SegmentReportingPolicyPolicyTextBlock": {
     "auth_ref": [
      "r143",
      "r144",
      "r145",
      "r146",
      "r147",
      "r148",
      "r160"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for segment reporting.",
        "label": "Segment Reporting, Policy [Policy Text Block]",
        "terseLabel": "Segments"
       }
      }
     },
     "localname": "SegmentReportingPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ShareBasedCompensation": {
     "auth_ref": [
      "r80"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of noncash expense for share-based payment arrangement.",
        "label": "Share-based Payment Arrangement, Noncash Expense",
        "terseLabel": "Stock-based compensation expense",
        "totalLabel": "Share-based Payment Arrangement, Noncash Expense, Total"
       }
      }
     },
     "localname": "ShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1": {
     "auth_ref": [
      "r279"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period",
        "terseLabel": "Vesting period"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Discount rate from fair value on offering date that participants pay for shares.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date",
        "terseLabel": "Discount rate"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPriceOfferingDate",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod": {
     "auth_ref": [
      "r289"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period",
        "terseLabel": "Granted of common stock"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue": {
     "auth_ref": [
      "r289"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value",
        "terseLabel": "Grant date fair value per share"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award [Line Items]",
        "terseLabel": "Share Based Compensation Arrangement By Share Based Payment Award Line Items"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber": {
     "auth_ref": [
      "r286"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number",
        "terseLabel": "Outstanding Options, Shares, Exercisable"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice": {
     "auth_ref": [
      "r286"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price",
        "terseLabel": "Outstanding Options, Weighted-Average Exercise Price, Exercisable"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod": {
     "auth_ref": [
      "r288"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period",
        "negatedLabel": "Outstanding Options, Shares, Cancelled"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Gross number of share options (or share units) granted during the period.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross",
        "terseLabel": "Number of Shares, Granted"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue": {
     "auth_ref": [
      "r291"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value",
        "terseLabel": "Weighted-Average Grant Date Fair Value"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber": {
     "auth_ref": [
      "r285",
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of options outstanding, including both vested and non-vested options.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number",
        "periodEndLabel": "Outstanding Options, Shares, Ending balance",
        "periodStartLabel": "Outstanding Options, Shares, Beginning balance"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice": {
     "auth_ref": [
      "r284"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price",
        "periodEndLabel": "Outstanding Options, Weighted-Average Exercise Price, Ending balance",
        "periodStartLabel": "Outstanding Options, Weighted-Average Exercise Price, Beginning balance"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Outstanding Stock Maximum",
        "terseLabel": "Outstanding stock including non-voting common stock, percent"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of shares issued under share-based payment arrangement.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period",
        "terseLabel": "Issued of common stock"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain": {
     "auth_ref": [
      "r276",
      "r281"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Award under share-based payment arrangement.",
        "label": "Award Type [Domain]",
        "terseLabel": "Award Type"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockbasedCompensationSummaryOfCompanysStockAwardsGrantedDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average price at which option holders acquired shares when converting their stock options into shares.",
        "label": "Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price",
        "terseLabel": "Outstanding Options, Weighted-Average Exercise Price, Exercised"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.",
        "label": "Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price",
        "terseLabel": "Outstanding Options, Weighted-Average Exercise Price, Canceled"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.",
        "label": "Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price",
        "terseLabel": "Outstanding Options, Weighted-Average Exercise Price, Granted"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationAwardTrancheOneMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "First portion of award under share-based payment arrangement differentiated by vesting feature, including, but not limited to, performance measure or service period.",
        "label": "Share-based Payment Arrangement, Tranche One [Member]",
        "terseLabel": "Share-based Compensation Award, Tranche One"
       }
      }
     },
     "localname": "ShareBasedCompensationAwardTrancheOneMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy": {
     "auth_ref": [
      "r278",
      "r282"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for award under share-based payment arrangement. Includes, but is not limited to, methodology and assumption used in measuring cost.",
        "label": "Share-based Payment Arrangement [Policy Text Block]",
        "terseLabel": "Stock-Based Compensation"
       }
      }
     },
     "localname": "ShareBasedCompensationOptionAndIncentivePlansPolicy",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod": {
     "auth_ref": [
      "r280"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period",
        "terseLabel": "Term of options"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term",
        "terseLabel": "Outstanding Options, Weighted Average Remaining Contractual Term (Years), Exercisable"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2": {
     "auth_ref": [
      "r293"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term",
        "terseLabel": "Outstanding Options, Weighted Average Remaining Contractual Term (Years)"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Purchase price of common stock expressed as a percentage of its fair value.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent",
        "terseLabel": "Percentage of exercise price of stock option on estimated fair value of shares"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_SharesIssuedPricePerShare": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Per share or per unit amount of equity securities issued.",
        "label": "Shares Issued, Price Per Share",
        "terseLabel": "Common stock, price per share"
       }
      }
     },
     "localname": "SharesIssuedPricePerShare",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_SharesOutstanding": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of shares issued which are neither cancelled nor held in the treasury.",
        "label": "Shares, Outstanding",
        "periodEndLabel": "Balance, shares",
        "periodStartLabel": "Balance, shares"
       }
      }
     },
     "localname": "SharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_SignificantAccountingPoliciesTextBlock": {
     "auth_ref": [
      "r89",
      "r98"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for all significant accounting policies of the reporting entity.",
        "label": "Significant Accounting Policies [Text Block]",
        "terseLabel": "Summary of Significant Accounting Policies"
       }
      }
     },
     "localname": "SignificantAccountingPoliciesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_StatementClassOfStockAxis": {
     "auth_ref": [
      "r18",
      "r19",
      "r20",
      "r92",
      "r94",
      "r116",
      "r117",
      "r118",
      "r120",
      "r122",
      "r128",
      "r129",
      "r130",
      "r177",
      "r213",
      "r217",
      "r218",
      "r219",
      "r222",
      "r223",
      "r234",
      "r235",
      "r239",
      "r243",
      "r250",
      "r363",
      "r522"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by the different classes of stock of the entity.",
        "label": "Class of Stock [Axis]",
        "terseLabel": "Class of Stock"
       }
      }
     },
     "localname": "StatementClassOfStockAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DocumentDocumentAndEntityInformation",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementEquityComponentsAxis": {
     "auth_ref": [
      "r2",
      "r45",
      "r61",
      "r62",
      "r63",
      "r99",
      "r100",
      "r101",
      "r104",
      "r111",
      "r113",
      "r127",
      "r184",
      "r250",
      "r257",
      "r305",
      "r306",
      "r307",
      "r317",
      "r318",
      "r351",
      "r374",
      "r375",
      "r376",
      "r377",
      "r378",
      "r379",
      "r473",
      "r474",
      "r475",
      "r529"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by component of equity.",
        "label": "Equity Components [Axis]",
        "terseLabel": "Equity Components"
       }
      }
     },
     "localname": "StatementEquityComponentsAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Statement [Line Items]",
        "terseLabel": "Statement [Line Items]"
       }
      }
     },
     "localname": "StatementLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfCashFlowsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement of Cash Flows [Abstract]"
       }
      }
     },
     "localname": "StatementOfCashFlowsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfFinancialPositionAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement of Financial Position [Abstract]"
       }
      }
     },
     "localname": "StatementOfFinancialPositionAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement of Comprehensive Income [Abstract]"
       }
      }
     },
     "localname": "StatementOfIncomeAndComprehensiveIncomeAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfStockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement of Stockholders' Equity [Abstract]"
       }
      }
     },
     "localname": "StatementOfStockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementTable": {
     "auth_ref": [
      "r99",
      "r100",
      "r101",
      "r127",
      "r422"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Schedule reflecting a Statement of Income, Statement of Cash Flows, Statement of Financial Position, Statement of Shareholders' Equity and Other Comprehensive Income, or other statement as needed.",
        "label": "Statement [Table]",
        "terseLabel": "Statement [Table]"
       }
      }
     },
     "localname": "StatementTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities": {
     "auth_ref": [
      "r44",
      "r227",
      "r250",
      "r251",
      "r257"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of shares issued during the period as a result of the conversion of convertible securities.",
        "label": "Stock Issued During Period, Shares, Conversion of Convertible Securities",
        "terseLabel": "Conversion of non-voting common stock into voting common stock, Shares"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans": {
     "auth_ref": [
      "r19",
      "r20",
      "r250",
      "r257"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of shares issued during the period as a result of an employee stock purchase plan.",
        "label": "Stock Issued During Period, Shares, Employee Stock Purchase Plans",
        "terseLabel": "Purchases under employee stock purchase plan, shares"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesNewIssues": {
     "auth_ref": [
      "r19",
      "r20",
      "r250",
      "r257"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of new stock issued during the period.",
        "label": "Stock Issued During Period, Shares, New Issues",
        "terseLabel": "Issuance of common stock, shares",
        "verboseLabel": "Issuance of common stock in connection with public offering, net of offering costs, Shares"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesNewIssues",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross": {
     "auth_ref": [
      "r250",
      "r257"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.",
        "label": "Stock Issued During Period, Shares, Restricted Stock Award, Gross",
        "terseLabel": "Issuance of common stock upon restricted stock unit settlement, shares"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesRestrictedStockAwardGross",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures": {
     "auth_ref": [
      "r19",
      "r20",
      "r250",
      "r257"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of shares issued during the period related to Restricted Stock Awards, net of any shares forfeited.",
        "label": "Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures",
        "terseLabel": "Vesting of restricted stock, shares",
        "totalLabel": "Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures, Total"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised": {
     "auth_ref": [
      "r19",
      "r20",
      "r250",
      "r257",
      "r287"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of share options (or share units) exercised during the current period.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period",
        "negatedLabel": "Outstanding Options, Shares, Exercised",
        "terseLabel": "Exercise of stock options, Shares"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesStockOptionsExercised",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationSummaryOfStockOptionDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities": {
     "auth_ref": [
      "r45",
      "r250",
      "r257"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The gross value of stock issued during the period upon the conversion of convertible securities.",
        "label": "Stock Issued During Period, Value, Conversion of Convertible Securities",
        "terseLabel": "Conversion of non-voting common stock into voting common stock"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueConversionOfConvertibleSecurities",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan": {
     "auth_ref": [
      "r19",
      "r20",
      "r250",
      "r257"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Aggregate change in value for stock issued during the period as a result of employee stock purchase plan.",
        "label": "Stock Issued During Period, Value, Employee Stock Purchase Plan",
        "terseLabel": "Purchases under employee stock purchase plan"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueEmployeeStockPurchasePlan",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueNewIssues": {
     "auth_ref": [
      "r19",
      "r20",
      "r250",
      "r257"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.",
        "label": "Stock Issued During Period, Value, New Issues",
        "terseLabel": "Stock issued during period value",
        "verboseLabel": "Issuance of common stock in connection with public offering, net of offering costs"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueNewIssues",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureSanofiAgreementAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures": {
     "auth_ref": [
      "r250",
      "r257"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Value of stock related to Restricted Stock Awards issued during the period, net of the stock value of such awards forfeited.",
        "label": "Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures",
        "terseLabel": "Vesting of restricted stock",
        "totalLabel": "Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures, Total"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised": {
     "auth_ref": [
      "r45",
      "r250",
      "r257"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Value of stock issued as a result of the exercise of stock options.",
        "label": "Stock Issued During Period, Value, Stock Options Exercised",
        "terseLabel": "Exercise of stock options"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueStockOptionsExercised",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquity": {
     "auth_ref": [
      "r20",
      "r24",
      "r25",
      "r94",
      "r164",
      "r177",
      "r363",
      "r407"
     ],
     "calculation": {
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited": {
       "order": 2.0,
       "parentTag": "us-gaap_LiabilitiesAndStockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.",
        "label": "Stockholders' Equity Attributable to Parent",
        "periodEndLabel": "Balance",
        "periodStartLabel": "Balance",
        "totalLabel": "Total stockholders\u2019 equity"
       }
      }
     },
     "localname": "StockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited",
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Stockholders' Equity Attributable to Parent [Abstract]",
        "terseLabel": "Stockholders' equity:"
       }
      }
     },
     "localname": "StockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockholdersEquityNoteAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Stockholders' Equity Note [Abstract]"
       }
      }
     },
     "localname": "StockholdersEquityNoteAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockholdersEquityNoteDisclosureTextBlock": {
     "auth_ref": [
      "r93",
      "r235",
      "r238",
      "r239",
      "r240",
      "r241",
      "r242",
      "r243",
      "r244",
      "r245",
      "r246",
      "r247",
      "r249",
      "r257",
      "r259"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.",
        "label": "Stockholders' Equity Note Disclosure [Text Block]",
        "terseLabel": "Stockholders' Equity"
       }
      }
     },
     "localname": "StockholdersEquityNoteDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquity1"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SubsequentEventLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.",
        "label": "Subsequent Event [Line Items]",
        "terseLabel": "Subsequent Event [Line Items]"
       }
      }
     },
     "localname": "SubsequentEventLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubsequentEventMember": {
     "auth_ref": [
      "r380",
      "r409"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Identifies event that occurred after the balance sheet date but before financial statements are issued or available to be issued.",
        "label": "Subsequent Event [Member]",
        "terseLabel": "Subsequent Event"
       }
      }
     },
     "localname": "SubsequentEventMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SubsequentEventTable": {
     "auth_ref": [
      "r380",
      "r409"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Discloses pertinent information about one or more significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued.",
        "label": "Subsequent Event [Table]",
        "terseLabel": "Subsequent Event [Table]"
       }
      }
     },
     "localname": "SubsequentEventTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubsequentEventTypeAxis": {
     "auth_ref": [
      "r380",
      "r409"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by event that occurred after the balance sheet date but before financial statements are issued or available to be issued.",
        "label": "Subsequent Event Type [Axis]",
        "terseLabel": "Subsequent Event Type"
       }
      }
     },
     "localname": "SubsequentEventTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubsequentEventTypeDomain": {
     "auth_ref": [
      "r380",
      "r409"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Event that occurred after the balance sheet date but before financial statements are issued or available to be issued.",
        "label": "Subsequent Event Type [Domain]",
        "terseLabel": "Subsequent Event Type"
       }
      }
     },
     "localname": "SubsequentEventTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SubsequentEventsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Subsequent Events [Abstract]"
       }
      }
     },
     "localname": "SubsequentEventsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubsequentEventsTextBlock": {
     "auth_ref": [
      "r408",
      "r410"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.",
        "label": "Subsequent Events [Text Block]",
        "terseLabel": "Subsequent Events"
       }
      }
     },
     "localname": "SubsequentEventsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSubsequentEvents"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Different names of stock transactions and the different attributes of each transaction.",
        "label": "Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table]",
        "terseLabel": "Subsidiary Or Equity Method Investee Sale Of Stock By Subsidiary Or Equity Investee [Table]"
       }
      }
     },
     "localname": "SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubsidiarySaleOfStockAxis": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of sale of the entity's stock.",
        "label": "Sale of Stock [Axis]",
        "terseLabel": "Sale of Stock"
       }
      }
     },
     "localname": "SubsidiarySaleOfStockAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureStockholdersEquityPrefundedWarrantsAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails",
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubsidiarySaleOfStockLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Subsidiary, Sale of Stock [Line Items]",
        "terseLabel": "Subsidiary Sale Of Stock [Line Items]"
       }
      }
     },
     "localname": "SubsidiarySaleOfStockLineItems",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureOrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SupplementalBalanceSheetDisclosuresTextBlock": {
     "auth_ref": [
      "r50"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for supplemental balance sheet disclosures, including descriptions and amounts for assets, liabilities, and equity.",
        "label": "Supplemental Balance Sheet Disclosures [Text Block]",
        "terseLabel": "Accrued Liabilities"
       }
      }
     },
     "localname": "SupplementalBalanceSheetDisclosuresTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/DisclosureAccruedLiabilities1"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_TypeOfAdoptionMember": {
     "auth_ref": [
      "r0",
      "r1",
      "r2",
      "r3",
      "r4",
      "r103",
      "r104",
      "r105",
      "r106",
      "r115",
      "r165",
      "r166",
      "r181",
      "r182",
      "r183",
      "r184",
      "r186",
      "r187",
      "r212",
      "r301",
      "r302",
      "r303",
      "r304",
      "r305",
      "r306",
      "r307",
      "r308",
      "r315",
      "r316",
      "r317",
      "r318",
      "r343",
      "r344",
      "r345",
      "r346",
      "r347",
      "r348",
      "r349",
      "r350",
      "r351",
      "r352",
      "r353",
      "r364",
      "r365",
      "r367",
      "r368",
      "r369",
      "r370",
      "r371",
      "r372",
      "r395",
      "r424",
      "r425",
      "r426",
      "r471",
      "r472",
      "r473",
      "r474",
      "r475",
      "r476",
      "r477",
      "r478",
      "r479",
      "r480",
      "r481",
      "r482",
      "r525",
      "r526",
      "r527",
      "r528",
      "r529"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amendment to accounting standards.",
        "label": "Accounting Standards Update [Domain]",
        "terseLabel": "Accounting Standards Update"
       }
      }
     },
     "localname": "TypeOfAdoptionMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_TypeOfArrangementAxis": {
     "auth_ref": [
      "r326"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by collaborative arrangement and arrangement other than collaborative applicable to revenue-generating activity or operations.",
        "label": "Collaborative Arrangement and Arrangement Other than Collaborative [Axis]",
        "terseLabel": "Collaborative Arrangement and Arrangement Other than Collaborative"
       }
      }
     },
     "localname": "TypeOfArrangementAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureLicenseAgreementsAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_USGovernmentAgenciesDebtSecuritiesMember": {
     "auth_ref": [
      "r95",
      "r264",
      "r449"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Debentures, notes, and other debt securities issued by US government agencies, for example, but not limited to, Government National Mortgage Association (GNMA or Ginnie Mae). Excludes US treasury securities and debt issued by government-sponsored Enterprises (GSEs), for example, but is not limited to, Federal Home Loan Mortgage Corporation (FHLMC or Freddie Mac), Federal National Mortgage Association (FNMA or Fannie Mae), and the Federal Home Loan Bank (FHLB).",
        "label": "US Government Agencies Debt Securities [Member]",
        "terseLabel": "U.S. Government Agency Securities"
       }
      }
     },
     "localname": "USGovernmentAgenciesDebtSecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_USTreasurySecuritiesMember": {
     "auth_ref": [
      "r95",
      "r264",
      "r272",
      "r449"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "This category includes information about debt securities issued by the United States Department of the Treasury and backed by the United States government. Such securities primarily consist of treasury bills (short-term maturities - one year or less), treasury notes (intermediate term maturities - two to ten years), and treasury bonds (long-term maturities - ten to thirty years).",
        "label": "US Treasury Securities [Member]",
        "terseLabel": "U.S. Treasury Securities"
       }
      }
     },
     "localname": "USTreasurySecuritiesMember",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureFairValueMeasurementSummaryOfInvestmentsMeasuredAndRecognizedAtFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_UseOfEstimates": {
     "auth_ref": [
      "r131",
      "r132",
      "r134",
      "r135",
      "r136",
      "r137",
      "r138"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for the use of estimates in the preparation of financial statements in conformity with generally accepted accounting principles.",
        "label": "Use of Estimates, Policy [Policy Text Block]",
        "terseLabel": "Use of Estimates"
       }
      }
     },
     "localname": "UseOfEstimates",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_VariableLeaseCost": {
     "auth_ref": [
      "r388",
      "r394"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.",
        "label": "Variable Lease, Cost",
        "terseLabel": "Variable lease cost"
       }
      }
     },
     "localname": "VariableLeaseCost",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesScheduleOfROUAssetsAndRelatedLeaseLiabilitiesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_VestingAxis": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by vesting schedule of award under share-based payment arrangement.",
        "label": "Vesting [Axis]",
        "terseLabel": "Vesting"
       }
      }
     },
     "localname": "VestingAxis",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_VestingDomain": {
     "auth_ref": [
      "r299"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Vesting schedule of award under share-based payment arrangement.",
        "label": "Vesting [Domain]",
        "terseLabel": "Vesting"
       }
      }
     },
     "localname": "VestingDomain",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).",
        "label": "Weighted Average Number of Shares Outstanding, Basic and Diluted",
        "terseLabel": "Weighted-average common shares outstanding, basic and diluted"
       }
      }
     },
     "localname": "WeightedAverageNumberOfShareOutstandingBasicAndDiluted",
     "nsuri": "http://fasb.org/us-gaap/2021-01-31",
     "presentation": [
      "http://igmbio.com/20220630/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsUnaudited"
     ],
     "xbrltype": "sharesItemType"
    }
   },
   "unitCount": 7
  }
 },
 "std_ref": {
  "r0": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "105",
   "URI": "http://asc.fasb.org/extlink&oid=124434974&loc=SL124442142-165695"
  },
  "r1": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "105",
   "URI": "http://asc.fasb.org/extlink&oid=124434974&loc=SL124442142-165695"
  },
  "r10": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765"
  },
  "r100": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "24",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124436220&loc=d3e21930-107793"
  },
  "r101": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124436220&loc=d3e21711-107793"
  },
  "r102": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22499-107794"
  },
  "r103": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(2)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22499-107794"
  },
  "r104": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(3)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22499-107794"
  },
  "r105": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(4)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22499-107794"
  },
  "r106": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22499-107794"
  },
  "r107": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22694-107794"
  },
  "r108": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22694-107794"
  },
  "r109": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22583-107794"
  },
  "r11": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=124098289&loc=d3e6801-107765"
  },
  "r110": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22595-107794"
  },
  "r111": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22644-107794"
  },
  "r112": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22658-107794"
  },
  "r113": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124431687&loc=d3e22663-107794"
  },
  "r114": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=122038215&loc=d3e31010-122693"
  },
  "r115": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 11.M.Q2)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=122038215&loc=d3e31137-122693"
  },
  "r116": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=125511455&loc=d3e1252-109256"
  },
  "r117": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=125511455&loc=d3e1278-109256"
  },
  "r118": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "55",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=125511455&loc=d3e2626-109256"
  },
  "r119": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "60B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=125511455&loc=SL5780133-109256"
  },
  "r12": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=124098289&loc=d3e6911-107765"
  },
  "r120": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "60B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=125511455&loc=SL5780133-109256"
  },
  "r121": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=125511455&loc=d3e1337-109256"
  },
  "r122": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=124432515&loc=d3e3550-109257"
  },
  "r123": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=124432515&loc=d3e3550-109257"
  },
  "r124": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=124432515&loc=d3e3630-109257"
  },
  "r125": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=109243012&loc=SL65017193-207537"
  },
  "r126": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "260",
   "URI": "http://asc.fasb.org/topic&trid=2144383"
  },
  "r127": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=125520817&loc=d3e70191-108054"
  },
  "r128": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=125520817&loc=d3e70229-108054"
  },
  "r129": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055"
  },
  "r13": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=124098289&loc=d3e6935-107765"
  },
  "r130": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055"
  },
  "r131": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e5967-108592"
  },
  "r132": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e5967-108592"
  },
  "r133": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e5967-108592"
  },
  "r134": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e6161-108592"
  },
  "r135": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e6191-108592"
  },
  "r136": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e6061-108592"
  },
  "r137": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e6132-108592"
  },
  "r138": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e6143-108592"
  },
  "r139": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "18",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8672-108599"
  },
  "r14": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=124098289&loc=d3e7018-107765"
  },
  "r140": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599"
  },
  "r141": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599"
  },
  "r142": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599"
  },
  "r143": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8864-108599"
  },
  "r144": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8864-108599"
  },
  "r145": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8864-108599"
  },
  "r146": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8864-108599"
  },
  "r147": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8864-108599"
  },
  "r148": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8864-108599"
  },
  "r149": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599"
  },
  "r15": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(1))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r150": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599"
  },
  "r151": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599"
  },
  "r152": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599"
  },
  "r153": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "31",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8924-108599"
  },
  "r154": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599"
  },
  "r155": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599"
  },
  "r156": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599"
  },
  "r157": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599"
  },
  "r158": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599"
  },
  "r159": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "40",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e9031-108599"
  },
  "r16": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(13))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r160": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "41",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e9038-108599"
  },
  "r161": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "41",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e9038-108599"
  },
  "r162": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "42",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599"
  },
  "r163": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=124259787&loc=d3e4647-111522"
  },
  "r164": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 4.E)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=122038336&loc=d3e74512-122707"
  },
  "r165": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=124402435&loc=SL124402458-218513"
  },
  "r166": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=124402435&loc=SL124402458-218513"
  },
  "r167": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(d)(1)",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=124402435&loc=SL124402458-218513"
  },
  "r168": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562"
  },
  "r169": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=124260329&loc=d3e26853-111562"
  },
  "r17": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(14))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r170": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=124260329&loc=d3e26626-111562"
  },
  "r171": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563"
  },
  "r172": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(aa)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563"
  },
  "r173": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563"
  },
  "r174": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563"
  },
  "r175": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=123581744&loc=d3e27290-111563"
  },
  "r176": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(2)",
   "Topic": "323",
   "URI": "http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571"
  },
  "r177": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "323",
   "URI": "http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571"
  },
  "r178": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL120254519-210437"
  },
  "r179": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL120320025-210437"
  },
  "r18": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(27))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r180": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL120320025-210437"
  },
  "r181": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL121648383-210437"
  },
  "r182": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL121648383-210437"
  },
  "r183": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL121648383-210437"
  },
  "r184": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL121648383-210437"
  },
  "r185": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(1)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL121648383-210437"
  },
  "r186": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(3)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL121648383-210437"
  },
  "r187": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(4)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=122640432&loc=SL121648383-210437"
  },
  "r188": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454"
  },
  "r189": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(1)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=124269663&loc=SL82922888-210455"
  },
  "r19": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(28))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r190": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456"
  },
  "r191": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275"
  },
  "r192": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(d)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275"
  },
  "r193": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275"
  },
  "r194": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)(1)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275"
  },
  "r195": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(d)",
   "Topic": "350",
   "URI": "http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275"
  },
  "r196": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "05",
   "SubTopic": "10",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=109226317&loc=d3e202-110218"
  },
  "r197": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=123351718&loc=d3e2611-110228"
  },
  "r198": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229"
  },
  "r199": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229"
  },
  "r2": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "105",
   "URI": "http://asc.fasb.org/extlink&oid=124434974&loc=SL124442142-165695"
  },
  "r20": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(29))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r200": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229"
  },
  "r201": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229"
  },
  "r202": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230"
  },
  "r203": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 5.CC)",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=27011434&loc=d3e125687-122742"
  },
  "r204": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869"
  },
  "r205": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "440",
   "URI": "http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308"
  },
  "r206": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "440",
   "URI": "http://asc.fasb.org/extlink&oid=123406679&loc=d3e25336-109308"
  },
  "r207": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "440",
   "URI": "http://asc.fasb.org/topic&trid=2144648"
  },
  "r208": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349"
  },
  "r209": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "450",
   "URI": "http://asc.fasb.org/topic&trid=2127136"
  },
  "r21": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30)(a)(1))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r210": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "25",
   "SubTopic": "10",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=28183603&loc=d3e692-112598"
  },
  "r211": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=99376301&loc=SL5988623-112600"
  },
  "r212": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S65",
   "SubTopic": "10",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359872&loc=SL124427846-239511"
  },
  "r213": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-01(a)(4)(i))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756"
  },
  "r214": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-01(a)(4)(ii))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756"
  },
  "r215": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-01(a)(4)(iii)(A))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756"
  },
  "r216": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-01(a)(4)(iii))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756"
  },
  "r217": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-01(a)(4)(iv))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756"
  },
  "r218": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-01(a)(5))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442526-122756"
  },
  "r219": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-02(a)(4)(i))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756"
  },
  "r22": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30)(a)(3))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r220": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-02(a)(4)(iii)(A))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756"
  },
  "r221": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-02(a)(4)(iii)(B))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756"
  },
  "r222": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-02(a)(4)(iv))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756"
  },
  "r223": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.13-02(a)(5))",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=124359900&loc=SL124442552-122756"
  },
  "r224": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611"
  },
  "r225": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(e)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611"
  },
  "r226": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611"
  },
  "r227": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1E",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=123466505&loc=SL123495348-112611"
  },
  "r228": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "69B",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612"
  },
  "r229": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "69C",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612"
  },
  "r23": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30)(a)(4))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r230": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "63",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "480",
   "URI": "http://asc.fasb.org/extlink&oid=117411753&loc=d3e23176-110880"
  },
  "r231": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(CFRR 211.02)",
   "Topic": "480",
   "URI": "http://asc.fasb.org/extlink&oid=122040564&loc=d3e177068-122764"
  },
  "r232": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=65888546&loc=d3e21300-112643"
  },
  "r233": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=d3e21553-112644"
  },
  "r234": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644"
  },
  "r235": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644"
  },
  "r236": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644"
  },
  "r237": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644"
  },
  "r238": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(g)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644"
  },
  "r239": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644"
  },
  "r24": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r240": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(i)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644"
  },
  "r241": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644"
  },
  "r242": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644"
  },
  "r243": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644"
  },
  "r244": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644"
  },
  "r245": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496180-112644"
  },
  "r246": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "18",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644"
  },
  "r247": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "18",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644"
  },
  "r248": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "18",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644"
  },
  "r249": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "18",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644"
  },
  "r25": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(31))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r250": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644"
  },
  "r251": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644"
  },
  "r252": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=d3e21484-112644"
  },
  "r253": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=d3e21488-112644"
  },
  "r254": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=d3e21506-112644"
  },
  "r255": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=d3e21521-112644"
  },
  "r256": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=123467817&loc=d3e21538-112644"
  },
  "r257": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.3-04)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770"
  },
  "r258": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "50",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=6784392&loc=d3e188667-122775"
  },
  "r259": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "505",
   "URI": "http://asc.fasb.org/topic&trid=2208762"
  },
  "r26": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(32))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r260": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=123351226&loc=SL49130545-203045"
  },
  "r261": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "91",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=123410239&loc=SL49130690-203046-203046"
  },
  "r262": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "91",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=123410239&loc=SL49130690-203046-203046"
  },
  "r263": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(i)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r264": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(ii)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r265": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(01)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r266": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r267": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)(A)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r268": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)(B)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r269": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)(C)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r27": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(5))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r270": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(03)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r271": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(n)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920"
  },
  "r272": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921"
  },
  "r273": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "80",
   "Subparagraph": "(d)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947"
  },
  "r274": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "80",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948"
  },
  "r275": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "35",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=123468992&loc=d3e4534-113899"
  },
  "r276": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r277": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r278": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r279": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r28": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(7))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r280": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r281": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a),(g)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r282": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b),(f)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r283": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r284": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r285": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(i)-(ii)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r286": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(iii)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r287": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(iv)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r288": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(iv)(3)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r289": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)(iii)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r29": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(8))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r290": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r291": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r292": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r293": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r294": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r295": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(g)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r296": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r297": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)(1)(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r298": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r299": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r3": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "105",
   "URI": "http://asc.fasb.org/extlink&oid=124434974&loc=SL124442142-165695"
  },
  "r30": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.1)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r300": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=SL79508275-113901"
  },
  "r301": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r302": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r303": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r304": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r305": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r306": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(f)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r307": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r308": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(g)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r309": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 14.F)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809"
  },
  "r31": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.13(a))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r310": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=122142933&loc=d3e11149-113907"
  },
  "r311": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=122142933&loc=d3e11178-113907"
  },
  "r312": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "718",
   "URI": "http://asc.fasb.org/topic&trid=2228938"
  },
  "r313": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "730",
   "URI": "http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373"
  },
  "r314": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "730",
   "URI": "http://asc.fasb.org/extlink&oid=6420387&loc=d3e23199-108380"
  },
  "r315": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=123459177&loc=SL121830611-158277"
  },
  "r316": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=123459177&loc=SL121830611-158277"
  },
  "r317": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)(2)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=123459177&loc=SL121830611-158277"
  },
  "r318": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)(3)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=123459177&loc=SL121830611-158277"
  },
  "r319": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)(3)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=123459177&loc=SL121830611-158277"
  },
  "r32": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.13)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r320": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "31",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "805",
   "URI": "http://asc.fasb.org/extlink&oid=123410050&loc=d3e5419-128473"
  },
  "r321": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "808",
   "URI": "http://asc.fasb.org/extlink&oid=123385629&loc=SL5834089-161433"
  },
  "r322": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "808",
   "URI": "http://asc.fasb.org/extlink&oid=6931272&loc=SL5834143-161434"
  },
  "r323": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "808",
   "URI": "http://asc.fasb.org/extlink&oid=6931272&loc=SL5834143-161434"
  },
  "r324": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "808",
   "URI": "http://asc.fasb.org/extlink&oid=6931272&loc=SL5834143-161434"
  },
  "r325": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "808",
   "URI": "http://asc.fasb.org/extlink&oid=6931272&loc=SL5834143-161434"
  },
  "r326": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "808",
   "URI": "http://asc.fasb.org/extlink&oid=6931272&loc=SL5834143-161434"
  },
  "r327": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "808",
   "URI": "http://asc.fasb.org/topic&trid=5833765"
  },
  "r328": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "19",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=123454820&loc=SL4569616-111683"
  },
  "r329": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988"
  },
  "r33": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.14)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r330": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988"
  },
  "r331": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684"
  },
  "r332": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684"
  },
  "r333": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c),(3)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684"
  },
  "r334": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bb)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=123419778&loc=d3e5710-111685"
  },
  "r335": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=123419778&loc=d3e5710-111685"
  },
  "r336": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4J",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=120409616&loc=SL4591551-111686"
  },
  "r337": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4K",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=120409616&loc=SL4591552-111686"
  },
  "r338": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "810",
   "URI": "http://asc.fasb.org/topic&trid=2197479"
  },
  "r339": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=121483254&loc=SL120254523-199619"
  },
  "r34": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.15)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r340": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123477628&loc=d3e90193-114008"
  },
  "r341": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123477628&loc=d3e90198-114008"
  },
  "r342": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123477628&loc=d3e90205-114008"
  },
  "r343": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(a)(1)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r344": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(a)(2)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r345": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(a)(3)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r346": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(b)(1)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r347": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(b)(2)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r348": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(c)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r349": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(d)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r35": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.17)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r350": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(e)(2)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r351": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(e)(3)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r352": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(e)(4)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r353": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(f)",
   "Topic": "815",
   "URI": "http://asc.fasb.org/extlink&oid=123482062&loc=SL123482106-238011"
  },
  "r354": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258"
  },
  "r355": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258"
  },
  "r356": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bb)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258"
  },
  "r357": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bbb)(1)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258"
  },
  "r358": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bbb)(2)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258"
  },
  "r359": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258"
  },
  "r36": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19(a))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r360": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258"
  },
  "r361": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=d3e19279-110258"
  },
  "r362": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=123874694&loc=SL6742756-110258"
  },
  "r363": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123596393&loc=d3e14064-108612"
  },
  "r364": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL120254526-165497"
  },
  "r365": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL120254526-165497"
  },
  "r366": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL120254526-165497"
  },
  "r367": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL121967933-165497"
  },
  "r368": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL121967933-165497"
  },
  "r369": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL121967933-165497"
  },
  "r37": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19-26)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r370": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(c)(2)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL121967933-165497"
  },
  "r371": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL122642865-165497"
  },
  "r372": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=123597120&loc=SL122642865-165497"
  },
  "r373": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "230",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=123444420&loc=d3e33268-110906"
  },
  "r374": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32136-110900"
  },
  "r375": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r376": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(b)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r377": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(c)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r378": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(d)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r379": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=6450520&loc=d3e32583-110901"
  },
  "r38": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.2)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r380": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=6450520&loc=d3e32618-110901"
  },
  "r381": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123341672&loc=SL120154346-209984"
  },
  "r382": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977"
  },
  "r383": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977"
  },
  "r384": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123391704&loc=SL77918643-209977"
  },
  "r385": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918666-209980"
  },
  "r386": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918673-209980"
  },
  "r387": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980"
  },
  "r388": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980"
  },
  "r389": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(1)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980"
  },
  "r39": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.20)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r390": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(2)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980"
  },
  "r391": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(3)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980"
  },
  "r392": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(4)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980"
  },
  "r393": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123408670&loc=SL77918701-209980"
  },
  "r394": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "53",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971"
  },
  "r395": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "848",
   "URI": "http://asc.fasb.org/extlink&oid=122150657&loc=SL122150809-237846"
  },
  "r396": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864"
  },
  "r397": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864"
  },
  "r398": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864"
  },
  "r399": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864"
  },
  "r4": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "105",
   "URI": "http://asc.fasb.org/extlink&oid=124434974&loc=SL124442142-165695"
  },
  "r40": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.21)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r400": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864"
  },
  "r401": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39599-107864"
  },
  "r402": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864"
  },
  "r403": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39691-107864"
  },
  "r404": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "850",
   "URI": "http://asc.fasb.org/topic&trid=2122745"
  },
  "r405": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "852",
   "URI": "http://asc.fasb.org/extlink&oid=124433192&loc=SL2890621-112765"
  },
  "r406": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "852",
   "URI": "http://asc.fasb.org/extlink&oid=124433192&loc=SL2890621-112765"
  },
  "r407": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "852",
   "URI": "http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766"
  },
  "r408": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "855",
   "URI": "http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662"
  },
  "r409": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "855",
   "URI": "http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662"
  },
  "r41": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.25)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r410": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "855",
   "URI": "http://asc.fasb.org/topic&trid=2122774"
  },
  "r411": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r412": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r413": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r414": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r415": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r416": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r417": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r418": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r419": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r42": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.28,29)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r420": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "910",
   "URI": "http://asc.fasb.org/extlink&oid=123353855&loc=SL119991595-234733"
  },
  "r421": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "25",
   "SubTopic": "730",
   "Topic": "912",
   "URI": "http://asc.fasb.org/extlink&oid=6472174&loc=d3e58812-109433"
  },
  "r422": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 11.L)",
   "Topic": "924",
   "URI": "http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856"
  },
  "r423": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154696&loc=d3e54445-107959"
  },
  "r424": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r425": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r426": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "926",
   "URI": "http://asc.fasb.org/extlink&oid=120154821&loc=SL120154904-197079"
  },
  "r427": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "340",
   "Topic": "928",
   "URI": "http://asc.fasb.org/extlink&oid=6473545&loc=d3e61844-108004"
  },
  "r428": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e61929-109447"
  },
  "r429": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e61929-109447"
  },
  "r43": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.29)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r430": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e62059-109447"
  },
  "r431": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e62059-109447"
  },
  "r432": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e62395-109447"
  },
  "r433": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e62395-109447"
  },
  "r434": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "33",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e62479-109447"
  },
  "r435": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "33",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e62479-109447"
  },
  "r436": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "35A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=SL6807758-109447"
  },
  "r437": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "35A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=SL6807758-109447"
  },
  "r438": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(c)(1)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e61872-109447"
  },
  "r439": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(c)(2)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=123377692&loc=d3e61872-109447"
  },
  "r44": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.29-30)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r440": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(1)(a))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r441": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(11))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r442": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(23))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r443": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(6))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r444": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.15(1),(5))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r445": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.17)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r446": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(22))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r447": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(26))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r448": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "235",
   "Subparagraph": "(SX 210.9-05(b)(2))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884"
  },
  "r449": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "320",
   "Subparagraph": "(b)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=123599081&loc=d3e62557-112803"
  },
  "r45": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.29-31)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r450": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "360",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=124429447&loc=SL124453093-239630"
  },
  "r451": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "405",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817"
  },
  "r452": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "825",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=123345438&loc=d3e61044-112788"
  },
  "r453": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(12))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r454": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(2))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r455": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(23)(a)(3))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r456": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(23)(a)(4))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r457": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(25))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r458": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(8))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r459": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03.(a),19)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r46": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.9)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r460": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03.1,2)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r461": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03.15)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r462": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(18))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r463": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(22))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r464": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(3)(b))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r465": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04.7)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r466": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4H",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=116884468&loc=SL65671331-158438"
  },
  "r467": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Subparagraph": "(d)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124506351&loc=SL117782755-158439"
  },
  "r468": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13H",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "40",
   "Subparagraph": "(a)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124504033&loc=SL117783719-158441"
  },
  "r469": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13H",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "40",
   "Subparagraph": "(b)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124504033&loc=SL117783719-158441"
  },
  "r47": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226024-175313"
  },
  "r470": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29F",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "40",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124504033&loc=SL117819544-158441"
  },
  "r471": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(a)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r472": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(b)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r473": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(e)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r474": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(f)(1)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r475": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(f)(2)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r476": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(1)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r477": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(i)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r478": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(ii)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r479": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(iii)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r48": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "21",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226049-175313"
  },
  "r480": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(iv)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r481": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(h)(1)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r482": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(h)(2)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124501264&loc=SL117420844-207641"
  },
  "r483": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "25",
   "SubTopic": "720",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=35755714&loc=d3e28434-158551"
  },
  "r484": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "805",
   "Subparagraph": "(a)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=124505872&loc=d3e30806-158569"
  },
  "r485": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "805",
   "Topic": "944",
   "URI": "http://asc.fasb.org/subtopic&trid=2560393"
  },
  "r486": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column B)(Footnote 1))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r487": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column B)(Footnote 6))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r488": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column B)(Footnote 7))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r489": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column C)(Footnote 1))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r49": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313"
  },
  "r490": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column C)(Footnote 6))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r491": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column C)(Footnote 7))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r492": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column D)(Footnote 1))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r493": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column D)(Footnote 6))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r494": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-12B(Column D)(Footnote 7))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611197-123010"
  },
  "r495": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5D",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-13D(Column B)(Footnote 2))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=SL120429264-123010"
  },
  "r496": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5D",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-13D(Column C)(Footnote 2))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=SL120429264-123010"
  },
  "r497": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-15(Column A))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611379-123010"
  },
  "r498": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-15(Column B))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611379-123010"
  },
  "r499": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-15(Column C))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611379-123010"
  },
  "r5": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=124429488&loc=d3e326-107755"
  },
  "r50": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "210",
   "URI": "http://asc.fasb.org/topic&trid=2122208"
  },
  "r500": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "320",
   "Subparagraph": "(SX 210.12-15(Column D))",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=122147990&loc=d3e611379-123010"
  },
  "r501": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "310",
   "Subparagraph": "(SX 210.12-29(Footnote 4))",
   "Topic": "948",
   "URI": "http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014"
  },
  "r502": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "440",
   "Subparagraph": "(a)",
   "Topic": "954",
   "URI": "http://asc.fasb.org/extlink&oid=6491277&loc=d3e6429-115629"
  },
  "r503": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "360",
   "Subparagraph": "(d)",
   "Topic": "958",
   "URI": "http://asc.fasb.org/extlink&oid=120429125&loc=d3e99779-112916"
  },
  "r504": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "360",
   "Topic": "958",
   "URI": "http://asc.fasb.org/extlink&oid=120429125&loc=d3e99893-112916"
  },
  "r505": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Column B))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r506": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Column C))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r507": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Column D))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r508": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Column E))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r509": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Column F))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r51": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=SL7669646-108580"
  },
  "r510": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Column G))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r511": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Column H))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r512": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Column I))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r513": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "360",
   "Subparagraph": "(SX 210.12-28(Footnote 2))",
   "Topic": "970",
   "URI": "http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024"
  },
  "r514": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "310",
   "Subparagraph": "(c)",
   "Topic": "976",
   "URI": "http://asc.fasb.org/extlink&oid=6497875&loc=d3e22274-108663"
  },
  "r515": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "310",
   "Subparagraph": "(b)",
   "Topic": "978",
   "URI": "http://asc.fasb.org/extlink&oid=123360121&loc=d3e27327-108691"
  },
  "r516": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "985",
   "URI": "http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756"
  },
  "r517": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b"
  },
  "r518": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b-2"
  },
  "r519": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "d1-1"
  },
  "r52": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=SL7669646-108580"
  },
  "r520": {
   "Name": "Form 10-Q",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "308",
   "Subsection": "a"
  },
  "r521": {
   "Name": "Forms 10-K, 10-Q, 20-F",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "13",
   "Subsection": "a-1"
  },
  "r522": {
   "Name": "Regulation S-K (SK)",
   "Number": "229",
   "Paragraph": "(a)",
   "Publisher": "SEC",
   "Section": "1402"
  },
  "r523": {
   "Name": "Regulation S-T",
   "Number": "232",
   "Publisher": "SEC",
   "Section": "405"
  },
  "r524": {
   "Name": "Securities Act",
   "Number": "7A",
   "Publisher": "SEC",
   "Section": "B",
   "Subsection": "2"
  },
  "r525": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "848"
  },
  "r526": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "848"
  },
  "r527": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)(2)",
   "Topic": "848"
  },
  "r528": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)(3)(iii)(01)",
   "Topic": "848"
  },
  "r529": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(a)(3)(iii)(03)",
   "Topic": "848"
  },
  "r53": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=d3e637-108580"
  },
  "r54": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=d3e681-108580"
  },
  "r55": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=SL7669686-108580"
  },
  "r56": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=SL7669619-108580"
  },
  "r57": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=SL7669619-108580"
  },
  "r58": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=SL7669625-108580"
  },
  "r59": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=SL7669625-108580"
  },
  "r6": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760"
  },
  "r60": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124509347&loc=d3e557-108580"
  },
  "r61": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124431353&loc=SL124442407-227067"
  },
  "r62": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124431353&loc=SL124442411-227067"
  },
  "r63": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=124431353&loc=SL124452729-227067"
  },
  "r64": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(1))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227"
  },
  "r65": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(20))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227"
  },
  "r66": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(24))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227"
  },
  "r67": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(4))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227"
  },
  "r68": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.4)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227"
  },
  "r69": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.7)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227"
  },
  "r7": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "205",
   "URI": "http://asc.fasb.org/topic&trid=2122149"
  },
  "r70": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3151-108585"
  },
  "r71": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3179-108585"
  },
  "r72": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585"
  },
  "r73": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585"
  },
  "r74": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585"
  },
  "r75": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3291-108585"
  },
  "r76": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3291-108585"
  },
  "r77": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3000-108585"
  },
  "r78": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "24",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3521-108585"
  },
  "r79": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3536-108585"
  },
  "r8": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765"
  },
  "r80": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585"
  },
  "r81": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585"
  },
  "r82": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585"
  },
  "r83": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123570139&loc=d3e3044-108585"
  },
  "r84": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123431023&loc=d3e4273-108586"
  },
  "r85": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586"
  },
  "r86": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123431023&loc=d3e4313-108586"
  },
  "r87": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586"
  },
  "r88": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=123431023&loc=SL98516268-108586"
  },
  "r89": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=123372394&loc=d3e18726-107790"
  },
  "r9": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765"
  },
  "r90": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=123372394&loc=d3e18823-107790"
  },
  "r91": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=123372394&loc=d3e18823-107790"
  },
  "r92": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(d))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r93": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(e)(1))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r94": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(g)(1)(ii))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r95": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(m)(1)(ii)(A))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r96": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(m)(1)(iii))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r97": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(m)(2)(ii))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r98": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "235",
   "URI": "http://asc.fasb.org/topic&trid=2122369"
  },
  "r99": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "23",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=124436220&loc=d3e21914-107793"
  }
 },
 "version": "2.1"
}
