{
 "instance": {
  "evlo-20200630.htm": {
   "axisCustom": 1,
   "axisStandard": 19,
   "contextCount": 156,
   "dts": {
    "calculationLink": {
     "local": [
      "evlo-20200630_cal.xml"
     ]
    },
    "definitionLink": {
     "local": [
      "evlo-20200630_def.xml"
     ],
     "remote": [
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-eedm-def-2019-01-31.xml",
      "http://xbrl.fasb.org/srt/2019/elts/srt-eedm1-def-2019-01-31.xml"
     ]
    },
    "inline": {
     "local": [
      "evlo-20200630.htm"
     ]
    },
    "labelLink": {
     "local": [
      "evlo-20200630_lab.xml"
     ],
     "remote": [
      "https://xbrl.sec.gov/dei/2019/dei-doc-2019-01-31.xml",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-doc-2019-01-31.xml"
     ]
    },
    "presentationLink": {
     "local": [
      "evlo-20200630_pre.xml"
     ]
    },
    "referenceLink": {
     "remote": [
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-ref-2019-01-31.xml",
      "https://xbrl.sec.gov/dei/2019/dei-ref-2019-01-31.xml"
     ]
    },
    "schema": {
     "local": [
      "evlo-20200630.xsd"
     ],
     "remote": [
      "http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd",
      "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/dtr/type/numeric-2009-12-16.xsd",
      "http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd",
      "http://www.xbrl.org/2005/xbrldt-2005.xsd",
      "http://www.xbrl.org/2006/ref-2006-02-27.xsd",
      "http://xbrl.fasb.org/srt/2019/elts/srt-types-2019-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-roles-2019-01-31.xsd",
      "http://xbrl.fasb.org/srt/2019/elts/srt-roles-2019-01-31.xsd",
      "https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-types-2019-01-31.xsd",
      "https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd",
      "http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/net-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/reference-2009-12-16.xsd",
      "http://xbrl.fasb.org/us-gaap/2019/elts/us-parts-codification-2019-01-31.xsd",
      "http://www.xbrl.org/lrr/role/deprecated-2009-12-16.xsd"
     ]
    }
   },
   "elementCount": 399,
   "entityCount": 1,
   "hidden": {
    "http://evelobio.com/20200630": 1,
    "http://fasb.org/us-gaap/2019-01-31": 2,
    "http://xbrl.sec.gov/dei/2019-01-31": 6,
    "total": 9
   },
   "keyCustom": 35,
   "keyStandard": 272,
   "memberCustom": 21,
   "memberStandard": 27,
   "nsprefix": "evlo",
   "nsuri": "http://evelobio.com/20200630",
   "report": {
    "R1": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentQuarterlyReport",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "true",
     "longName": "0001001 - Document - Cover Page",
     "role": "http://evelobio.com/role/CoverPage",
     "shortName": "Cover Page",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentQuarterlyReport",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R10": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeasesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2108103 - Disclosure - Leases",
     "role": "http://evelobio.com/role/Leases",
     "shortName": "Leases",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeasesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R11": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2112104 - Disclosure - Fair Value Measurements",
     "role": "http://evelobio.com/role/FairValueMeasurements",
     "shortName": "Fair Value Measurements",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R12": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2115105 - Disclosure - Property and Equipment, Net",
     "role": "http://evelobio.com/role/PropertyandEquipmentNet",
     "shortName": "Property and Equipment, Net",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R13": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2119106 - Disclosure - Loan and Security Agreements",
     "role": "http://evelobio.com/role/LoanandSecurityAgreements",
     "shortName": "Loan and Security Agreements",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R14": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CollaborativeArrangementDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2123107 - Disclosure - In-License Agreements",
     "role": "http://evelobio.com/role/InLicenseAgreements",
     "shortName": "In-License Agreements",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CollaborativeArrangementDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R15": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CommitmentsAndContingenciesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2125108 - Disclosure - Commitments and Contingencies",
     "role": "http://evelobio.com/role/CommitmentsandContingencies",
     "shortName": "Commitments and Contingencies",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CommitmentsAndContingenciesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R16": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2127109 - Disclosure - Stockholders\u2019 Equity",
     "role": "http://evelobio.com/role/StockholdersEquity",
     "shortName": "Stockholders\u2019 Equity",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R17": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2129110 - Disclosure - Stock-Based Compensation",
     "role": "http://evelobio.com/role/StockBasedCompensation",
     "shortName": "Stock-Based Compensation",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R18": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:IncomeTaxDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2134111 - Disclosure - Income Taxes",
     "role": "http://evelobio.com/role/IncomeTaxes",
     "shortName": "Income Taxes",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:IncomeTaxDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R19": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:EarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2137112 - Disclosure - Net Loss Per Share",
     "role": "http://evelobio.com/role/NetLossPerShare",
     "shortName": "Net Loss Per Share",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:EarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R2": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CashAndCashEquivalentsAtCarryingValue",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1001002 - Statement - Condensed Consolidated Balance Sheets",
     "role": "http://evelobio.com/role/CondensedConsolidatedBalanceSheets",
     "shortName": "Condensed Consolidated Balance Sheets",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "lang": "en-US",
      "name": "us-gaap:PrepaidExpenseAndOtherAssetsCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R20": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:RelatedPartyTransactionsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2140113 - Disclosure - Related Party Transactions",
     "role": "http://evelobio.com/role/RelatedPartyTransactions",
     "shortName": "Related Party Transactions",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:RelatedPartyTransactionsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R21": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "evlo:SubstantialDoubtAboutGoingConcernPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2204201 - Disclosure - Summary of Significant Accounting Policies (Policies)",
     "role": "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies",
     "shortName": "Summary of Significant Accounting Policies (Policies)",
     "subGroupType": "policies",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "evlo:SubstantialDoubtAboutGoingConcernPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R22": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:IncomeTaxPolicyTextBlock",
      "reportCount": 1,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2236202 - Disclosure - Income Taxes (Policies)",
     "role": "http://evelobio.com/role/IncomeTaxesPolicies",
     "shortName": "Income Taxes (Policies)",
     "subGroupType": "policies",
     "uniqueAnchor": null
    },
    "R23": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfCashAndCashEquivalentsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2305301 - Disclosure - Summary of Significant Accounting Policies (Tables)",
     "role": "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesTables",
     "shortName": "Summary of Significant Accounting Policies (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfCashAndCashEquivalentsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R24": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2309302 - Disclosure - Leases (Tables)",
     "role": "http://evelobio.com/role/LeasesTables",
     "shortName": "Leases (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R25": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2313303 - Disclosure - Fair Value Measurements (Tables)",
     "role": "http://evelobio.com/role/FairValueMeasurementsTables",
     "shortName": "Fair Value Measurements (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R26": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2316304 - Disclosure - Property and Equipment, Net (Tables)",
     "role": "http://evelobio.com/role/PropertyandEquipmentNetTables",
     "shortName": "Property and Equipment, Net (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R27": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfMaturitiesOfLongTermDebtTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2320305 - Disclosure - Loan and Security Agreements (Tables)",
     "role": "http://evelobio.com/role/LoanandSecurityAgreementsTables",
     "shortName": "Loan and Security Agreements (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfMaturitiesOfLongTermDebtTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R28": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2330306 - Disclosure - Stock-Based Compensation (Tables)",
     "role": "http://evelobio.com/role/StockBasedCompensationTables",
     "shortName": "Stock-Based Compensation (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R29": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2338307 - Disclosure - Net Loss Per Share (Tables)",
     "role": "http://evelobio.com/role/NetLossPerShareTables",
     "shortName": "Net Loss Per Share (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R3": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:PreferredStockParOrStatedValuePerShare",
       "span",
       "div",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PreferredStockParOrStatedValuePerShare",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usdPerShare",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1002003 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)",
     "role": "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical",
     "shortName": "Condensed Consolidated Balance Sheets (Parenthetical)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:PreferredStockParOrStatedValuePerShare",
       "span",
       "div",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PreferredStockParOrStatedValuePerShare",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usdPerShare",
      "xsiNil": "false"
     }
    },
    "R30": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ProceedsFromIssuanceOfCommonStock",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2402401 - Disclosure - Organization - Additional Information (Details)",
     "role": "http://evelobio.com/role/OrganizationAdditionalInformationDetails",
     "shortName": "Organization - Additional Information (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "if724534107334d66a95c7d8b31069d9c_D20200601-20200630",
      "decimals": "INF",
      "lang": "en-US",
      "name": "us-gaap:SaleOfStockNumberOfSharesIssuedInTransaction",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     }
    },
    "R31": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ComprehensiveIncomeNetOfTax",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2406402 - Disclosure - Summary of Significant Accounting Policies - Narrative (Details)",
     "role": "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails",
     "shortName": "Summary of Significant Accounting Policies - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:SegmentReportingPolicyPolicyTextBlock",
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "INF",
      "lang": "en-US",
      "name": "us-gaap:NumberOfOperatingSegments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "segment",
      "xsiNil": "false"
     }
    },
    "R32": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:Cash",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2407403 - Disclosure - Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details)",
     "role": "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails",
     "shortName": "Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "ix:continuation",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:Cash",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R33": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "ifbfed296112e4881a1b8de480084852f_I20180131",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AreaOfLand",
      "reportCount": 1,
      "unique": true,
      "unitRef": "sqft",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2410404 - Disclosure - Leases - Narrative (Details)",
     "role": "http://evelobio.com/role/LeasesNarrativeDetails",
     "shortName": "Leases - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "ifbfed296112e4881a1b8de480084852f_I20180131",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AreaOfLand",
      "reportCount": 1,
      "unique": true,
      "unitRef": "sqft",
      "xsiNil": "false"
     }
    },
    "R34": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2411405 - Disclosure - Leases - Schedule of Minimum Aggregate Future Lease Commitments (Details)",
     "role": "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails",
     "shortName": "Leases - Schedule of Minimum Aggregate Future Lease Commitments (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R35": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AssetsFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2414406 - Disclosure - Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value (Details)",
     "role": "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails",
     "shortName": "Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AssetsFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R36": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PropertyPlantAndEquipmentTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2417407 - Disclosure - Property and Equipment, Net - Summary of Property and Equipment (Details)",
     "role": "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails",
     "shortName": "Property and Equipment, Net - Summary of Property and Equipment (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:PropertyPlantAndEquipmentTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:PropertyPlantAndEquipmentGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R37": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:Depreciation",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2418408 - Disclosure - Property and Equipment, Net - Narrative (Details)",
     "role": "http://evelobio.com/role/PropertyandEquipmentNetNarrativeDetails",
     "shortName": "Property and Equipment, Net - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:Depreciation",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R38": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i64cd7d5b8daa46a8a745433c4ed5d8b3_I20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2421409 - Disclosure - Loan and Security Agreements - Narrative (Details)",
     "role": "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails",
     "shortName": "Loan and Security Agreements - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i6f6742c390cf4a7c8c16dbb17737d7a7_D20190401-20190630",
      "decimals": "-5",
      "lang": "en-US",
      "name": "us-gaap:InterestExpenseDebt",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R39": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfMaturitiesOfLongTermDebtTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LongTermDebt",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2422410 - Disclosure - Loan and Security Agreements - Schedule of Minimum Aggregate Future Loan Payments (Details)",
     "role": "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails",
     "shortName": "Loan and Security Agreements - Schedule of Minimum Aggregate Future Loan Payments (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfMaturitiesOfLongTermDebtTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i8c8b64cb5e8046c9920aa96cd7146ba3_I20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:LongTermDebt",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R4": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ResearchAndDevelopmentExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1003004 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss",
     "role": "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss",
     "shortName": "Condensed Consolidated Statements of Operations and Comprehensive Loss",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ResearchAndDevelopmentExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R40": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "id6fd6e27b4b14ffe800609c45eb788da_D20170806-20170806",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "evlo:NonRefundableUpfrontFee",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2424411 - Disclosure - In-License Agreements - Narrative (Details)",
     "role": "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails",
     "shortName": "In-License Agreements - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "id6fd6e27b4b14ffe800609c45eb788da_D20170806-20170806",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "evlo:NonRefundableUpfrontFee",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R41": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i9f6331a337ac4b6ebc98502151c68c6d_D20190701-20190731",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "evlo:CollaborationArrangementTerm",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2426412 - Disclosure - Commitments and Contingencies - Narrative (Details)",
     "role": "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails",
     "shortName": "Commitments and Contingencies - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i9f6331a337ac4b6ebc98502151c68c6d_D20190701-20190731",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "evlo:CollaborationArrangementTerm",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R42": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ProceedsFromIssuanceOfCommonStock",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2428413 - Disclosure - Stockholders\u2019 Equity (Details)",
     "role": "http://evelobio.com/role/StockholdersEquityDetails",
     "shortName": "Stockholders\u2019 Equity (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i7dab7d28c943459ba35c41db77e49b4f_I20190603",
      "decimals": "INF",
      "lang": "en-US",
      "name": "evlo:SaleOfStockMaximumValueofSharesIssuedinTransaction",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R43": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod",
      "reportCount": 1,
      "unitRef": "shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2431414 - Disclosure - Stock-Based Compensation - Narrative (Details)",
     "role": "http://evelobio.com/role/StockBasedCompensationNarrativeDetails",
     "shortName": "Stock-Based Compensation - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "2",
      "lang": "en-US",
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usdPerShare",
      "xsiNil": "false"
     }
    },
    "R44": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AllocatedShareBasedCompensationExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2432415 - Disclosure - Stock-Based Compensation - Summary of Stock-based Compensation Expense (Details)",
     "role": "http://evelobio.com/role/StockBasedCompensationSummaryofStockbasedCompensationExpenseDetails",
     "shortName": "Stock-Based Compensation - Summary of Stock-based Compensation Expense (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AllocatedShareBasedCompensationExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R45": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i2b28e783b0e347a8ae6fd4be867336c9_I20191231",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2433416 - Disclosure - Stock-Based Compensation - Summary of Stock Option Activity (Details)",
     "role": "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails",
     "shortName": "Stock-Based Compensation - Summary of Stock Option Activity (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i2b28e783b0e347a8ae6fd4be867336c9_I20191231",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     }
    },
    "R46": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:IncomeTaxExpenseBenefit",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2435417 - Disclosure - Income Taxes (Details)",
     "role": "http://evelobio.com/role/IncomeTaxesDetails",
     "shortName": "Income Taxes (Details)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R47": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "0",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2439418 - Disclosure - Net Loss Per Share - Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-Average Shares Outstanding (Details)",
     "role": "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails",
     "shortName": "Net Loss Per Share - Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-Average Shares Outstanding (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "0",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     }
    },
    "R48": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "-5",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OperatingLeaseLeaseIncomeLeasePayments",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2441419 - Disclosure - Related Party Transactions - Narrative (Details)",
     "role": "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails",
     "shortName": "Related Party Transactions - Narrative (Details)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i005cf7a55ded47d39fd63763fd1c838b_D20200101-20200630",
      "decimals": "-5",
      "lang": "en-US",
      "name": "us-gaap:RelatedPartyTransactionAmountsOfTransaction",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R5": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i0b96c993180a43c68279993f9bd389da_D20200401-20200630",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent",
      "reportCount": 1,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1004005 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss (Parenthetical)",
     "role": "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLossParenthetical",
     "shortName": "Condensed Consolidated Statements of Operations and Comprehensive Loss (Parenthetical)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": null
    },
    "R6": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "i913f3780754743bb97406b947f59c65d_I20181231",
      "decimals": "INF",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SharesOutstanding",
      "reportCount": 1,
      "unitRef": "shares",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1005006 - Statement - Condensed Consolidated Statements of Preferred Stock and Stockholders\u2019 Equity",
     "role": "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity",
     "shortName": "Condensed Consolidated Statements of Preferred Stock and Stockholders\u2019 Equity",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "ie785117cfa1d4418aa16b6d272f17328_D20190101-20190331",
      "decimals": "INF",
      "lang": "en-US",
      "name": "us-gaap:StockIssuedDuringPeriodSharesRestrictedStockAwardGross",
      "reportCount": 1,
      "unique": true,
      "unitRef": "shares",
      "xsiNil": "false"
     }
    },
    "R7": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ProfitLoss",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "1006007 - Statement - Condensed Consolidated Statements of Cash Flows",
     "role": "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows",
     "shortName": "Condensed Consolidated Statements of Cash Flows",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": "-3",
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ProfitLoss",
      "reportCount": 1,
      "unique": true,
      "unitRef": "usd",
      "xsiNil": "false"
     }
    },
    "R8": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2101101 - Disclosure - Organization",
     "role": "http://evelobio.com/role/Organization",
     "shortName": "Organization",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R9": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SignificantAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "2103102 - Disclosure - Summary of Significant Accounting Policies",
     "role": "http://evelobio.com/role/SummaryofSignificantAccountingPolicies",
     "shortName": "Summary of Significant Accounting Policies",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "div",
       "body",
       "html"
      ],
      "baseRef": "evlo-20200630.htm",
      "contextRef": "iae7b634efaeb444186810fe8d09e4785_D20200101-20200630",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SignificantAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    }
   },
   "segmentCount": 49,
   "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_CoverAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Cover page.",
        "label": "Cover [Abstract]"
       }
      }
     },
     "localname": "CoverAbstract",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "fiscalPeriodItemType"
    },
    "dei_DocumentFiscalYearFocus": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "This is focus fiscal year of the document report in CCYY 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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "gYearItemType"
    },
    "dei_DocumentPeriodEndDate": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented.  If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.",
        "label": "Document Period End Date",
        "terseLabel": "Document Period End Date"
       }
      }
     },
     "localname": "DocumentPeriodEndDate",
     "nsuri": "http://xbrl.sec.gov/dei/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "dateItemType"
    },
    "dei_DocumentQuarterlyReport": {
     "auth_ref": [
      "r277"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_DocumentTransitionReport": {
     "auth_ref": [
      "r278"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "stateOrProvinceItemType"
    },
    "dei_EntityCentralIndexKey": {
     "auth_ref": [
      "r279"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityEmergingGrowthCompany": {
     "auth_ref": [
      "r279"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityExTransitionPeriod": {
     "auth_ref": [
      "r281"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "fileNumberItemType"
    },
    "dei_EntityFilerCategory": {
     "auth_ref": [
      "r279"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "edgarStateCountryItemType"
    },
    "dei_EntityInteractiveDataCurrent": {
     "auth_ref": [
      "r280"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityRegistrantName": {
     "auth_ref": [
      "r279"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityShellCompany": {
     "auth_ref": [
      "r279"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntitySmallBusiness": {
     "auth_ref": [
      "r279"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityTaxIdentificationNumber": {
     "auth_ref": [
      "r279"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_Security12bTitle": {
     "auth_ref": [
      "r275"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "securityTitleItemType"
    },
    "dei_SecurityExchangeName": {
     "auth_ref": [
      "r276"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CoverPage"
     ],
     "xbrltype": "tradingSymbolItemType"
    },
    "evlo_A2016CreditFacilityMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "2016 Credit Facility [Member]",
        "label": "2016 Credit Facility [Member]",
        "terseLabel": "2016 Credit Facility"
       }
      }
     },
     "localname": "A2016CreditFacilityMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_A2019CreditFacilityMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "2019 Credit Facility [Member]",
        "label": "2019 Credit Facility [Member]",
        "terseLabel": "2019 Credit Facility"
       }
      }
     },
     "localname": "A2019CreditFacilityMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_AggregateAmountDueUnderCollaborativeArrangement": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate Amount Due Under Collaborative Arrangement",
        "label": "Aggregate Amount Due Under Collaborative Arrangement",
        "terseLabel": "Aggregate amount due under collaborative arrangement"
       }
      }
     },
     "localname": "AggregateAmountDueUnderCollaborativeArrangement",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_AnnualAmountDueUnderCollaborativeArrangement": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Annual Amount Due Under Collaborative Arrangement",
        "label": "Annual Amount Due Under Collaborative Arrangement",
        "terseLabel": "Annual amount due under collaborative arrangement"
       }
      }
     },
     "localname": "AnnualAmountDueUnderCollaborativeArrangement",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_BioseIndustrieMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Biose Industrie.",
        "label": "Biose Industrie [Member]",
        "terseLabel": "Biose Industrie"
       }
      }
     },
     "localname": "BioseIndustrieMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_CollaborationArrangementTerm": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Collaboration Arrangement, Term",
        "label": "Collaboration Arrangement, Term",
        "terseLabel": "Term of collaboration arrangement"
       }
      }
     },
     "localname": "CollaborationArrangementTerm",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "evlo_CollaborativeArrangementPeriodOfInactiveManufacturingServices": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Collaborative Arrangement, Period Of Inactive Manufacturing Services",
        "label": "Collaborative Arrangement, Period Of Inactive Manufacturing Services",
        "terseLabel": "Period of inactive manufacturing services causing termination under collaborative arrangement"
       }
      }
     },
     "localname": "CollaborativeArrangementPeriodOfInactiveManufacturingServices",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "evlo_CommitmentAndContingenciesLineItems": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commitment and contingencies.",
        "label": "Commitment And Contingencies [Line Items]",
        "terseLabel": "Commitment And Contingencies [Line Items]"
       }
      }
     },
     "localname": "CommitmentAndContingenciesLineItems",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "evlo_CommitmentAndContingenciesTable": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Commitment And Contingencies [Table]",
        "label": "Commitment And Contingencies [Table]",
        "terseLabel": "Commitment And Contingencies [Table]"
       }
      }
     },
     "localname": "CommitmentAndContingenciesTable",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "evlo_CommonStockOutstandingPercentageToBeDeclaredAsAnIncreaseInGrants": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Common stock outstanding percentage to be declared as an increase in grants.",
        "label": "Common stock outstanding percentage to be declared as an increase in grants",
        "terseLabel": "Common stock outstanding percentage to be declared as an increase in grants"
       }
      }
     },
     "localname": "CommonStockOutstandingPercentageToBeDeclaredAsAnIncreaseInGrants",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "evlo_ComputersAndSoftwareMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Computers and software.",
        "label": "Computers And Software [Member]",
        "terseLabel": "Computers and software"
       }
      }
     },
     "localname": "ComputersAndSoftwareMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_ConsultingAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Consulting Agreement [Member]",
        "label": "Consulting Agreement [Member]",
        "terseLabel": "Consulting Agreement"
       }
      }
     },
     "localname": "ConsultingAgreementMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_DebtInstrumentAnniversaryForDeterminingPrepaymentFeePercentage": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt Instrument, Anniversary For Determining Prepayment Fee Percentage",
        "label": "Debt Instrument, Anniversary For Determining Prepayment Fee Percentage",
        "terseLabel": "Anniversary of funding date for determining prepayment fee percentage"
       }
      }
     },
     "localname": "DebtInstrumentAnniversaryForDeterminingPrepaymentFeePercentage",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "evlo_DebtInstrumentDebtDefaultPercentage": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt Instrument, Debt Default, Percentage",
        "label": "Debt Instrument, Debt Default, Percentage",
        "terseLabel": "Debt default interest rate per annum"
       }
      }
     },
     "localname": "DebtInstrumentDebtDefaultPercentage",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "evlo_DebtInstrumentPrepaymentFeePercentageAfterSpecifiedPeriodOne": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt instrument prepayment fee percentage after specified period one.",
        "label": "Debt Instrument Prepayment Fee Percentage After Specified Period One",
        "terseLabel": "Prepayment fee percentage after specified period"
       }
      }
     },
     "localname": "DebtInstrumentPrepaymentFeePercentageAfterSpecifiedPeriodOne",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "evlo_DebtInstrumentPrepaymentFeePercentageOnPrincipal": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt instrument prepayment fee percentage on principal.",
        "label": "Debt Instrument Prepayment Fee Percentage On Principal",
        "terseLabel": "Prepayment fee percentage"
       }
      }
     },
     "localname": "DebtInstrumentPrepaymentFeePercentageOnPrincipal",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "evlo_DebtInstrumentRepaymentOrPrepaymentFeePercentage": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Debt Instrument, Repayment Or Prepayment Fee Percentage",
        "label": "Debt Instrument, Repayment Or Prepayment Fee Percentage",
        "terseLabel": "Final payment under agreement as a percentage of loans borrowed"
       }
      }
     },
     "localname": "DebtInstrumentRepaymentOrPrepaymentFeePercentage",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "evlo_DeferredPublicOfferingCostsIncludedInAccountsPayableAndAccruedExpenses": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Deferred Public Offering Costs Included In Accounts Payable And Accrued Expenses",
        "label": "Deferred Public Offering Costs Included In Accounts Payable And Accrued Expenses",
        "terseLabel": "Deferred financing and public offering costs in accounts payable and accrued expenses"
       }
      }
     },
     "localname": "DeferredPublicOfferingCostsIncludedInAccountsPayableAndAccruedExpenses",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_EmergingGrowthCompanyStatusPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Emerging growth company status.",
        "label": "Emerging Growth Company Status [Policy Text Block]",
        "terseLabel": "Emerging Growth Company Status"
       }
      }
     },
     "localname": "EmergingGrowthCompanyStatusPolicyTextBlock",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "evlo_ExclusivityAndCommitmentAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Exclusivity and commitment agreement.",
        "label": "Exclusivity and Commitment Agreement [Member]",
        "terseLabel": "Exclusivity and Commitment Agreement"
       }
      }
     },
     "localname": "ExclusivityAndCommitmentAgreementMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_IncreaseDecreaseInOperatingLeaseLiability": {
     "auth_ref": [],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 11.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Increase (Decrease) In Operating Lease Liability",
        "label": "Increase (Decrease) In Operating Lease Liability",
        "terseLabel": "Operating lease liabilities"
       }
      }
     },
     "localname": "IncreaseDecreaseInOperatingLeaseLiability",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_JuneOfferingMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "June Offering",
        "label": "June Offering [Member]",
        "terseLabel": "June Offering"
       }
      }
     },
     "localname": "JuneOfferingMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails",
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingAfterYearFour": {
     "auth_ref": [],
     "calculation": {
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails": {
       "order": 5.0,
       "parentTag": "us-gaap_LongTermDebt",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Long-term Debt, Maturities, Repayments of Principal in Rolling After Year Four",
        "label": "Long-term Debt, Maturities, Repayments of Principal in Rolling After Year Four",
        "terseLabel": "Thereafter"
       }
      }
     },
     "localname": "LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingAfterYearFour",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_MilestonePaymentsForDevelopmentAndCommercializationOfLicensedProducts": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Milestone Payments For Development And Commercialization Of Licensed Products",
        "label": "Milestone Payments For Development And Commercialization Of Licensed Products",
        "terseLabel": "Milestone payments for development and commercialization of licensed products"
       }
      }
     },
     "localname": "MilestonePaymentsForDevelopmentAndCommercializationOfLicensedProducts",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_MilestonePaymentsOfDevelopmentRegulatoryAndCommercialEvent": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Milestone payments of development, regulatory, and commercial event.",
        "label": "Milestone Payments of Development, Regulatory, and Commercial Event",
        "terseLabel": "Milestone payments upon achievement of certain development, regulatory, and commercial events"
       }
      }
     },
     "localname": "MilestonePaymentsOfDevelopmentRegulatoryAndCommercialEvent",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_NonCashInterestExpense": {
     "auth_ref": [],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 5.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Non-cash interest expense.",
        "label": "Non Cash Interest Expense",
        "terseLabel": "Non-cash interest expense"
       }
      }
     },
     "localname": "NonCashInterestExpense",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_NonCashOperatingLeaseExpense": {
     "auth_ref": [],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 6.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Non-Cash Operating Lease Expense",
        "label": "Non-Cash Operating Lease Expense",
        "terseLabel": "Non-cash lease expense"
       }
      }
     },
     "localname": "NonCashOperatingLeaseExpense",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_NonEmployeeOptionsMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Non Employee Options [Member]",
        "label": "Non Employee Options [Member]",
        "terseLabel": "Non-Employee Options"
       }
      }
     },
     "localname": "NonEmployeeOptionsMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_NonRefundableUpfrontFee": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Non refundable upfront fee.",
        "label": "Non Refundable Upfront Fee",
        "terseLabel": "Non-refundable upfront fee"
       }
      }
     },
     "localname": "NonRefundableUpfrontFee",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_RegistrationStatementMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Registration Statement [Member]",
        "label": "Registration Statement [Member]",
        "terseLabel": "Registration Statement"
       }
      }
     },
     "localname": "RegistrationStatementMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_RelatedPartyTransactionAnnualCashConsultingFee": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Related Party Transaction, Annual Cash Consulting Fee",
        "label": "Related Party Transaction, Annual Cash Consulting Fee",
        "terseLabel": "Aggregate annual cash consulting fee"
       }
      }
     },
     "localname": "RelatedPartyTransactionAnnualCashConsultingFee",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_RelatedPartyTransactionAnnualSharebasedPaymentAwardOptionsGrantDateFairMarketValue": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Related Party Transaction, Annual Share-based Payment Award, Options, Grant Date Fair Market Value",
        "label": "Related Party Transaction, Annual Share-based Payment Award, Options, Grant Date Fair Market Value",
        "terseLabel": "Aggregate grant date fair value"
       }
      }
     },
     "localname": "RelatedPartyTransactionAnnualSharebasedPaymentAwardOptionsGrantDateFairMarketValue",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_RelatedPartyTransactionConsultingContractTerm": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Related Party Transaction, Consulting Contract, Term",
        "label": "Related Party Transaction, Consulting Contract, Term",
        "terseLabel": "Consulting arrangement term"
       }
      }
     },
     "localname": "RelatedPartyTransactionConsultingContractTerm",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "evlo_RelatedPartyTransactionConsultingContractTerminationNoticeTerm": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Related Party Transaction, Consulting Contract, Termination Notice, Term",
        "label": "Related Party Transaction, Consulting Contract, Termination Notice, Term",
        "terseLabel": "Termination notice period of consulting arrangement"
       }
      }
     },
     "localname": "RelatedPartyTransactionConsultingContractTerminationNoticeTerm",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "evlo_RelatedPartyTransactionConsultingContractTerminationNoticeUponBreachofContractTerm": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Related Party Transaction, Consulting Contract, Termination Notice Upon Breach of Contract, Term",
        "label": "Related Party Transaction, Consulting Contract, Termination Notice Upon Breach of Contract, Term",
        "terseLabel": "Termination notice period by non-breaching party in event of a breach"
       }
      }
     },
     "localname": "RelatedPartyTransactionConsultingContractTerminationNoticeUponBreachofContractTerm",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "evlo_SaccoS.r.l.Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sacco S.r.l. [Member]",
        "label": "Sacco S.r.l. [Member]",
        "terseLabel": "Sacco"
       }
      }
     },
     "localname": "SaccoS.r.l.Member",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_SaleOfStockConsiderationReceivedTerm": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sale Of Stock, Consideration Received, Term",
        "label": "Sale Of Stock, Consideration Received, Term",
        "terseLabel": "Sale of stock, term"
       }
      }
     },
     "localname": "SaleOfStockConsiderationReceivedTerm",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "evlo_SaleOfStockMaximumValueofSharesIssuedinTransaction": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sale Of Stock, Maximum Value of Shares Issued in Transaction",
        "label": "Sale Of Stock, Maximum Value of Shares Issued in Transaction",
        "terseLabel": "Registration of equity instruments, aggregate authorized amount"
       }
      }
     },
     "localname": "SaleOfStockMaximumValueofSharesIssuedinTransaction",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_SalesAgreementCowenAndCompanyLLCMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sales Agreement, Cowen And Company, LLC [Member]",
        "label": "Sales Agreement, Cowen And Company, LLC [Member]",
        "terseLabel": "Sales Agreement, Cowen And Company, LLC"
       }
      }
     },
     "localname": "SalesAgreementCowenAndCompanyLLCMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_SecurityAndLoanAgreementNumberOfTranches": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Security And Loan Agreement, Number Of Tranches",
        "label": "Security And Loan Agreement, Number Of Tranches",
        "terseLabel": "Number of tranches"
       }
      }
     },
     "localname": "SecurityAndLoanAgreementNumberOfTranches",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "evlo_SecurityAndLoanAgreementTrancheOneMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Security And Loan Agreement, Tranche One [Member]",
        "label": "Security And Loan Agreement, Tranche One [Member]",
        "terseLabel": "Security And Loan Agreement, Tranche One"
       }
      }
     },
     "localname": "SecurityAndLoanAgreementTrancheOneMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_SecurityAndLoanAgreementTrancheThreeMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Security And Loan Agreement, Tranche Three [Member]",
        "label": "Security And Loan Agreement, Tranche Three [Member]",
        "terseLabel": "Security And Loan Agreement, Tranche Three"
       }
      }
     },
     "localname": "SecurityAndLoanAgreementTrancheThreeMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_SecurityAndLoanAgreementTrancheTwoMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Security And Loan Agreement, Tranche Two [Member]",
        "label": "Security And Loan Agreement, Tranche Two [Member]",
        "terseLabel": "Security And Loan Agreement, Tranche Two"
       }
      }
     },
     "localname": "SecurityAndLoanAgreementTrancheTwoMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_SecurityAndLoanAgreementTranchesAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Security And Loan Agreement, Tranches [Axis]",
        "label": "Security And Loan Agreement, Tranches [Axis]",
        "terseLabel": "Security And Loan Agreement, Tranches [Axis]"
       }
      }
     },
     "localname": "SecurityAndLoanAgreementTranchesAxis",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "evlo_SecurityAndLoanAgreementTranchesDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "[Domain] for Security And Loan Agreement, Tranches [Axis]",
        "label": "Security And Loan Agreement, Tranches [Domain]",
        "terseLabel": "Security And Loan Agreement, Tranches [Domain]"
       }
      }
     },
     "localname": "SecurityAndLoanAgreementTranchesDomain",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedIncreaseDecrease": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized Increase Decrease",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized Increase Decrease",
        "terseLabel": "Number of shares no longer authorized (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedIncreaseDecrease",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "evlo_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesRepurchased": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Share Based Compensation Arrangement By Share Based Payment Award, Number Of Shares Repurchased",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award, Number Of Shares Repurchased",
        "terseLabel": "Number of shares repurchased (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesRepurchased",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "evlo_SharebasedCompensationArrangementbySharebasedPaymentAwardAwardVestingPeriodNumberOfMonthlyInstallments": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period, Number Of Monthly Installments",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period, Number Of Monthly Installments",
        "terseLabel": "Number of equal monthly installments"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementbySharebasedPaymentAwardAwardVestingPeriodNumberOfMonthlyInstallments",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "integerItemType"
    },
    "evlo_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsandNonOptionEquityInstrumentsExercised": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sharebased Compensation Arrangementby Sharebased Payment Award Optionsand Non Option Equity Instruments Exercised",
        "label": "Sharebased Compensation Arrangementby Sharebased Payment Award Optionsand Non Option Equity Instruments Exercised",
        "terseLabel": "Number of shares, options and other equity awards exercised (in shares)"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsandNonOptionEquityInstrumentsExercised",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "evlo_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsandNonOptionEquityInstrumentsForfeitures": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sharebased Compensation Arrangementby Sharebased Payment Award Optionsand Non Option Equity Instruments Forfeitures",
        "label": "Sharebased Compensation Arrangementby Sharebased Payment Award Optionsand Non Option Equity Instruments Forfeitures",
        "terseLabel": "Number of shares, options and other equity awards canceled (in shares)"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsandNonOptionEquityInstrumentsForfeitures",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "evlo_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsandNonOptionEquityInstrumentsGranted": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Sharebased Compensation Arrangementby Sharebased Payment Award Optionsand Non Option Equity Instruments Granted",
        "label": "Sharebased Compensation Arrangementby Sharebased Payment Award Optionsand Non Option Equity Instruments Granted",
        "terseLabel": "Number of shares, options and other equity awards granted (in shares)"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsandNonOptionEquityInstrumentsGranted",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "evlo_SocialSecurityTaxEmployerDeferralCARESAct": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Social Security Tax, Employer, Deferral, CARES Act",
        "label": "Social Security Tax, Employer, Deferral, CARES Act",
        "terseLabel": "Deferred payroll taxes related to CARES Act"
       }
      }
     },
     "localname": "SocialSecurityTaxEmployerDeferralCARESAct",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/IncomeTaxesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "evlo_SubstantialDoubtAboutGoingConcernPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Substantial Doubt About Going Concern",
        "label": "Substantial Doubt About Going Concern [Policy Text Block]",
        "terseLabel": "Going Concern"
       }
      }
     },
     "localname": "SubstantialDoubtAboutGoingConcernPolicyTextBlock",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "evlo_TwoThousandAndEighteenStockIncentivePlanMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "2018 stock incentive plan.",
        "label": "Two Thousand And Eighteen Stock Incentive Plan [Member]",
        "terseLabel": "2018 Stock Incentive Plan"
       }
      }
     },
     "localname": "TwoThousandAndEighteenStockIncentivePlanMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_TwoThousandAndFifteenStockIncentivePlanMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Two thousand and fifteen stock incentive plan.",
        "label": "Two Thousand And Fifteen Stock Incentive Plan [Member]",
        "terseLabel": "2015 Stock Incentive Plan"
       }
      }
     },
     "localname": "TwoThousandAndFifteenStockIncentivePlanMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_TwoThousandSeventeenMayoLicenseAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "2017 Mayo license agreement.",
        "label": "Two Thousand Seventeen Mayo License Agreement [Member]",
        "terseLabel": "2017 Mayo License Agreement"
       }
      }
     },
     "localname": "TwoThousandSeventeenMayoLicenseAgreementMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_UniversityOfChicagoMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "University of Chicago.",
        "label": "University of Chicago [Member]",
        "terseLabel": "2016 University of Chicago Agreement"
       }
      }
     },
     "localname": "UniversityOfChicagoMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_UnvestedCommonStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Unvested common stock.",
        "label": "Unvested Common Stock [Member]",
        "terseLabel": "Unvested common stock from early exercise of options"
       }
      }
     },
     "localname": "UnvestedCommonStockMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_VL46Member": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "VL46.",
        "label": "V- L- 46 [Member]",
        "terseLabel": "VL46"
       }
      }
     },
     "localname": "VL46Member",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "evlo_WeatherdenLtdMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Weatherden Ltd.",
        "label": "Weatherden Ltd [Member]",
        "terseLabel": "Weatherden Ltd"
       }
      }
     },
     "localname": "WeatherdenLtdMember",
     "nsuri": "http://evelobio.com/20200630",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_BoardOfDirectorsChairmanMember": {
     "auth_ref": [
      "r105"
     ],
     "lang": {
      "en-US": {
       "role": {
        "label": "Board of Directors Chairman [Member]",
        "terseLabel": "Mr. Epstein"
       }
      }
     },
     "localname": "BoardOfDirectorsChairmanMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_CounterpartyNameAxis": {
     "auth_ref": [
      "r37",
      "r79"
     ],
     "lang": {
      "en-US": {
       "role": {
        "label": "Counterparty Name [Axis]",
        "terseLabel": "Counterparty Name [Axis]"
       }
      }
     },
     "localname": "CounterpartyNameAxis",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_MaximumMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Maximum [Member]",
        "terseLabel": "Maximum"
       }
      }
     },
     "localname": "MaximumMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MinimumMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Minimum [Member]",
        "terseLabel": "Minimum"
       }
      }
     },
     "localname": "MinimumMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RangeAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statistical Measurement [Axis]",
        "terseLabel": "Range [Axis]"
       }
      }
     },
     "localname": "RangeAxis",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_RangeMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statistical Measurement [Domain]",
        "terseLabel": "Range [Domain]"
       }
      }
     },
     "localname": "RangeMember",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RepurchaseAgreementCounterpartyNameDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Counterparty Name [Domain]",
        "terseLabel": "Counterparty Name [Domain]"
       }
      }
     },
     "localname": "RepurchaseAgreementCounterpartyNameDomain",
     "nsuri": "http://fasb.org/srt/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccountingPoliciesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Accounting Policies [Abstract]",
        "terseLabel": "Accounting Policies [Abstract]"
       }
      }
     },
     "localname": "AccountingPoliciesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccountingStandardsUpdate201602Member": {
     "auth_ref": [
      "r213"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Accounting Standards Update 2016-02 Leases (Topic 842).",
        "label": "Accounting Standards Update 2016-02 [Member]",
        "terseLabel": "Accounting Standards Update 2016-02"
       }
      }
     },
     "localname": "AccountingStandardsUpdate201602Member",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccountsPayableCurrent": {
     "auth_ref": [
      "r24"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "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 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"
       }
      }
     },
     "localname": "AccountsPayableCurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments": {
     "auth_ref": [
      "r68"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "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",
        "negatedTerseLabel": "Net (accretion of discount)/amortization of premium on marketable securities"
       }
      }
     },
     "localname": "AccretionAmortizationOfDiscountsAndPremiumsInvestments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccruedLiabilitiesCurrent": {
     "auth_ref": [
      "r27"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "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 expenses"
       }
      }
     },
     "localname": "AccruedLiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment": {
     "auth_ref": [
      "r22",
      "r119"
     ],
     "calculation": {
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails": {
       "order": 2.0,
       "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"
       }
      }
     },
     "localname": "AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeMember": {
     "auth_ref": [
      "r38",
      "r39",
      "r40",
      "r196"
     ],
     "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 Loss"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdditionalPaidInCapitalCommonStock": {
     "auth_ref": [
      "r13"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 3.0,
       "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",
        "terseLabel": "Additional paid-in capital"
       }
      }
     },
     "localname": "AdditionalPaidInCapitalCommonStock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AdditionalPaidInCapitalMember": {
     "auth_ref": [],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdjustmentsForNewAccountingPronouncementsAxis": {
     "auth_ref": [
      "r86"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by new accounting pronouncement.",
        "label": "Adjustments for New Accounting Pronouncements [Axis]",
        "terseLabel": "Adjustments for New Accounting Pronouncements [Axis]"
       }
      }
     },
     "localname": "AdjustmentsForNewAccountingPronouncementsAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue": {
     "auth_ref": [
      "r147",
      "r149",
      "r172",
      "r173"
     ],
     "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"
       }
      }
     },
     "localname": "AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AllocatedShareBasedCompensationExpense": {
     "auth_ref": [
      "r149",
      "r167",
      "r171"
     ],
     "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"
       }
      }
     },
     "localname": "AllocatedShareBasedCompensationExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockbasedCompensationExpenseDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount": {
     "auth_ref": [
      "r90"
     ],
     "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",
        "verboseLabel": "Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis": {
     "auth_ref": [
      "r90"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of antidilutive security.",
        "label": "Antidilutive Securities [Axis]",
        "terseLabel": "Antidilutive Securities [Axis]"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AntidilutiveSecuritiesNameDomain": {
     "auth_ref": [
      "r90"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AreaOfLand": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Area of land held.",
        "label": "Area of Land",
        "terseLabel": "Area of leased office and research development space (in square feet)"
       }
      }
     },
     "localname": "AreaOfLand",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesNarrativeDetails"
     ],
     "xbrltype": "areaItemType"
    },
    "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 [Domain]"
       }
      }
     },
     "localname": "ArrangementsAndNonarrangementTransactionsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_Assets": {
     "auth_ref": [
      "r103",
      "r254",
      "r262"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Assets [Abstract]",
        "terseLabel": "Assets"
       }
      }
     },
     "localname": "AssetsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AssetsCurrent": {
     "auth_ref": [
      "r1",
      "r2",
      "r36"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AssetsFairValueDisclosure": {
     "auth_ref": [
      "r202"
     ],
     "calculation": {
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.",
        "label": "Assets, Fair Value Disclosure",
        "totalLabel": "Total"
       }
      }
     },
     "localname": "AssetsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsFairValueDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Assets, Fair Value Disclosure [Abstract]",
        "terseLabel": "Assets:"
       }
      }
     },
     "localname": "AssetsFairValueDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AwardTypeAxis": {
     "auth_ref": [
      "r150",
      "r169"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of award under share-based payment arrangement.",
        "label": "Award Type [Axis]",
        "terseLabel": "Award Type [Axis]"
       }
      }
     },
     "localname": "AwardTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CapitalExpendituresIncurredButNotYetPaid": {
     "auth_ref": [
      "r72",
      "r73",
      "r74"
     ],
     "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": "Property and equipment additions in accounts payable and accrued expenses"
       }
      }
     },
     "localname": "CapitalExpendituresIncurredButNotYetPaid",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Cash": {
     "auth_ref": [
      "r20",
      "r271",
      "r272"
     ],
     "calculation": {
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_CashAndCashEquivalentsAtCarryingValue",
       "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. Excludes cash and cash equivalents within disposal group and discontinued operation.",
        "label": "Cash",
        "terseLabel": "Cash"
       }
      }
     },
     "localname": "Cash",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsAtCarryingValue": {
     "auth_ref": [
      "r0",
      "r20",
      "r69"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "parentTag": "us-gaap_AssetsCurrent",
       "weight": 1.0
      },
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents",
       "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",
        "terseLabel": "Cash and cash equivalents",
        "totalLabel": "Total cash and cash equivalents"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAtCarryingValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets",
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsFairValueDisclosure": {
     "auth_ref": [],
     "calculation": {
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_AssetsFairValueDisclosure",
       "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": "Cash and cash equivalents, fair value disclosure"
       }
      }
     },
     "localname": "CashAndCashEquivalentsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy": {
     "auth_ref": [
      "r5",
      "r70",
      "r76",
      "r253"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CashCashEquivalentsAndShortTermInvestments": {
     "auth_ref": [
      "r20"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.",
        "label": "Cash, Cash Equivalents, and Short-term Investments",
        "terseLabel": "Cash, cash equivalents and short-term investments"
       }
      }
     },
     "localname": "CashCashEquivalentsAndShortTermInvestments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents": {
     "auth_ref": [
      "r63",
      "r69",
      "r75"
     ],
     "calculation": {
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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 and restricted cash \u2013 end of period",
        "periodStartLabel": "Cash, cash equivalents and restricted cash \u2013 beginning of period",
        "totalLabel": "Cash, cash equivalents and restricted cash"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows",
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]",
        "terseLabel": "Cash and cash equivalents:"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect": {
     "auth_ref": [
      "r63",
      "r210"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "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 (decrease) increase in cash, cash equivalents and restricted cash"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CollaborativeArrangementDisclosureTextBlock": {
     "auth_ref": [
      "r186",
      "r187",
      "r189"
     ],
     "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": "In-License Agreements"
       }
      }
     },
     "localname": "CollaborativeArrangementDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreements"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CollaborativeArrangementMember": {
     "auth_ref": [
      "r188"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Contractual arrangement that involves two or more parties that both: (i) actively participate in a joint operating activity and (ii) are exposed to significant risks and rewards that depend on the commercial success of the joint operating activity.",
        "label": "Collaborative Arrangement [Member]",
        "terseLabel": "Collaborative Arrangement"
       }
      }
     },
     "localname": "CollaborativeArrangementMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommitmentsAndContingencies": {
     "auth_ref": [
      "r32",
      "r124",
      "r259",
      "r268"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Commitments and Contingencies Disclosure [Abstract]",
        "terseLabel": "Commitments and Contingencies Disclosure [Abstract]"
       }
      }
     },
     "localname": "CommitmentsAndContingenciesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureTextBlock": {
     "auth_ref": [
      "r123",
      "r125"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingencies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CommonStockMember": {
     "auth_ref": [],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommonStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r12"
     ],
     "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 (in dollars per share)"
       }
      }
     },
     "localname": "CommonStockParOrStatedValuePerShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CommonStockSharesAuthorized": {
     "auth_ref": [
      "r12"
     ],
     "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 (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesIssued": {
     "auth_ref": [
      "r12"
     ],
     "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",
        "verboseLabel": "Common stock, shares issued (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesOutstanding": {
     "auth_ref": [
      "r12",
      "r134"
     ],
     "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",
        "terseLabel": "Common stock, shares outstanding (in shares)"
       }
      }
     },
     "localname": "CommonStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockValue": {
     "auth_ref": [
      "r12"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "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",
        "terseLabel": "Common stock, $0.001 par value; 200,000,000 shares authorized; 46,173,415 and 32,232,258 shares issued and 46,136,643 and 32,170,605 shares outstanding at June 30, 2020 and December\u00a031, 2019, respectively"
       }
      }
     },
     "localname": "CommonStockValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ComprehensiveIncomeNetOfTax": {
     "auth_ref": [
      "r42",
      "r44",
      "r45"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "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",
        "negatedLabel": "Comprehensive loss",
        "totalLabel": "Comprehensive loss"
       }
      }
     },
     "localname": "ComprehensiveIncomeNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss",
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ComprehensiveIncomeNetOfTaxAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]",
        "terseLabel": "Comprehensive loss:"
       }
      }
     },
     "localname": "ComprehensiveIncomeNetOfTaxAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ConsolidationPolicyTextBlock": {
     "auth_ref": [
      "r76",
      "r192",
      "r199",
      "r200"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example, common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting.  The accounting policy may also address the accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.",
        "label": "Consolidation, Policy [Policy Text Block]",
        "terseLabel": "Principles of Consolidation"
       }
      }
     },
     "localname": "ConsolidationPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "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-process"
       }
      }
     },
     "localname": "ConstructionInProgressMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ContractualObligation": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.",
        "label": "Contractual Obligation",
        "terseLabel": "Amount due under license agreement"
       }
      }
     },
     "localname": "ContractualObligation",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CreditFacilityAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of credit facility. Credit facilities provide capital to borrowers without the need to structure a loan for each borrowing.",
        "label": "Credit Facility [Axis]",
        "terseLabel": "Credit Facility [Axis]"
       }
      }
     },
     "localname": "CreditFacilityAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails",
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CreditFacilityDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Type of credit facility. Credit facilities provide capital to borrowers without the need to structure a loan for each borrowing.",
        "label": "Credit Facility [Domain]",
        "terseLabel": "Credit Facility [Domain]"
       }
      }
     },
     "localname": "CreditFacilityDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails",
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DebtDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Debt Disclosure [Abstract]",
        "terseLabel": "Debt Disclosure [Abstract]"
       }
      }
     },
     "localname": "DebtDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtDisclosureTextBlock": {
     "auth_ref": [
      "r130"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.",
        "label": "Debt Disclosure [Text Block]",
        "terseLabel": "Loan and Security Agreements"
       }
      }
     },
     "localname": "DebtDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreements"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DebtInstrumentAxis": {
     "auth_ref": [
      "r8",
      "r9",
      "r10",
      "r255",
      "r256",
      "r261"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of debt instrument, including, but not limited to, draws against credit facilities.",
        "label": "Debt Instrument [Axis]",
        "terseLabel": "Debt Instrument [Axis]"
       }
      }
     },
     "localname": "DebtInstrumentAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtInstrumentBasisSpreadOnVariableRate1": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Percentage points added to the reference rate to compute the variable rate on the debt instrument.",
        "label": "Debt Instrument, Basis Spread on Variable Rate",
        "terseLabel": "Loan and security agreement, basis spread on interest rate"
       }
      }
     },
     "localname": "DebtInstrumentBasisSpreadOnVariableRate1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_DebtInstrumentInterestRateStatedPercentage": {
     "auth_ref": [
      "r29"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Contractual interest rate for funds borrowed, under the debt agreement.",
        "label": "Debt Instrument, Interest Rate, Stated Percentage",
        "terseLabel": "Loan and security agreement, interest rate"
       }
      }
     },
     "localname": "DebtInstrumentInterestRateStatedPercentage",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_DebtInstrumentNameDomain": {
     "auth_ref": [
      "r30"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The name for the particular debt instrument or borrowing that distinguishes it from other debt instruments or borrowings, including draws against credit facilities.",
        "label": "Debt Instrument, Name [Domain]",
        "terseLabel": "Debt Instrument, Name [Domain]"
       }
      }
     },
     "localname": "DebtInstrumentNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet": {
     "auth_ref": [
      "r127",
      "r211"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of unamortized debt discount (premium) and debt issuance costs.",
        "label": "Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net",
        "negatedLabel": "Less amounts representing interest and discount"
       }
      }
     },
     "localname": "DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredFinanceCostsGross": {
     "auth_ref": [
      "r211"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.",
        "label": "Debt Issuance Costs, Gross",
        "terseLabel": "Fees incurred to establish facility"
       }
      }
     },
     "localname": "DeferredFinanceCostsGross",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredFinanceCostsNet": {
     "auth_ref": [
      "r23",
      "r211"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.",
        "label": "Debt Issuance Costs, Net",
        "terseLabel": "Deferred issuance costs, net"
       }
      }
     },
     "localname": "DeferredFinanceCostsNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredRentCreditNoncurrent": {
     "auth_ref": [
      "r33",
      "r212"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 4.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "For a classified balance sheet, the cumulative difference between the rental income or payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense, by the lessor or lessee, respectively, more than one year after the balance sheet date.",
        "label": "Deferred Rent Credit, Noncurrent",
        "terseLabel": "Deferred rent, net of current portion"
       }
      }
     },
     "localname": "DeferredRentCreditNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Depreciation": {
     "auth_ref": [
      "r67",
      "r117"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 3.0,
       "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",
        "verboseLabel": "Depreciation expense"
       }
      }
     },
     "localname": "Depreciation",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows",
      "http://evelobio.com/role/PropertyandEquipmentNetNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock": {
     "auth_ref": [
      "r174"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensation"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Share-based Payment Arrangement [Abstract]",
        "terseLabel": "Disclosure of Compensation Related Costs, Share-based Payments [Abstract]"
       }
      }
     },
     "localname": "DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DueToRelatedPartiesCurrentAndNoncurrent": {
     "auth_ref": [
      "r83",
      "r228",
      "r258",
      "r269"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Carrying amount as of the balance sheet date of obligations due all related parties.",
        "label": "Due to Related Parties",
        "terseLabel": "Amounts due to related party"
       }
      }
     },
     "localname": "DueToRelatedPartiesCurrentAndNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EarningsPerShareAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Earnings Per Share [Abstract]",
        "terseLabel": "Earnings Per Share [Abstract]"
       }
      }
     },
     "localname": "EarningsPerShareAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_EarningsPerShareBasicAndDiluted": {
     "auth_ref": [
      "r89"
     ],
     "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 attributable to common stockholders, basic and diluted (in dollars per share)"
       }
      }
     },
     "localname": "EarningsPerShareBasicAndDiluted",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_EarningsPerShareTextBlock": {
     "auth_ref": [
      "r92"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for earnings per share.",
        "label": "Earnings Per Share [Text Block]",
        "terseLabel": "Net Loss Per Share"
       }
      }
     },
     "localname": "EarningsPerShareTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShare"
     ],
     "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": "Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockbasedCompensationExpenseDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1": {
     "auth_ref": [
      "r168"
     ],
     "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": "Compensation cost not yet recognized, period for recognition"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions": {
     "auth_ref": [
      "r168"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cost to be recognized for option under share-based payment arrangement.",
        "label": "Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount",
        "terseLabel": "Unrecognized compensation expense"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EmployeeStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "An Employee Stock Purchase Plan is a tax-efficient means by which employees of a corporation can purchase the corporation's stock.",
        "label": "Employee Stock [Member]",
        "terseLabel": "Common stock offering from ESPP"
       }
      }
     },
     "localname": "EmployeeStockMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EmployeeStockOptionMember": {
     "auth_ref": [
      "r165"
     ],
     "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 to purchase common stock",
        "verboseLabel": "Stock Options"
       }
      }
     },
     "localname": "EmployeeStockOptionMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails",
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EquipmentMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tangible personal property used to produce goods and services.",
        "label": "Equipment [Member]",
        "terseLabel": "Lab equipment"
       }
      }
     },
     "localname": "EquipmentMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Equity [Abstract]"
       }
      }
     },
     "localname": "EquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_EquityComponentDomain": {
     "auth_ref": [
      "r134"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "EquityComponentDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable": {
     "auth_ref": [
      "r202",
      "r203",
      "r204",
      "r207"
     ],
     "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 Measurements, Recurring and Nonrecurring [Table]"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTableTextBlock": {
     "auth_ref": [
      "r202",
      "r203",
      "r204",
      "r206",
      "r207"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.",
        "label": "Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]",
        "terseLabel": "Summary of Financial Assets and Liabilities Measured at Fair Value"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueByFairValueHierarchyLevelAxis": {
     "auth_ref": [
      "r143",
      "r144",
      "r146",
      "r203",
      "r236"
     ],
     "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 [Axis]"
       }
      }
     },
     "localname": "FairValueByFairValueHierarchyLevelAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosuresAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Fair Value Disclosures [Abstract]",
        "terseLabel": "Fair Value Disclosures [Abstract]"
       }
      }
     },
     "localname": "FairValueDisclosuresAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosuresTextBlock": {
     "auth_ref": [
      "r205"
     ],
     "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 Measurements"
       }
      }
     },
     "localname": "FairValueDisclosuresTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurements"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueInputsLevel1Member": {
     "auth_ref": [
      "r143",
      "r144",
      "r146",
      "r203",
      "r237"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel2Member": {
     "auth_ref": [
      "r143",
      "r144",
      "r146",
      "r203",
      "r238"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel3Member": {
     "auth_ref": [
      "r143",
      "r144",
      "r146",
      "r203",
      "r239"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.",
        "label": "Fair Value, Inputs, Level 3 [Member]",
        "terseLabel": "(Level 3)"
       }
      }
     },
     "localname": "FairValueInputsLevel3Member",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementsFairValueHierarchyDomain": {
     "auth_ref": [],
     "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 [Domain]"
       }
      }
     },
     "localname": "FairValueMeasurementsFairValueHierarchyDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueOfFinancialInstrumentsPolicy": {
     "auth_ref": [
      "r76",
      "r208",
      "r209"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for determining the fair value of financial instruments.",
        "label": "Fair Value of Financial Instruments, Policy [Policy Text Block]",
        "terseLabel": "Fair Value of Financial Instruments"
       }
      }
     },
     "localname": "FairValueOfFinancialInstrumentsPolicy",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FinancialInstrumentAxis": {
     "auth_ref": [
      "r108",
      "r109",
      "r110",
      "r111",
      "r112",
      "r113",
      "r114",
      "r115",
      "r116"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of financial instrument.",
        "label": "Financial Instrument [Axis]",
        "terseLabel": "Financial Instrument [Axis]"
       }
      }
     },
     "localname": "FinancialInstrumentAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails",
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FurnitureAndFixturesMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Equipment commonly used in offices and stores that have no permanent connection to the structure of a building or utilities. Examples include, but are not limited to, desks, chairs, tables, and bookcases.",
        "label": "Furniture and Fixtures [Member]",
        "terseLabel": "Furniture and fixtures"
       }
      }
     },
     "localname": "FurnitureAndFixturesMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_GainLossOnSaleOfPropertyPlantEquipment": {
     "auth_ref": [
      "r67"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 7.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.",
        "label": "Gain (Loss) on Disposition of Property Plant Equipment",
        "negatedTerseLabel": "Gain on sale of fixed assets, net"
       }
      }
     },
     "localname": "GainLossOnSaleOfPropertyPlantEquipment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GeneralAndAdministrativeExpense": {
     "auth_ref": [
      "r49"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 2.0,
       "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"
       }
      }
     },
     "localname": "GeneralAndAdministrativeExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GeneralAndAdministrativeExpenseMember": {
     "auth_ref": [
      "r48"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Primary financial statement caption encompassing general and administrative expense.",
        "label": "General and Administrative Expense [Member]",
        "terseLabel": "General and administrative"
       }
      }
     },
     "localname": "GeneralAndAdministrativeExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockbasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments": {
     "auth_ref": [
      "r82"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 1.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.",
        "label": "Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest",
        "totalLabel": "Loss before income taxes"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeStatementAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Income Statement [Abstract]",
        "terseLabel": "Income Statement [Abstract]"
       }
      }
     },
     "localname": "IncomeStatementAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementLocationAxis": {
     "auth_ref": [
      "r121"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by location in the income statement.",
        "label": "Income Statement Location [Axis]",
        "terseLabel": "Income Statement Location [Axis]"
       }
      }
     },
     "localname": "IncomeStatementLocationAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockbasedCompensationExpenseDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementLocationDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Location in the income statement.",
        "label": "Income Statement Location [Domain]",
        "terseLabel": "Income Statement Location [Domain]"
       }
      }
     },
     "localname": "IncomeStatementLocationDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockbasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncomeTaxDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Income Tax Disclosure [Abstract]",
        "terseLabel": "Income Tax Disclosure [Abstract]"
       }
      }
     },
     "localname": "IncomeTaxDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeTaxDisclosureTextBlock": {
     "auth_ref": [
      "r185"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.",
        "label": "Income Tax Disclosure [Text Block]",
        "terseLabel": "Income Taxes"
       }
      }
     },
     "localname": "IncomeTaxDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/IncomeTaxes"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_IncomeTaxExpenseBenefit": {
     "auth_ref": [
      "r77",
      "r102",
      "r183"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 2.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.",
        "label": "Income Tax Expense (Benefit)",
        "negatedLabel": "Income tax expense",
        "terseLabel": "Provision for income taxes"
       }
      }
     },
     "localname": "IncomeTaxExpenseBenefit",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss",
      "http://evelobio.com/role/IncomeTaxesDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeTaxPolicyTextBlock": {
     "auth_ref": [
      "r46",
      "r76",
      "r178",
      "r179",
      "r180",
      "r181",
      "r182",
      "r184",
      "r273"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.",
        "label": "Income Tax, Policy [Policy Text Block]",
        "terseLabel": "Income Taxes"
       }
      }
     },
     "localname": "IncomeTaxPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/IncomeTaxesPolicies",
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_IncomeTaxesPaidNet": {
     "auth_ref": [
      "r71"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.",
        "label": "Income Taxes Paid, Net",
        "terseLabel": "Cash paid for taxes"
       }
      }
     },
     "localname": "IncomeTaxesPaidNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInAccountsPayable": {
     "auth_ref": [
      "r66"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "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"
       }
      }
     },
     "localname": "IncreaseDecreaseInAccountsPayable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities": {
     "auth_ref": [
      "r66"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 10.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) in accrued expenses, and obligations classified as other.",
        "label": "Increase (Decrease) in Accrued Liabilities and Other Operating Liabilities",
        "terseLabel": "Accrued expenses and other current liabilities"
       }
      }
     },
     "localname": "IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncreaseDecreaseInOtherOperatingLiabilities": {
     "auth_ref": [
      "r66"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 12.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of increase (decrease) in operating liabilities classified as other.",
        "label": "Increase (Decrease) in Other Operating Liabilities",
        "terseLabel": "Other liabilities"
       }
      }
     },
     "localname": "IncreaseDecreaseInOtherOperatingLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets": {
     "auth_ref": [
      "r66"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 8.0,
       "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"
       }
      }
     },
     "localname": "IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInStockholdersEquityRollForward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.",
        "label": "Increase (Decrease) in Stockholders' Equity [Roll Forward]",
        "terseLabel": "Increase (Decrease) in Stockholders' Equity [Roll Forward]"
       }
      }
     },
     "localname": "IncreaseDecreaseInStockholdersEquityRollForward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_InterestExpenseDebt": {
     "auth_ref": [
      "r52",
      "r129"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of the cost of borrowed funds accounted for as interest expense for debt.",
        "label": "Interest Expense, Debt",
        "terseLabel": "Interest expense"
       }
      }
     },
     "localname": "InterestExpenseDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestPaidNet": {
     "auth_ref": [
      "r61",
      "r64",
      "r71"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash paid for interest, excluding capitalized interest, classified as operating activity. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.",
        "label": "Interest Paid, Excluding Capitalized Interest, Operating Activities",
        "terseLabel": "Cash paid for interest"
       }
      }
     },
     "localname": "InterestPaidNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InvestmentIncomeNet": {
     "auth_ref": [
      "r50",
      "r52",
      "r53"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 1.0,
       "parentTag": "us-gaap_NonoperatingIncomeExpense",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after accretion (amortization) of discount (premium), and investment expense, of interest income and dividend income on nonoperating securities.",
        "label": "Investment Income, Net",
        "terseLabel": "Interest (expense) income, net"
       }
      }
     },
     "localname": "InvestmentIncomeNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LeaseCostAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Lease, Cost [Abstract]",
        "terseLabel": "Other information:"
       }
      }
     },
     "localname": "LeaseCostAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LeaseholdImprovementsMember": {
     "auth_ref": [
      "r118"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LeasesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Leases [Abstract]"
       }
      }
     },
     "localname": "LeasesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock": {
     "auth_ref": [
      "r222"
     ],
     "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 Minimum Aggregate Future Lease Commitments"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityMaturityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails_1": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments for operating lease.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due",
        "totalLabel": "Total lease payments"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails": {
       "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 payments for operating lease, due after fifth fiscal year following latest fiscal year.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due after Year Five",
        "terseLabel": "Thereafter"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails": {
       "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 payments for operating lease, due in fifth fiscal year following latest fiscal year.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due Year Five",
        "terseLabel": "2024"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueYearFive",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails": {
       "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 payments for operating lease, due in fourth fiscal year following latest fiscal year.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due Year Four",
        "terseLabel": "2023"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueYearFour",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails": {
       "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 payments for operating lease, due in third fiscal year following latest fiscal year.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due Year Three",
        "terseLabel": "2022"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueYearThree",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails": {
       "order": 6.0,
       "parentTag": "us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lessee's undiscounted obligation for lease payments for operating lease, due in second fiscal year following latest fiscal year.",
        "label": "Lessee, Operating Lease, Liability, Payments, Due Year Two",
        "terseLabel": "2021"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsDueYearTwo",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails": {
       "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 payments for operating lease having an initial or remaining lease term in excess of one year due in remainder of fiscal year following latest fiscal year.",
        "label": "Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year",
        "terseLabel": "2020 (excluding six month ended June 30. 2020)"
       }
      }
     },
     "localname": "LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount": {
     "auth_ref": [
      "r222"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails_1": {
       "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 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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LesseeOperatingLeasesTextBlock": {
     "auth_ref": [
      "r224"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for operating leases of lessee. Includes, but is not limited to, description of operating lease and maturity analysis of operating lease liability.",
        "label": "Lessee, Operating Leases [Text Block]",
        "terseLabel": "Leases"
       }
      }
     },
     "localname": "LesseeOperatingLeasesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/Leases"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_LessorOperatingLeasePaymentsToBeReceived": {
     "auth_ref": [
      "r225"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of lease payments to be received by lessor for operating lease.",
        "label": "Lessor, Operating Lease, Payments to be Received",
        "verboseLabel": "Rent due from sublease agreement"
       }
      }
     },
     "localname": "LessorOperatingLeasePaymentsToBeReceived",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Liabilities": {
     "auth_ref": [
      "r26"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesAndStockholdersEquity": {
     "auth_ref": [
      "r17",
      "r257",
      "r266"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LiabilitiesCurrent": {
     "auth_ref": [
      "r28"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 1.0,
       "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LiabilitiesNoncurrentAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Liabilities, Noncurrent [Abstract]",
        "terseLabel": "Noncurrent liabilities:"
       }
      }
     },
     "localname": "LiabilitiesNoncurrentAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LineOfCreditFacilityLineItems": {
     "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": "Line of Credit Facility [Line Items]",
        "terseLabel": "Line of Credit Facility [Line Items]"
       }
      }
     },
     "localname": "LineOfCreditFacilityLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails",
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity": {
     "auth_ref": [
      "r25"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.",
        "label": "Line of Credit Facility, Maximum Borrowing Capacity",
        "terseLabel": "Aggregate principal amount"
       }
      }
     },
     "localname": "LineOfCreditFacilityMaximumBorrowingCapacity",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LineOfCreditFacilityTable": {
     "auth_ref": [
      "r25",
      "r81"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A table or schedule providing information pertaining to short-term or long-term contractual arrangements with lenders, including letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line.",
        "label": "Line of Credit Facility [Table]",
        "terseLabel": "Line of Credit Facility [Table]"
       }
      }
     },
     "localname": "LineOfCreditFacilityTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails",
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LineOfCreditMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A contractual arrangement with a lender under which borrowings can be made up to a specific amount at any point in time, and under which borrowings outstanding may be either short-term or long-term, depending upon the particulars.",
        "label": "Line of Credit [Member]",
        "terseLabel": "Line of Credit"
       }
      }
     },
     "localname": "LineOfCreditMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails",
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_LongTermDebt": {
     "auth_ref": [
      "r10",
      "r128",
      "r256",
      "r263"
     ],
     "calculation": {
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.",
        "label": "Long-term Debt",
        "totalLabel": "Total minimum payments"
       }
      }
     },
     "localname": "LongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths": {
     "auth_ref": [
      "r84"
     ],
     "calculation": {
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails": {
       "order": 1.0,
       "parentTag": "us-gaap_LongTermDebt",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Long-term Debt, Maturities, Repayments of Principal in Next Rolling Twelve Months",
        "terseLabel": "2021"
       }
      }
     },
     "localname": "LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearFour": {
     "auth_ref": [
      "r84"
     ],
     "calculation": {
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails": {
       "order": 4.0,
       "parentTag": "us-gaap_LongTermDebt",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Long-term Debt, Maturities, Repayments of Principal in Rolling Year Four",
        "terseLabel": "2024"
       }
      }
     },
     "localname": "LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearFour",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearThree": {
     "auth_ref": [
      "r84"
     ],
     "calculation": {
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails": {
       "order": 3.0,
       "parentTag": "us-gaap_LongTermDebt",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Long-term Debt, Maturities, Repayments of Principal in Rolling Year Three",
        "terseLabel": "2023"
       }
      }
     },
     "localname": "LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearThree",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearTwo": {
     "auth_ref": [
      "r84"
     ],
     "calculation": {
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_LongTermDebt",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.",
        "label": "Long-term Debt, Maturities, Repayments of Principal in Rolling Year Two",
        "terseLabel": "2022"
       }
      }
     },
     "localname": "LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearTwo",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongTermDebtNoncurrent": {
     "auth_ref": [
      "r30"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.",
        "label": "Long-term Debt, Excluding Current Maturities",
        "terseLabel": "Long-term debt",
        "verboseLabel": "Long-term debt"
       }
      }
     },
     "localname": "LongTermDebtNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets",
      "http://evelobio.com/role/LoanandSecurityAgreementsScheduleofMinimumAggregateFutureLoanPaymentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_MoneyMarketFundsAtCarryingValue": {
     "auth_ref": [],
     "calculation": {
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_CashAndCashEquivalentsAtCarryingValue",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.",
        "label": "Money Market Funds, at Carrying Value",
        "terseLabel": "Money market funds"
       }
      }
     },
     "localname": "MoneyMarketFundsAtCarryingValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_MoneyMarketFundsMember": {
     "auth_ref": [
      "r143"
     ],
     "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 included within cash and cash equivalents"
       }
      }
     },
     "localname": "MoneyMarketFundsMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivities": {
     "auth_ref": [
      "r63"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 3.0,
       "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 financing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided by (Used in) Financing Activities [Abstract]",
        "terseLabel": "Financing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivities": {
     "auth_ref": [
      "r63"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 2.0,
       "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided by (Used in) Investing Activities [Abstract]",
        "terseLabel": "Investing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivities": {
     "auth_ref": [
      "r63",
      "r65",
      "r68"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 1.0,
       "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 used in operating activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Net Cash Provided by (Used in) Operating Activities [Abstract]",
        "terseLabel": "Operating activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetIncomeLoss": {
     "auth_ref": [
      "r41",
      "r43",
      "r47",
      "r68",
      "r91",
      "r260",
      "r270"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 1.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      }
     },
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss",
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems": {
     "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": "New Accounting Pronouncements or Change in Accounting Principle [Line Items]",
        "terseLabel": "New Accounting Pronouncements or Change in Accounting Principle [Line Items]"
       }
      }
     },
     "localname": "NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable": {
     "auth_ref": [
      "r86",
      "r87"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Summarization of the changes in an accounting principle or a new accounting pronouncement, including the line items affected by the change and the financial effects of the change on those particular line items.",
        "label": "New Accounting Pronouncements or Change in Accounting Principle [Table]",
        "terseLabel": "New Accounting Pronouncements or Change in Accounting Principle [Table]"
       }
      }
     },
     "localname": "NewAccountingPronouncementsOrChangeInAccountingPrincipleTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "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 Pronouncements"
       }
      }
     },
     "localname": "NewAccountingPronouncementsPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_NoncashInvestingAndFinancingItemsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Noncash Investing and Financing Items [Abstract]",
        "terseLabel": "Noncash investing and financing activities"
       }
      }
     },
     "localname": "NoncashInvestingAndFinancingItemsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NonoperatingIncomeExpense": {
     "auth_ref": [
      "r51"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 1.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments",
       "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)",
        "totalLabel": "Other (expense) income, net"
       }
      }
     },
     "localname": "NonoperatingIncomeExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NumberOfOperatingSegments": {
     "auth_ref": [],
     "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 segments"
       }
      }
     },
     "localname": "NumberOfOperatingSegments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OperatingExpenses": {
     "auth_ref": [],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OperatingIncomeLoss": {
     "auth_ref": [],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 2.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments",
       "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"
       }
      }
     },
     "localname": "OperatingIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseExpense": {
     "auth_ref": [
      "r216"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of operating lease expense. Excludes sublease income.",
        "label": "Operating Lease, Expense",
        "terseLabel": "Rent expense"
       }
      }
     },
     "localname": "OperatingLeaseExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLeaseIncomeLeasePayments": {
     "auth_ref": [
      "r93",
      "r226"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of operating lease income from lease payments paid and payable to lessor. Excludes variable lease payments not included in measurement of lease receivable.",
        "label": "Operating Lease, Lease Income, Lease Payments",
        "terseLabel": "Offset to rent expense from sublease agreement",
        "verboseLabel": "Minimum rental payments received"
       }
      }
     },
     "localname": "OperatingLeaseLeaseIncomeLeasePayments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesNarrativeDetails",
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Lessee, Operating Lease, Liability, Payment, Due [Abstract]",
        "terseLabel": "Lessee, Operating Lease, Liability, Payment, Due [Abstract]"
       }
      }
     },
     "localname": "OperatingLeaseLiabilitiesPaymentsDueAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OperatingLeaseLiability": {
     "auth_ref": [
      "r215"
     ],
     "calculation": {
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails_1": {
       "order": 2.0,
       "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 operating lease liabilities",
        "verboseLabel": "Operating lease liability"
       }
      }
     },
     "localname": "OperatingLeaseLiability",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails",
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLiabilityCurrent": {
     "auth_ref": [
      "r215"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 3.0,
       "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": "Operating lease liability, current portion"
       }
      }
     },
     "localname": "OperatingLeaseLiabilityCurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseLiabilityNoncurrent": {
     "auth_ref": [
      "r215"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 3.0,
       "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": "Operating lease liability, net of current portion"
       }
      }
     },
     "localname": "OperatingLeaseLiabilityNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeasePayments": {
     "auth_ref": [
      "r217",
      "r219"
     ],
     "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": "Operating cash flows used for operating leases"
       }
      }
     },
     "localname": "OperatingLeasePayments",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseRightOfUseAsset": {
     "auth_ref": [
      "r214"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "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",
        "terseLabel": "Right of use asset - operating lease",
        "verboseLabel": "Operating lease right-of-use assets"
       }
      }
     },
     "localname": "OperatingLeaseRightOfUseAsset",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets",
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent": {
     "auth_ref": [
      "r221",
      "r223"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1": {
     "auth_ref": [
      "r220",
      "r223"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesScheduleofMinimumAggregateFutureLeaseCommitmentsDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Organization, Consolidation and Presentation of Financial Statements [Abstract]",
        "terseLabel": "Organization, Consolidation and Presentation of Financial Statements [Abstract]"
       }
      }
     },
     "localname": "OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock": {
     "auth_ref": [
      "r85",
      "r88",
      "r101",
      "r201"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for the general note to the financial statements for the reporting entity which may include, descriptions of the basis of presentation, business description, significant accounting policies, consolidations, reclassifications, new pronouncements not yet adopted and changes in accounting principles.",
        "label": "Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block]",
        "terseLabel": "Organization"
       }
      }
     },
     "localname": "OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/Organization"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_OtherAssetsNoncurrent": {
     "auth_ref": [
      "r23"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "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 assets"
       }
      }
     },
     "localname": "OtherAssetsNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent": {
     "auth_ref": [
      "r190",
      "r191",
      "r195"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 2.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss.",
        "label": "Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent",
        "terseLabel": "Unrealized gain (loss) on investments, net of tax of $0",
        "verboseLabel": "Unrealized gain on investments"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss",
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent": {
     "auth_ref": [
      "r190",
      "r191",
      "r195"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss.",
        "label": "Other Comprehensive Income (Loss), Available-for-sale Securities, Tax, Portion Attributable to Parent",
        "terseLabel": "Tax portion of unrealized loss on investments"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeAvailableforsaleSecuritiesTaxPortionAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss",
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLossParenthetical"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]",
        "terseLabel": "Other comprehensive loss:"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OtherIncomeAndExpensesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Other Income and Expenses [Abstract]",
        "terseLabel": "Other (expense) income:"
       }
      }
     },
     "localname": "OtherIncomeAndExpensesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OtherLiabilitiesCurrent": {
     "auth_ref": [
      "r3",
      "r4",
      "r27"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 4.0,
       "parentTag": "us-gaap_LiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of liabilities classified as other, due within one year or the normal operating cycle, if longer.",
        "label": "Other Liabilities, Current",
        "terseLabel": "Other current liabilities"
       }
      }
     },
     "localname": "OtherLiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherLiabilitiesNoncurrent": {
     "auth_ref": [
      "r31"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 5.0,
       "parentTag": "us-gaap_Liabilities",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.",
        "label": "Other Liabilities, Noncurrent",
        "terseLabel": "Other noncurrent liabilities"
       }
      }
     },
     "localname": "OtherLiabilitiesNoncurrent",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherNonoperatingIncomeExpense": {
     "auth_ref": [
      "r53"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 2.0,
       "parentTag": "us-gaap_NonoperatingIncomeExpense",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of income (expense) related to nonoperating activities, classified as other.",
        "label": "Other Nonoperating Income (Expense)",
        "terseLabel": "Other income, net"
       }
      }
     },
     "localname": "OtherNonoperatingIncomeExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OverAllotmentOptionMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Right given to the underwriter to sell additional shares over the initial allotment.",
        "label": "Over-Allotment Option [Member]",
        "terseLabel": "Over-Allotment Option"
       }
      }
     },
     "localname": "OverAllotmentOptionMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PaymentsOfStockIssuanceCosts": {
     "auth_ref": [
      "r60"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 1.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "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",
        "negatedTerseLabel": "Payment of deferred offering costs"
       }
      }
     },
     "localname": "PaymentsOfStockIssuanceCosts",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsToAcquirePropertyPlantAndEquipment": {
     "auth_ref": [
      "r57"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 2.0,
       "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": "Purchases of property and equipment"
       }
      }
     },
     "localname": "PaymentsToAcquirePropertyPlantAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PlanNameAxis": {
     "auth_ref": [
      "r150",
      "r169"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by plan name for share-based payment arrangement.",
        "label": "Plan Name [Axis]",
        "terseLabel": "Plan Name [Axis]"
       }
      }
     },
     "localname": "PlanNameAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "PlanNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PreferredStockMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Preferred shares may provide a preferential dividend to the dividend on common stock and may take precedence over common stock in the event of a liquidation. Preferred shares typically represent an ownership interest in the company.",
        "label": "Preferred Stock [Member]",
        "terseLabel": "Preferred Stock"
       }
      }
     },
     "localname": "PreferredStockMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PreferredStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r11"
     ],
     "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 (in dollars per share)"
       }
      }
     },
     "localname": "PreferredStockParOrStatedValuePerShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_PreferredStockSharesAuthorized": {
     "auth_ref": [
      "r11"
     ],
     "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",
        "terseLabel": "Preferred stock, authorized (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesIssued": {
     "auth_ref": [
      "r11"
     ],
     "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, issued (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesOutstanding": {
     "auth_ref": [
      "r11"
     ],
     "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",
        "terseLabel": "Preferred stock, outstanding (in shares)"
       }
      }
     },
     "localname": "PreferredStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockValue": {
     "auth_ref": [
      "r11"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "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 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",
        "terseLabel": "Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued or outstanding at June 30, 2020 and December\u00a031, 2019, respectively"
       }
      }
     },
     "localname": "PreferredStockValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PrepaidExpenseAndOtherAssetsCurrent": {
     "auth_ref": [
      "r1",
      "r18",
      "r19"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PrimeRateMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Interest rate charged by financial institutions to their most creditworthy borrowers.",
        "label": "Prime Rate [Member]",
        "terseLabel": "Prime Plus"
       }
      }
     },
     "localname": "PrimeRateMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ProceedsFromIssuanceOfCommonStock": {
     "auth_ref": [
      "r58"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 2.0,
       "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": "Gross proceeds from issuance of common stock",
        "verboseLabel": "Proceeds from issuance of common stock, net of issuance cost"
       }
      }
     },
     "localname": "ProceedsFromIssuanceOfCommonStock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows",
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails",
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromIssuanceOfLongTermDebt": {
     "auth_ref": [
      "r59"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.",
        "label": "Proceeds from Issuance of Long-term Debt",
        "verboseLabel": "Proceeds from Issuance of Long-term Debt"
       }
      }
     },
     "localname": "ProceedsFromIssuanceOfLongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions": {
     "auth_ref": [
      "r58",
      "r170"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 3.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of cash inflow from issuance of shares under share-based payment arrangement. Includes, but is not limited to, option exercised.",
        "label": "Proceeds, Issuance of Shares, Share-based Payment Arrangement, Including Option Exercised",
        "terseLabel": "Proceeds from the exercise of stock options"
       }
      }
     },
     "localname": "ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities": {
     "auth_ref": [
      "r54",
      "r55",
      "r107"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 1.0,
       "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 sales and maturities of investments"
       }
      }
     },
     "localname": "ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleOfProductiveAssets": {
     "auth_ref": [
      "r56"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 3.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The cash inflow from the sale of property, plant and equipment (capital expenditures), software, and other intangible assets.",
        "label": "Proceeds from Sale of Productive Assets",
        "terseLabel": "Proceeds from sale of fixed assets"
       }
      }
     },
     "localname": "ProceedsFromSaleOfProductiveAssets",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProfitLoss": {
     "auth_ref": [
      "r41",
      "r43",
      "r62",
      "r103",
      "r104",
      "r190",
      "r193",
      "r194",
      "r197",
      "r198"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "order": 1.0,
       "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"
       }
      }
     },
     "localname": "ProfitLoss",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Property, Plant and Equipment [Abstract]",
        "terseLabel": "Property, Plant and Equipment [Abstract]"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentByTypeAxis": {
     "auth_ref": [
      "r22",
      "r120"
     ],
     "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": "Property, Plant and Equipment, Type [Axis]",
        "terseLabel": "Property, Plant and Equipment, Type [Axis]"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentByTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock": {
     "auth_ref": [
      "r122"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The entire disclosure for long-lived, physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, accounting policies and methodology, roll forwards, depreciation, depletion and amortization expense, including composite depreciation, accumulated depreciation, depletion and amortization expense, useful lives and method used, income statement disclosures, assets held for sale and public utility disclosures.",
        "label": "Property, Plant and Equipment Disclosure [Text Block]",
        "terseLabel": "Property and Equipment, Net"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNet"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentGross": {
     "auth_ref": [
      "r21",
      "r118"
     ],
     "calculation": {
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails": {
       "order": 1.0,
       "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",
        "terseLabel": "Property and equipment"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentGross",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentGrossAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Property, Plant and Equipment, Gross [Abstract]",
        "terseLabel": "Property and equipment:"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentGrossAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentNet": {
     "auth_ref": [
      "r6",
      "r7",
      "r120",
      "r267"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 2.0,
       "parentTag": "us-gaap_Assets",
       "weight": 1.0
      },
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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",
        "terseLabel": "Property and equipment, net",
        "totalLabel": "Property and equipment, net"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentNet",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets",
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentTextBlock": {
     "auth_ref": [
      "r6",
      "r120"
     ],
     "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": "Summary of Property and Equipment"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentTypeDomain": {
     "auth_ref": [
      "r6",
      "r118"
     ],
     "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": "Property, Plant and Equipment, Type [Domain]",
        "terseLabel": "Property, Plant and Equipment, Type [Domain]"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RelatedPartyDomain": {
     "auth_ref": [
      "r234"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "RelatedPartyDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RelatedPartyTransactionAmountsOfTransaction": {
     "auth_ref": [
      "r227",
      "r230",
      "r231"
     ],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of transactions with related party during the financial reporting period.",
        "label": "Related Party Transaction, Amounts of Transaction",
        "terseLabel": "Payment to related party"
       }
      }
     },
     "localname": "RelatedPartyTransactionAmountsOfTransaction",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RelatedPartyTransactionAxis": {
     "auth_ref": [
      "r145",
      "r229",
      "r230"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of related party transaction.",
        "label": "Related Party Transaction [Axis]",
        "terseLabel": "Related Party Transaction [Axis]"
       }
      }
     },
     "localname": "RelatedPartyTransactionAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RelatedPartyTransactionDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Transaction between related party.",
        "label": "Related Party Transaction [Domain]",
        "terseLabel": "Related Party Transaction [Domain]"
       }
      }
     },
     "localname": "RelatedPartyTransactionDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RelatedPartyTransactionsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Related Party Transactions [Abstract]",
        "terseLabel": "Related Party Transactions [Abstract]"
       }
      }
     },
     "localname": "RelatedPartyTransactionsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_RelatedPartyTransactionsByRelatedPartyAxis": {
     "auth_ref": [
      "r145",
      "r229",
      "r230",
      "r241",
      "r242",
      "r243",
      "r244",
      "r245",
      "r246",
      "r247",
      "r248",
      "r249",
      "r250",
      "r251",
      "r252"
     ],
     "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 [Axis]"
       }
      }
     },
     "localname": "RelatedPartyTransactionsByRelatedPartyAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RelatedPartyTransactionsDisclosureTextBlock": {
     "auth_ref": [
      "r234"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactions"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ResearchAndDevelopmentAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Research and Development [Abstract]",
        "terseLabel": "Research and Development [Abstract]"
       }
      }
     },
     "localname": "ResearchAndDevelopmentAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems": {
     "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": "Research and Development Arrangement, Contract to Perform for Others [Line Items]",
        "terseLabel": "Research and Development Arrangement, Contract to Perform for Others [Line Items]"
       }
      }
     },
     "localname": "ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ResearchAndDevelopmentExpense": {
     "auth_ref": [
      "r175",
      "r274"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss": {
       "order": 1.0,
       "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"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpense",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "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"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockbasedCompensationExpenseDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ResearchAndDevelopmentExpensePolicy": {
     "auth_ref": [
      "r76",
      "r175"
     ],
     "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 Costs"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpensePolicy",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_RestrictedCash": {
     "auth_ref": [
      "r75",
      "r253",
      "r264"
     ],
     "calculation": {
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails": {
       "order": 2.0,
       "parentTag": "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents",
       "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"
       }
      }
     },
     "localname": "RestrictedCash",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails",
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesReconciliationofCashCashEquivalentsandRestrictedCashDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RetainedEarningsAccumulatedDeficit": {
     "auth_ref": [
      "r14",
      "r141",
      "r265"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "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)",
        "negatedTerseLabel": "Accumulated deficit",
        "terseLabel": "Accumulated deficit"
       }
      }
     },
     "localname": "RetainedEarningsAccumulatedDeficit",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets",
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RetainedEarningsMember": {
     "auth_ref": [],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SaleOfStockConsiderationReceivedOnTransaction": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Cash received on stock transaction after deduction of issuance costs.",
        "label": "Sale of Stock, Consideration Received on Transaction",
        "terseLabel": "Net proceeds from issuance of common stock"
       }
      }
     },
     "localname": "SaleOfStockConsiderationReceivedOnTransaction",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails",
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "SaleOfStockNameOfTransactionDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails",
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.",
        "label": "Sale of Stock, Number of Shares Issued in Transaction",
        "terseLabel": "Number of shares sold in public offering (in shares)"
       }
      }
     },
     "localname": "SaleOfStockNumberOfSharesIssuedInTransaction",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails",
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_SaleOfStockPricePerShare": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.",
        "label": "Sale of Stock, Price Per Share",
        "terseLabel": "Price of shares sold in public offering (in dollars per share)"
       }
      }
     },
     "localname": "SaleOfStockPricePerShare",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails",
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable": {
     "auth_ref": [
      "r90"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedWeightedAverageSharesOutstandingDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock": {
     "auth_ref": [
      "r90"
     ],
     "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 Excluded from Computation of Diluted Weighted-Average Shares Outstanding"
       }
      }
     },
     "localname": "ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/NetLossPerShareTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the components of cash and cash equivalents.",
        "label": "Schedule of Cash and Cash Equivalents [Table Text Block]",
        "terseLabel": "Reconciliation of Cash, Cash Equivalents and Restricted Cash"
       }
      }
     },
     "localname": "ScheduleOfCashAndCashEquivalentsTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable": {
     "auth_ref": [
      "r149",
      "r166",
      "r171"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockbasedCompensationExpenseDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock": {
     "auth_ref": [
      "r149",
      "r166",
      "r171"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock": {
     "auth_ref": [
      "r126"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Tabular disclosure of the combined aggregate amount of maturities and sinking fund requirements for all long-term borrowings for each of the five years following the date of the latest balance sheet date presented.",
        "label": "Schedule of Maturities of Long-term Debt [Table Text Block]",
        "terseLabel": "Schedule of Minimum Aggregate Future Loan Payments"
       }
      }
     },
     "localname": "ScheduleOfMaturitiesOfLongTermDebtTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfPropertyPlantAndEquipmentTable": {
     "auth_ref": [
      "r22",
      "r120"
     ],
     "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": "Property, Plant and Equipment [Table]"
       }
      }
     },
     "localname": "ScheduleOfPropertyPlantAndEquipmentTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable": {
     "auth_ref": [
      "r78",
      "r229",
      "r230",
      "r231",
      "r232",
      "r233"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfResearchAndDevelopmentArrangementContractToPerformForOthersTable": {
     "auth_ref": [
      "r176",
      "r177"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A schedule reflecting the terms of significant agreements under research and development arrangements accounted for as a contract to perform research and development for others (including royalty arrangements, purchase provisions, license agreements, and commitments to provide additional funding), aggregated by similar arrangements or individually if necessary to understand the effects on the financial statements.",
        "label": "Schedule of Research and Development Arrangement, Contract to Perform for Others [Table]",
        "terseLabel": "Schedule of Research and Development Arrangement, Contract to Perform for Others [Table]"
       }
      }
     },
     "localname": "ScheduleOfResearchAndDevelopmentArrangementContractToPerformForOthersTable",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable": {
     "auth_ref": [
      "r150",
      "r169"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock": {
     "auth_ref": [
      "r156",
      "r162",
      "r164"
     ],
     "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 Activity"
       }
      }
     },
     "localname": "ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfStockByClassTable": {
     "auth_ref": [
      "r34",
      "r80",
      "r131",
      "r132",
      "r133",
      "r135",
      "r136",
      "r137",
      "r138",
      "r139",
      "r140",
      "r141"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SegmentReportingPolicyPolicyTextBlock": {
     "auth_ref": [
      "r76"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ShareBasedCompensation": {
     "auth_ref": [
      "r66"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows": {
       "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"
       }
      }
     },
     "localname": "ShareBasedCompensation",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1": {
     "auth_ref": [
      "r151"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of additional shares authorized for issuance under share-based payment arrangement.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized",
        "terseLabel": "Number of additional shares authorized for issuance (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized": {
     "auth_ref": [
      "r153"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Number of shares authorized for issuance under share-based payment arrangement.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized",
        "terseLabel": "Number of shares originally authorized for issuance (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant": {
     "auth_ref": [
      "r169"
     ],
     "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",
        "terseLabel": "Number of common stock available for future grant (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber": {
     "auth_ref": [
      "r159"
     ],
     "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": "Exercisable as of period end (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice": {
     "auth_ref": [
      "r159"
     ],
     "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": "Exercisable as of period end (in dollars per share)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod": {
     "auth_ref": [
      "r161"
     ],
     "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": "Canceled (in shares)",
        "terseLabel": "Number of shares canceled (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "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 stock options granted (in shares)",
        "verboseLabel": "Granted (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/RelatedPartyTransactionsNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue": {
     "auth_ref": [
      "r163"
     ],
     "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 fair value of options granted (in dollars per share)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber": {
     "auth_ref": [
      "r158",
      "r169"
     ],
     "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": "Options outstanding, ending balance (in shares)",
        "periodStartLabel": "Options outstanding, beginning balance (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.",
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]",
        "terseLabel": "Shares"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice": {
     "auth_ref": [
      "r157"
     ],
     "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": "Options outstanding, ending balance (in dollars per share)",
        "periodStartLabel": "Options outstanding, beginning balance (in dollars per share)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]",
        "terseLabel": "Weighted- Average Exercise Price"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "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": "Percentage of outstanding shares"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod": {
     "auth_ref": [
      "r169"
     ],
     "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": "Number of shares issued for purchase (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain": {
     "auth_ref": [
      "r148",
      "r154"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Award under share-based payment arrangement.",
        "label": "Award Type [Domain]",
        "terseLabel": "Equity Award [Domain]"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "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": "Exercised (in dollars per share)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "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": "Canceled (in dollars per share)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "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": "Granted (in dollars per share)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy": {
     "auth_ref": [
      "r76",
      "r150",
      "r155"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod": {
     "auth_ref": [
      "r152"
     ],
     "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": "Options granted, maximum expiration period"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails"
     ],
     "xbrltype": "durationItemType"
    },
    "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": "Ending balance (in shares)",
        "periodStartLabel": "Beginning balance (in shares)"
       }
      }
     },
     "localname": "SharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_SignificantAccountingPoliciesTextBlock": {
     "auth_ref": [
      "r85"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_StatementEquityComponentsAxis": {
     "auth_ref": [
      "r35",
      "r134"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by component of equity.",
        "label": "Equity Components [Axis]",
        "terseLabel": "Equity Components [Axis]"
       }
      }
     },
     "localname": "StatementEquityComponentsAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfCashFlowsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement of Cash Flows [Abstract]",
        "terseLabel": "Statement of Cash Flows [Abstract]"
       }
      }
     },
     "localname": "StatementOfCashFlowsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfFinancialPositionAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement of Financial Position [Abstract]",
        "terseLabel": "Statement of Financial Position [Abstract]"
       }
      }
     },
     "localname": "StatementOfFinancialPositionAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfStockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Statement of Stockholders' Equity [Abstract]",
        "terseLabel": "Statement of Stockholders' Equity [Abstract]"
       }
      }
     },
     "localname": "StatementOfStockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementTable": {
     "auth_ref": [],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesNewIssues": {
     "auth_ref": [
      "r11",
      "r12",
      "r134",
      "r141"
     ],
     "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 in public offering, net of fees (in shares)"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesNewIssues",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross": {
     "auth_ref": [
      "r134",
      "r141"
     ],
     "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": "Vesting of restricted common stock (in shares)"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesRestrictedStockAwardGross",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised": {
     "auth_ref": [
      "r11",
      "r12",
      "r134",
      "r141",
      "r160"
     ],
     "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": "Exercised (in shares)",
        "netLabel": "Number of shares exercised (in shares)",
        "terseLabel": "Exercise of stock options (in shares)"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesStockOptionsExercised",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity",
      "http://evelobio.com/role/StockBasedCompensationNarrativeDetails",
      "http://evelobio.com/role/StockBasedCompensationSummaryofStockOptionActivityDetails"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueNewIssues": {
     "auth_ref": [
      "r11",
      "r12",
      "r134",
      "r141"
     ],
     "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": "Issuance of common stock in public offering, net of fees"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueNewIssues",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross": {
     "auth_ref": [
      "r11",
      "r12",
      "r134",
      "r141"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Aggregate value of stock related to Restricted Stock Awards issued during the period.",
        "label": "Stock Issued During Period, Value, Restricted Stock Award, Gross",
        "terseLabel": "Vesting of restricted common stock"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodValueRestrictedStockAwardGross",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised": {
     "auth_ref": [
      "r35",
      "r134",
      "r141"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquity": {
     "auth_ref": [
      "r12",
      "r15",
      "r16",
      "r106"
     ],
     "calculation": {
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets": {
       "order": 3.0,
       "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": "Ending balance",
        "periodStartLabel": "Beginning balance",
        "totalLabel": "Total stockholders\u2019 equity"
       }
      }
     },
     "localname": "StockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets",
      "http://evelobio.com/role/CondensedConsolidatedStatementsofPreferredStockandStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Stockholders' Equity Attributable to Parent [Abstract]",
        "terseLabel": "Stockholder\u2019s equity:"
       }
      }
     },
     "localname": "StockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockholdersEquityNoteDisclosureTextBlock": {
     "auth_ref": [
      "r142"
     ],
     "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\u2019 Equity"
       }
      }
     },
     "localname": "StockholdersEquityNoteDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/StockholdersEquity"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SubleaseIncome": {
     "auth_ref": [
      "r218",
      "r223"
     ],
     "crdr": "credit",
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Amount of sublease income excluding finance and operating lease expense.",
        "label": "Sublease Income",
        "terseLabel": "Sublease rent income"
       }
      }
     },
     "localname": "SubleaseIncome",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LeasesNarrativeDetails"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_SubsequentEventMember": {
     "auth_ref": [],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SubsequentEventTypeAxis": {
     "auth_ref": [
      "r235"
     ],
     "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 [Axis]"
       }
      }
     },
     "localname": "SubsequentEventTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SubsequentEventTypeDomain": {
     "auth_ref": [
      "r235"
     ],
     "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 [Domain]"
       }
      }
     },
     "localname": "SubsequentEventTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_SubsequentEventsPolicyPolicyTextBlock": {
     "auth_ref": [
      "r76"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Disclosure of accounting policy for reporting subsequent events.",
        "label": "Subsequent Events, Policy [Policy Text Block]",
        "terseLabel": "Subsequent Event Considerations"
       }
      }
     },
     "localname": "SubsequentEventsPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails"
     ],
     "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 [Axis]"
       }
      }
     },
     "localname": "SubsidiarySaleOfStockAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails",
      "http://evelobio.com/role/StockholdersEquityDetails"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/OrganizationAdditionalInformationDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SupplementalCashFlowInformationAbstract": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "label": "Supplemental Cash Flow Information [Abstract]",
        "terseLabel": "Supplemental disclosure of cash flow information"
       }
      }
     },
     "localname": "SupplementalCashFlowInformationAbstract",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain": {
     "auth_ref": [
      "r240"
     ],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Instrument or contract that imposes a contractual obligation to deliver cash or another financial instrument or to exchange other financial instruments on potentially unfavorable terms and conveys a contractual right to receive cash or another financial instrument or to exchange other financial instruments on potentially favorable terms.",
        "label": "Financial Instruments [Domain]",
        "terseLabel": "Financial Instruments [Domain]"
       }
      }
     },
     "localname": "TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/FairValueMeasurementsSummaryofFinancialAssetsandLiabilitiesMeasuredatFairValueDetails",
      "http://evelobio.com/role/InLicenseAgreementsNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_TypeOfAdoptionMember": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Adoption and early adoption of sources of change to generally accepted accounting principles (GAAP) in the United States. The FASB released the FASB Accounting Standards Codification as the authoritative source of literature effective for interim and annual periods ending after September 15, 2009. As part of the Codification process, the FASB issues Accounting Standards Updates to amend the Codification but otherwise the Accounting Standards Updates are not authoritative in their own right. All previous accounting standards (such as FASB Statements of Financial Accounting Standards, FASB Interpretations, FASB Staff Positions, Emerging Issues Task Force Consensuses, other pronouncements of the FASB or other designated bodies, or other forms of GAAP are considered accounting pronouncements) were superseded upon the adoption of the Codification. For an interim period, references to the superseded standards are included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.",
        "label": "Type of Adoption [Domain]",
        "terseLabel": "Type of Adoption [Domain]"
       }
      }
     },
     "localname": "TypeOfAdoptionMember",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_TypeOfArrangementAxis": {
     "auth_ref": [
      "r188"
     ],
     "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 [Axis]"
       }
      }
     },
     "localname": "TypeOfArrangementAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CommitmentsandContingenciesNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_UseOfEstimates": {
     "auth_ref": [
      "r94",
      "r95",
      "r96",
      "r97",
      "r98",
      "r99",
      "r100"
     ],
     "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/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/SummaryofSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_VariableRateAxis": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Information by type of variable rate.",
        "label": "Variable Rate [Axis]",
        "terseLabel": "Variable Rate [Axis]"
       }
      }
     },
     "localname": "VariableRateAxis",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_VariableRateDomain": {
     "auth_ref": [],
     "lang": {
      "en-US": {
       "role": {
        "documentation": "Interest rate that fluctuates over time as a result of an underlying benchmark interest rate or index.",
        "label": "Variable Rate [Domain]",
        "terseLabel": "Variable Rate [Domain]"
       }
      }
     },
     "localname": "VariableRateDomain",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/LoanandSecurityAgreementsNarrativeDetails"
     ],
     "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 number of common shares outstanding, basic and diluted (in shares)"
       }
      }
     },
     "localname": "WeightedAverageNumberOfShareOutstandingBasicAndDiluted",
     "nsuri": "http://fasb.org/us-gaap/2019-01-31",
     "presentation": [
      "http://evelobio.com/role/CondensedConsolidatedStatementsofOperationsandComprehensiveLoss"
     ],
     "xbrltype": "sharesItemType"
    }
   },
   "unitCount": 9
  }
 },
 "std_ref": {
  "r0": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765"
  },
  "r1": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765"
  },
  "r10": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(22))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r100": {
   "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"
  },
  "r101": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "275",
   "URI": "http://asc.fasb.org/topic&trid=2134479"
  },
  "r102": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599"
  },
  "r103": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599"
  },
  "r104": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599"
  },
  "r105": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=118952595&loc=d3e4647-111522"
  },
  "r106": {
   "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=27010918&loc=d3e74512-122707"
  },
  "r107": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "320",
   "URI": "http://asc.fasb.org/extlink&oid=118954083&loc=d3e26853-111562"
  },
  "r108": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919244-210447"
  },
  "r109": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447"
  },
  "r11": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r110": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447"
  },
  "r111": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "16",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447"
  },
  "r112": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447"
  },
  "r113": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955579&loc=SL82922888-210455"
  },
  "r114": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955579&loc=SL82922895-210455"
  },
  "r115": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118955579&loc=SL82922900-210455"
  },
  "r116": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "30",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=118942371&loc=SL82922954-210456"
  },
  "r117": {
   "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"
  },
  "r118": {
   "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"
  },
  "r119": {
   "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"
  },
  "r12": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r120": {
   "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"
  },
  "r121": {
   "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"
  },
  "r122": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "360",
   "URI": "http://asc.fasb.org/topic&trid=2155823"
  },
  "r123": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "440",
   "URI": "http://asc.fasb.org/topic&trid=2144648"
  },
  "r124": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349"
  },
  "r125": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "450",
   "URI": "http://asc.fasb.org/topic&trid=2127136"
  },
  "r126": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601"
  },
  "r127": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(2)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870"
  },
  "r128": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(3)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870"
  },
  "r129": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870"
  },
  "r13": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r130": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "470",
   "URI": "http://asc.fasb.org/topic&trid=2208564"
  },
  "r131": {
   "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=65877616&loc=d3e177068-122764"
  },
  "r132": {
   "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"
  },
  "r133": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21553-112644"
  },
  "r134": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644"
  },
  "r135": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644"
  },
  "r136": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644"
  },
  "r137": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21488-112644"
  },
  "r138": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644"
  },
  "r139": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644"
  },
  "r14": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r140": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644"
  },
  "r141": {
   "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=27012166&loc=d3e187085-122770"
  },
  "r142": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "505",
   "URI": "http://asc.fasb.org/topic&trid=2208762"
  },
  "r143": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(ii)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r144": {
   "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=118255775&loc=d3e1928-114920"
  },
  "r145": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(n)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r146": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921"
  },
  "r147": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "35",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116855982&loc=d3e4534-113899"
  },
  "r148": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901"
  },
  "r149": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901"
  },
  "r15": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r150": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901"
  },
  "r151": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r152": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r153": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(3)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r154": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a),(g)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r155": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b),(f)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r156": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r157": {
   "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=116856206&loc=d3e5070-113901"
  },
  "r158": {
   "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=116856206&loc=d3e5070-113901"
  },
  "r159": {
   "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=116856206&loc=d3e5070-113901"
  },
  "r16": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r160": {
   "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=116856206&loc=d3e5070-113901"
  },
  "r161": {
   "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=116856206&loc=d3e5070-113901"
  },
  "r162": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r163": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r164": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r165": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(g)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r166": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r167": {
   "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=116856206&loc=d3e5070-113901"
  },
  "r168": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r169": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901"
  },
  "r17": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r170": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=116856206&loc=SL79508275-113901"
  },
  "r171": {
   "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=115993241&loc=d3e301413-122809"
  },
  "r172": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=118258462&loc=d3e11149-113907"
  },
  "r173": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=118258462&loc=d3e11178-113907"
  },
  "r174": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "718",
   "URI": "http://asc.fasb.org/topic&trid=2228938"
  },
  "r175": {
   "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"
  },
  "r176": {
   "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"
  },
  "r177": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "730",
   "URI": "http://asc.fasb.org/extlink&oid=6420387&loc=d3e23221-108380"
  },
  "r178": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=116821951&loc=d3e32247-109318"
  },
  "r179": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=116821951&loc=d3e32280-109318"
  },
  "r18": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r180": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32809-109319"
  },
  "r181": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "19",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32840-109319"
  },
  "r182": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32847-109319"
  },
  "r183": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=109238882&loc=d3e38679-109324"
  },
  "r184": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "05",
   "SubTopic": "30",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=65884525&loc=d3e40913-109327"
  },
  "r185": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "740",
   "URI": "http://asc.fasb.org/topic&trid=2144680"
  },
  "r186": {
   "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"
  },
  "r187": {
   "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"
  },
  "r188": {
   "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"
  },
  "r189": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "808",
   "URI": "http://asc.fasb.org/topic&trid=5833765"
  },
  "r19": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r190": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "19",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683"
  },
  "r191": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=108774443&loc=SL4569643-111683"
  },
  "r192": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=109239629&loc=d3e5614-111684"
  },
  "r193": {
   "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"
  },
  "r194": {
   "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"
  },
  "r195": {
   "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"
  },
  "r196": {
   "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"
  },
  "r197": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4J",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116874947&loc=SL4591551-111686"
  },
  "r198": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4K",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116874947&loc=SL4591552-111686"
  },
  "r199": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.3A-02)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116822174&loc=d3e355033-122828"
  },
  "r2": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=118951113&loc=d3e6801-107765"
  },
  "r20": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r200": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.3A-03)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116822174&loc=d3e355100-122828"
  },
  "r201": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "810",
   "URI": "http://asc.fasb.org/topic&trid=2197479"
  },
  "r202": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r203": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r204": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bb)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r205": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r206": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=SL7498348-110258"
  },
  "r207": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19279-110258"
  },
  "r208": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "60",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=7493716&loc=d3e21868-110260"
  },
  "r209": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=118260190&loc=d3e13279-108611"
  },
  "r21": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r210": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "230",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=98513438&loc=d3e33268-110906"
  },
  "r211": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399"
  },
  "r212": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "25",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "840",
   "URI": "http://asc.fasb.org/extlink&oid=77902458&loc=d3e39927-112707"
  },
  "r213": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=119364159&loc=SL77916155-209984"
  },
  "r214": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977"
  },
  "r215": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977"
  },
  "r216": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888419&loc=SL77918638-209977"
  },
  "r217": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(c)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888419&loc=SL77918643-209977"
  },
  "r218": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(e)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980"
  },
  "r219": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(1)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980"
  },
  "r22": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r220": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(3)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980"
  },
  "r221": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(g)(4)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980"
  },
  "r222": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888426&loc=SL77918701-209980"
  },
  "r223": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "53",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971"
  },
  "r224": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "20",
   "Topic": "842",
   "URI": "http://asc.fasb.org/subtopic&trid=77888251"
  },
  "r225": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=119202524&loc=SL77919396-209981"
  },
  "r226": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(b)",
   "Topic": "842",
   "URI": "http://asc.fasb.org/extlink&oid=119202524&loc=SL77919372-209981"
  },
  "r227": {
   "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"
  },
  "r228": {
   "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"
  },
  "r229": {
   "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"
  },
  "r23": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r230": {
   "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"
  },
  "r231": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864"
  },
  "r232": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39678-107864"
  },
  "r233": {
   "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"
  },
  "r234": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "850",
   "URI": "http://asc.fasb.org/topic&trid=2122745"
  },
  "r235": {
   "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"
  },
  "r236": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719"
  },
  "r237": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719"
  },
  "r238": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719"
  },
  "r239": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719"
  },
  "r24": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r240": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "50",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746"
  },
  "r241": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e61929-109447"
  },
  "r242": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e61929-109447"
  },
  "r243": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e62059-109447"
  },
  "r244": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e62059-109447"
  },
  "r245": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e62395-109447"
  },
  "r246": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e62395-109447"
  },
  "r247": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "33",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e62479-109447"
  },
  "r248": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "33",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e62479-109447"
  },
  "r249": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "35A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(a)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=SL6807758-109447"
  },
  "r25": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19(b),22(b))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r250": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "35A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(b)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=SL6807758-109447"
  },
  "r251": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(c)(1)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e61872-109447"
  },
  "r252": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "235",
   "Subparagraph": "(c)(2)",
   "Topic": "932",
   "URI": "http://asc.fasb.org/extlink&oid=68064819&loc=d3e61872-109447"
  },
  "r253": {
   "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=6876686&loc=d3e534808-122878"
  },
  "r254": {
   "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=6876686&loc=d3e534808-122878"
  },
  "r255": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(13))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r256": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(16))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r257": {
   "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=6876686&loc=d3e534808-122878"
  },
  "r258": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.15(3),(4))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878"
  },
  "r259": {
   "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=6876686&loc=d3e534808-122878"
  },
  "r26": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r260": {
   "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=116637391&loc=SL114874048-224260"
  },
  "r261": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(16))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r262": {
   "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=119400593&loc=d3e572229-122910"
  },
  "r263": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(16))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r264": {
   "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=119400593&loc=d3e572229-122910"
  },
  "r265": {
   "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=119400593&loc=d3e572229-122910"
  },
  "r266": {
   "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=119400593&loc=d3e572229-122910"
  },
  "r267": {
   "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=119400593&loc=d3e572229-122910"
  },
  "r268": {
   "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=119400593&loc=d3e572229-122910"
  },
  "r269": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03.17)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910"
  },
  "r27": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r270": {
   "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=116637232&loc=SL114874131-224263"
  },
  "r271": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "210",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=118262064&loc=SL116631418-115840"
  },
  "r272": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "21",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "210",
   "Topic": "946",
   "URI": "http://asc.fasb.org/extlink&oid=118262064&loc=SL116631419-115840"
  },
  "r273": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "740",
   "Topic": "954",
   "URI": "http://asc.fasb.org/extlink&oid=6491622&loc=d3e9504-115650"
  },
  "r274": {
   "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"
  },
  "r275": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b"
  },
  "r276": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "d1-1"
  },
  "r277": {
   "Name": "Form 10-Q",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "13",
   "Subsection": "a-13"
  },
  "r278": {
   "Name": "Forms 10-K, 10-Q, 20-F",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "13",
   "Subsection": "a-1-"
  },
  "r279": {
   "Name": "Regulation 12B",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b-2"
  },
  "r28": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r280": {
   "Name": "Regulation S-T",
   "Number": "232",
   "Publisher": "SEC",
   "Section": "405"
  },
  "r281": {
   "Name": "Securities Act",
   "Number": "7A",
   "Publisher": "SEC",
   "Section": "B",
   "Subsection": "2"
  },
  "r29": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.22(a)(1))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r3": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=118951113&loc=d3e6904-107765"
  },
  "r30": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.22)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r31": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.24)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r32": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r33": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.26(c))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r34": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r35": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r36": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r37": {
   "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"
  },
  "r38": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580"
  },
  "r39": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580"
  },
  "r4": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=118951113&loc=d3e6911-107765"
  },
  "r40": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL34724394-108580"
  },
  "r41": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580"
  },
  "r42": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580"
  },
  "r43": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580"
  },
  "r44": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580"
  },
  "r45": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=118930883&loc=d3e557-108580"
  },
  "r46": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116657188&loc=SL116659661-227067"
  },
  "r47": {
   "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=116634182&loc=SL114868664-224227"
  },
  "r48": {
   "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=116634182&loc=SL114868664-224227"
  },
  "r49": {
   "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=116634182&loc=SL114868664-224227"
  },
  "r5": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r50": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.7(a),(b))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r51": {
   "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=116634182&loc=SL114868664-224227"
  },
  "r52": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.8)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r53": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.9)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227"
  },
  "r54": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3151-108585"
  },
  "r55": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585"
  },
  "r56": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585"
  },
  "r57": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585"
  },
  "r58": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585"
  },
  "r59": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585"
  },
  "r6": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r60": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585"
  },
  "r61": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3367-108585"
  },
  "r62": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3000-108585"
  },
  "r63": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "24",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3521-108585"
  },
  "r64": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3536-108585"
  },
  "r65": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3536-108585"
  },
  "r66": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585"
  },
  "r67": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585"
  },
  "r68": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585"
  },
  "r69": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=118932676&loc=d3e3044-108585"
  },
  "r7": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r70": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4273-108586"
  },
  "r71": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586"
  },
  "r72": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586"
  },
  "r73": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586"
  },
  "r74": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586"
  },
  "r75": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586"
  },
  "r76": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790"
  },
  "r77": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(h))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r78": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(k))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r79": {
   "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=26873400&loc=d3e23780-122690"
  },
  "r8": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(19))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682"
  },
  "r80": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08.(d),(e))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r81": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08.(e),(f))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r82": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08.(h)(1)(i))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r83": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08.(k)(1))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690"
  },
  "r84": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.12-04.(a))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690"
  },
  "r85": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "235",
   "URI": "http://asc.fasb.org/topic&trid=2122369"
  },
  "r86": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r87": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794"
  },
  "r88": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "250",
   "URI": "http://asc.fasb.org/topic&trid=2122394"
  },
  "r89": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=117326831&loc=d3e1337-109256"
  },
  "r9": {
   "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=6877327&loc=d3e13212-122682"
  },
  "r90": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257"
  },
  "r91": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257"
  },
  "r92": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "260",
   "URI": "http://asc.fasb.org/topic&trid=2144383"
  },
  "r93": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "270",
   "URI": "http://asc.fasb.org/extlink&oid=118952077&loc=SL77927221-108306"
  },
  "r94": {
   "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"
  },
  "r95": {
   "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"
  },
  "r96": {
   "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"
  },
  "r97": {
   "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"
  },
  "r98": {
   "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"
  },
  "r99": {
   "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"
  }
 },
 "version": "2.1"
}
