{
 "instance": {
  "mack-10k_20201231.htm": {
   "axisCustom": 0,
   "axisStandard": 25,
   "contextCount": 115,
   "dts": {
    "calculationLink": {
     "local": [
      "mack-20201231_cal.xml"
     ]
    },
    "definitionLink": {
     "local": [
      "mack-20201231_def.xml"
     ],
     "remote": [
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-eedm-def-2020-01-31.xml",
      "http://xbrl.fasb.org/srt/2020/elts/srt-eedm1-def-2020-01-31.xml"
     ]
    },
    "inline": {
     "local": [
      "mack-10k_20201231.htm"
     ]
    },
    "labelLink": {
     "local": [
      "mack-20201231_lab.xml"
     ],
     "remote": [
      "https://xbrl.sec.gov/dei/2020/dei-doc-2020-01-31.xml",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-doc-2020-01-31.xml"
     ]
    },
    "presentationLink": {
     "local": [
      "mack-20201231_pre.xml"
     ]
    },
    "referenceLink": {
     "remote": [
      "https://xbrl.sec.gov/dei/2020/dei-ref-2020-01-31.xml",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-ref-2020-01-31.xml"
     ]
    },
    "schema": {
     "local": [
      "mack-20201231.xsd"
     ],
     "remote": [
      "http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xl-2003-12-31.xsd",
      "http://www.xbrl.org/2003/xlink-2003-12-31.xsd",
      "http://www.xbrl.org/2005/xbrldt-2005.xsd",
      "https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd",
      "http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd",
      "https://xbrl.sec.gov/currency/2020/currency-2020-01-31.xsd",
      "https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd",
      "http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd",
      "https://xbrl.sec.gov/exch/2020/exch-2020-01-31.xsd",
      "http://www.xbrl.org/lrr/arcrole/factExplanatory-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/net-2009-12-16.xsd",
      "https://xbrl.sec.gov/naics/2017/naics-2017-01-31.xsd",
      "https://xbrl.sec.gov/sic/2020/sic-2020-01-31.xsd",
      "http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd",
      "http://www.xbrl.org/2006/ref-2006-02-27.xsd",
      "http://xbrl.fasb.org/srt/2020/elts/srt-types-2020-01-31.xsd",
      "http://xbrl.fasb.org/srt/2020/elts/srt-roles-2020-01-31.xsd",
      "https://xbrl.sec.gov/stpr/2018/stpr-2018-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-roles-2020-01-31.xsd",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-types-2020-01-31.xsd",
      "http://www.xbrl.org/lrr/role/deprecated-2009-12-16.xsd",
      "http://www.xbrl.org/lrr/role/reference-2009-12-16.xsd",
      "http://xbrl.fasb.org/us-gaap/2020/elts/us-parts-codification-2020-01-31.xsd"
     ]
    }
   },
   "elementCount": 439,
   "entityCount": 1,
   "hidden": {
    "http://fasb.org/us-gaap/2020-01-31": 19,
    "http://www.merrimackpharma.com/20201231": 3,
    "http://xbrl.sec.gov/dei/2020-01-31": 8,
    "total": 30
   },
   "keyCustom": 41,
   "keyStandard": 283,
   "memberCustom": 31,
   "memberStandard": 19,
   "nsprefix": "mack",
   "nsuri": "http://www.merrimackpharma.com/20201231",
   "report": {
    "R1": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentType",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "document",
     "isDefault": "true",
     "longName": "100000 - Document - Document and Entity Information",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation",
     "shortName": "Document and Entity Information",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "dei:DocumentType",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R10": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:EarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100090 - Disclosure - Net Loss Per Common Share",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShare",
     "shortName": "Net Loss Per Common Share",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:EarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R11": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CollaborativeArrangementDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100100 - Disclosure - License and Collaboration Agreements",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreements",
     "shortName": "License and Collaboration Agreements",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CollaborativeArrangementDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R12": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100110 - Disclosure - Fair Value of Financial Instruments",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstruments",
     "shortName": "Fair Value of Financial Instruments",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R13": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100120 - Disclosure - Accounts Payable, Accrued Expenses and Other",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOther",
     "shortName": "Accounts Payable, Accrued Expenses and Other",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R14": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100130 - Disclosure - Borrowings",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowings",
     "shortName": "Borrowings",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DebtDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R15": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:RestructuringAndRelatedActivitiesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100140 - Disclosure - Restructuring Activities",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivities",
     "shortName": "Restructuring Activities",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:RestructuringAndRelatedActivitiesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R16": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100150 - Disclosure - Common Stock",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStock",
     "shortName": "Common Stock",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:StockholdersEquityNoteDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R17": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100160 - Disclosure - Stock-Based Compensation",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensation",
     "shortName": "Stock-Based Compensation",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R18": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:IncomeTaxDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100170 - Disclosure - Income Taxes",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxes",
     "shortName": "Income Taxes",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:IncomeTaxDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R19": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CommitmentsAndContingenciesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100180 - Disclosure - Commitments and Contingencies",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingencies",
     "shortName": "Commitments and Contingencies",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CommitmentsAndContingenciesDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R2": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:CashAndCashEquivalentsAtCarryingValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100010 - Statement - Consolidated Balance Sheets",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets",
     "shortName": "Consolidated Balance Sheets",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:CashAndCashEquivalentsAtCarryingValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R20": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CompensationAndEmployeeBenefitPlansTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100190 - Disclosure - Retirement Plan",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRetirementPlan",
     "shortName": "Retirement Plan",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:CompensationAndEmployeeBenefitPlansTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R21": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SegmentReportingPolicyPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100200 - Disclosure - Nature of the Business and Summary of Significant Accounting Policies (Policies)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies",
     "shortName": "Nature of the Business and Summary of Significant Accounting Policies (Policies)",
     "subGroupType": "policies",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:SegmentReportingPolicyPolicyTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R22": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100210 - Disclosure - Discontinued Operations - Sale of Commercial Business (Tables)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessTables",
     "shortName": "Discontinued Operations - Sale of Commercial Business (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R23": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:EarningsPerShareTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100220 - Disclosure - Net Loss Per Common Share (Tables)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareTables",
     "shortName": "Net Loss Per Common Share (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:EarningsPerShareTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R24": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:FairValueDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100230 - Disclosure - Fair Value of Financial Instruments (Tables)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables",
     "shortName": "Fair Value of Financial Instruments (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:FairValueDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R25": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100240 - Disclosure - Accounts Payable, Accrued Expenses and Other (Tables)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherTables",
     "shortName": "Accounts Payable, Accrued Expenses and Other (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R26": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:RestructuringAndRelatedActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfRestructuringAndRelatedCostsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100250 - Disclosure - Restructuring Activities (Tables)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesTables",
     "shortName": "Restructuring Activities (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:RestructuringAndRelatedActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfRestructuringAndRelatedCostsTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R27": {
     "firstAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100260 - Disclosure - Stock-Based Compensation (Tables)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationTables",
     "shortName": "Stock-Based Compensation (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R28": {
     "firstAnchor": {
      "ancestors": [
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100270 - Disclosure - Income Taxes (Tables)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesTables",
     "shortName": "Income Taxes (Tables)",
     "subGroupType": "tables",
     "uniqueAnchor": {
      "ancestors": [
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R29": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ProceedsFromSaleAndMaturityOfMarketableSecurities",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100280 - Disclosure - Nature of the Business and Summary of Significant Accounting Policies - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
     "shortName": "Nature of the Business and Summary of Significant Accounting Policies - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:CashCashEquivalentsAndShortTermInvestments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R3": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:PreferredStockParOrStatedValuePerShare",
      "reportCount": 1,
      "unitRef": "U_iso4217USD_xbrlishares",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100020 - Statement - Consolidated Balance Sheets (Parenthetical)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical",
     "shortName": "Consolidated Balance Sheets (Parenthetical)",
     "subGroupType": "parenthetical",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "INF",
      "lang": null,
      "name": "us-gaap:PreferredStockSharesAuthorized",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     }
    },
    "R30": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100290 - Disclosure - Discontinued Operations - Sale of Commercial Business - Schedule of Discontinued Operations and Assets Held for Sale (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail",
     "shortName": "Discontinued Operations - Sale of Commercial Business - Schedule of Discontinued Operations and Assets Held for Sale (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_mackCommercialBusinessMember_20190101_20191231",
      "decimals": "-3",
      "lang": null,
      "name": "us-gaap:DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R31": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100300 - Disclosure - Discontinued Operations - Sale of Commercial Business - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
     "shortName": "Discontinued Operations - Sale of Commercial Business - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": null
    },
    "R32": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:GainLossOnSaleOfEquityInvestments",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100310 - Disclosure - Investment in Silver Creek - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail",
     "shortName": "Investment in Silver Creek - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:MinorityInterestDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:EquityMethodInvestmentRealizedGainLossOnDisposal",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R33": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:EarningsPerShareTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_us-gaapStockCompensationPlanMember_20200101_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100320 - Disclosure - Net Loss Per Common Share - Schedule of Securities Excluded from Computation of Diluted Loss Per Share (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfSecuritiesExcludedFromComputationOfDilutedLossPerShareDetail",
     "shortName": "Net Loss Per Common Share - Schedule of Securities Excluded from Computation of Diluted Loss Per Share (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "us-gaap:EarningsPerShareTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_us-gaapStockCompensationPlanMember_20200101_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     }
    },
    "R34": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapDeferredRevenueArrangementTypeAxis_mackDevelopmentAndCommercializationMilestonesMember_us-gaapTypeOfArrangementAxis_mackAssetSaleAgreementMember_20190101_20191231",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "mack:MaximumCollaborativeArrangementMilestonePayments",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100330 - Disclosure - License and Collaboration Agreements - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail",
     "shortName": "License and Collaboration Agreements - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:CollaborativeArrangementDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_srtCounterpartyNameAxis_mackIpsenSAMember_us-gaapDeferredRevenueArrangementTypeAxis_mackDevelopmentAndCommercializationMilestonesMember_us-gaapTypeOfArrangementAxis_mackAssetSaleAgreementMember_20170402_20170403",
      "decimals": "INF",
      "lang": null,
      "name": "mack:MaximumCollaborativeArrangementMilestonePayments",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R35": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
       "us-gaap:FairValueDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapFairValueByFairValueHierarchyLevelAxis_us-gaapFairValueInputsLevel1Member_us-gaapFairValueByMeasurementFrequencyAxis_us-gaapFairValueMeasurementsRecurringMember_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:CashAndCashEquivalentsFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100340 - Disclosure - Fair Value of Financial Instruments - Summary of Assets Measured at Fair Value on a Recurring Basis (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail",
     "shortName": "Fair Value of Financial Instruments - Summary of Assets Measured at Fair Value on a Recurring Basis (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:FairValueAssetsMeasuredOnRecurringBasisTextBlock",
       "us-gaap:FairValueDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapFairValueByFairValueHierarchyLevelAxis_us-gaapFairValueInputsLevel1Member_us-gaapFairValueByMeasurementFrequencyAxis_us-gaapFairValueMeasurementsRecurringMember_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:CashAndCashEquivalentsFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R36": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:FairValueDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapFairValueByMeasurementFrequencyAxis_us-gaapFairValueMeasurementsRecurringMember_20201231",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:LiabilitiesFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100350 - Disclosure - Fair Value of Financial Instruments - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetail",
     "shortName": "Fair Value of Financial Instruments - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:FairValueDisclosuresTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapFairValueByMeasurementFrequencyAxis_us-gaapFairValueMeasurementsRecurringMember_20201231",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:LiabilitiesFairValueDisclosure",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R37": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock",
       "us-gaap:AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:AccountsPayableCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100360 - Disclosure - Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail",
     "shortName": "Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock",
       "us-gaap:AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:AccountsPayableCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R38": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:GainsLossesOnExtinguishmentOfDebt",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100370 - Disclosure - Borrowings - Loan Agreement - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
     "shortName": "Borrowings - Loan Agreement - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapTypeOfArrangementAxis_mackLoanAgreementMember_20190101_20191231",
      "decimals": "-5",
      "lang": null,
      "name": "us-gaap:InterestExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R39": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfRestructuringAndRelatedCostsTextBlock",
       "us-gaap:RestructuringAndRelatedActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:RestructuringCharges",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100380 - Disclosure - Restructuring Activities - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
     "shortName": "Restructuring Activities - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:RestructuringAndRelatedActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapRestructuringCostAndReserveAxis_us-gaapOneTimeTerminationBenefitsMember_20200101_20201231",
      "decimals": "-6",
      "lang": null,
      "name": "us-gaap:RestructuringCharges",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R4": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ResearchAndDevelopmentExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100030 - Statement - Consolidated Statements of Operations and Comprehensive Loss",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss",
     "shortName": "Consolidated Statements of Operations and Comprehensive Loss",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ResearchAndDevelopmentExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R40": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock",
       "us-gaap:AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:RestructuringReserveCurrent",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100390 - Disclosure - Restructuring Activities - Summary of Charges Related to Restructuring Activities (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail",
     "shortName": "Restructuring Activities - Summary of Charges Related to Restructuring Activities (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfRestructuringAndRelatedCostsTextBlock",
       "us-gaap:RestructuringAndRelatedActivitiesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapRestructuringCostAndReserveAxis_us-gaapEmployeeSeveranceMember_20181231",
      "decimals": "-3",
      "lang": null,
      "name": "us-gaap:RestructuringReserveCurrent",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R41": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:CommonStockSharesIssued",
      "reportCount": 1,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100400 - Disclosure - Common Stock - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
     "shortName": "Common Stock - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapTypeOfArrangementAxis_mackRightsAgreementMember_20191231",
      "decimals": "INF",
      "lang": null,
      "name": "us-gaap:CommonStockParOrStatedValuePerShare",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD_xbrlishares",
      "xsiNil": "false"
     }
    },
    "R42": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20191203_20191203",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:DividendsCommonStockCash",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100410 - Disclosure - Stock-Based Compensation - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail",
     "shortName": "Stock-Based Compensation - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "2",
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD_xbrlishares",
      "xsiNil": "false"
     }
    },
    "R43": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapAwardTypeAxis_us-gaapEmployeeStockOptionMember_20200101_20201231",
      "decimals": "3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100420 - Disclosure - Stock-Based Compensation - Schedule of Assumptions Used to Calculate Fair Value of Options Granted to Employees (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail",
     "shortName": "Stock-Based Compensation - Schedule of Assumptions Used to Calculate Fair Value of Options Granted to Employees (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapAwardTypeAxis_us-gaapEmployeeStockOptionMember_20200101_20201231",
      "decimals": "3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     }
    },
    "R44": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "mack:AllocatedShareBasedCompensationExpenseIncludingNonEmployees",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100430 - Disclosure - Stock-Based Compensation - Schedule of Recognized Stock-Based Compensation Expense (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail",
     "shortName": "Stock-Based Compensation - Schedule of Recognized Stock-Based Compensation Expense (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "mack:ScheduleOfEmployeeAndNonemployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_us-gaapIncomeStatementLocationAxis_us-gaapResearchAndDevelopmentExpenseMember_20190101_20191231",
      "decimals": "-3",
      "lang": null,
      "name": "us-gaap:AllocatedShareBasedCompensationExpense",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R45": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber",
      "reportCount": 1,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100440 - Disclosure - Stock-Based Compensation - Summary of Stock Option Activity (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail",
     "shortName": "Stock-Based Compensation - Summary of Stock Option Activity (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "-3",
      "lang": null,
      "name": "us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlishares",
      "xsiNil": "false"
     }
    },
    "R46": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:IncomeTaxExpenseBenefit",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100450 - Disclosure - Income Taxes - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail",
     "shortName": "Income Taxes - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "-5",
      "lang": null,
      "name": "mack:FederalOrphanDrugCredits",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R47": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock",
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100460 - Disclosure - Income Taxes - Schedule of Reconciliation of the Company's Effective Tax Rate to the Statutory Federal Income Tax Rate (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail",
     "shortName": "Income Taxes - Schedule of Reconciliation of the Company's Effective Tax Rate to the Statutory Federal Income Tax Rate (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock",
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "INF",
      "first": true,
      "lang": null,
      "name": "us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_xbrlipure",
      "xsiNil": "false"
     }
    },
    "R48": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock",
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:DeferredTaxAssetsOperatingLossCarryforwards",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100470 - Disclosure - Income Taxes - Schedule of Temporary Differences That Give Rise to Significant Net Deferred Tax Assets (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail",
     "shortName": "Income Taxes - Schedule of Temporary Differences That Give Rise to Significant Net Deferred Tax Assets (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock",
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:DeferredTaxAssetsOperatingLossCarryforwards",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R49": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "us-gaap:ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock",
       "us-gaap:IncomeTaxDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20191231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:DeferredTaxAssetsValuationAllowance",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100480 - Disclosure - Income Taxes - Schedule of Changes in the Valuation Allowance (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfChangesInValuationAllowanceDetail",
     "shortName": "Income Taxes - Schedule of Changes in the Valuation Allowance (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "ix:continuation",
       "ix:continuation",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "-3",
      "lang": null,
      "name": "mack:ValuationAllowanceDeferredTaxAssetAdditions",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R5": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20181231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:StockholdersEquity",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100040 - Statement - Consolidated Statements of Stockholders' Equity",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity",
     "shortName": "Consolidated Statements of Stockholders' Equity",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20181231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:StockholdersEquity",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R50": {
     "firstAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:CommitmentsAndContingenciesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_srtRangeAxis_srtMaximumMember_us-gaapDeferredRevenueArrangementTypeAxis_mackSubleaseAgreementMember_20190101_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:OperatingLeasesRentExpenseNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100490 - Disclosure - Commitments and Contingencies - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail",
     "shortName": "Commitments and Contingencies - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "span",
       "p",
       "us-gaap:CommitmentsAndContingenciesDisclosureTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_srtRangeAxis_srtMaximumMember_us-gaapDeferredRevenueArrangementTypeAxis_mackSubleaseAgreementMember_20190101_20191231",
      "decimals": "-5",
      "first": true,
      "lang": null,
      "name": "us-gaap:OperatingLeasesRentExpenseNet",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R51": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "us-gaap:CompensationAndEmployeeBenefitPlansTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "-6",
      "first": true,
      "lang": null,
      "name": "us-gaap:DefinedContributionPlanEmployerDiscretionaryContributionAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100500 - Disclosure - Retirement Plan - Additional Information (Detail)",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRetirementPlanAdditionalInformationDetail",
     "shortName": "Retirement Plan - Additional Information (Detail)",
     "subGroupType": "details",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "us-gaap:CompensationAndEmployeeBenefitPlansTextBlock",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "-6",
      "first": true,
      "lang": null,
      "name": "us-gaap:DefinedContributionPlanEmployerDiscretionaryContributionAmount",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R6": {
     "firstAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": "-3",
      "first": true,
      "lang": null,
      "name": "us-gaap:ProfitLoss",
      "reportCount": 1,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     },
     "groupType": "statement",
     "isDefault": "false",
     "longName": "100050 - Statement - Consolidated Statements of Cash Flows",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows",
     "shortName": "Consolidated Statements of Cash Flows",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "p",
       "td",
       "tr",
       "table",
       "div",
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20190101_20191231",
      "decimals": "-3",
      "lang": null,
      "name": "us-gaap:PaidInKindInterest",
      "reportCount": 1,
      "unique": true,
      "unitRef": "U_iso4217USD",
      "xsiNil": "false"
     }
    },
    "R7": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100060 - Disclosure - Nature of the Business and Summary of Significant Accounting Policies",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPolicies",
     "shortName": "Nature of the Business and Summary of Significant Accounting Policies",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R8": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100070 - Disclosure - Discontinued Operations - Sale of Commercial Business",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusiness",
     "shortName": "Discontinued Operations - Sale of Commercial Business",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    },
    "R9": {
     "firstAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:MinorityInterestDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     },
     "groupType": "disclosure",
     "isDefault": "false",
     "longName": "100080 - Disclosure - Investment in Silver Creek",
     "role": "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreek",
     "shortName": "Investment in Silver Creek",
     "subGroupType": "",
     "uniqueAnchor": {
      "ancestors": [
       "body",
       "html"
      ],
      "baseRef": "mack-10k_20201231.htm",
      "contextRef": "C_0001274792_20200101_20201231",
      "decimals": null,
      "first": true,
      "lang": "en-US",
      "name": "us-gaap:MinorityInterestDisclosureTextBlock",
      "reportCount": 1,
      "unique": true,
      "unitRef": null,
      "xsiNil": "false"
     }
    }
   },
   "segmentCount": 50,
   "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_CityAreaCode": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Area code of city",
        "label": "City Area Code",
        "terseLabel": "City Area Code"
       }
      }
     },
     "localname": "CityAreaCode",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_CoverAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cover page.",
        "label": "Cover [Abstract]"
       }
      }
     },
     "localname": "CoverAbstract",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "gMonthDayItemType"
    },
    "dei_DocumentAnnualReport": {
     "auth_ref": [
      "r401",
      "r402",
      "r403"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Boolean flag that is true only for a form used as an annual report.",
        "label": "Document Annual Report",
        "terseLabel": "Document Annual Report"
       }
      }
     },
     "localname": "DocumentAnnualReport",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "fiscalPeriodItemType"
    },
    "dei_DocumentFiscalYearFocus": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "This is focus fiscal year of the document report in YYYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006.",
        "label": "Document Fiscal Year Focus",
        "terseLabel": "Document Fiscal Year Focus"
       }
      }
     },
     "localname": "DocumentFiscalYearFocus",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "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 YYYY-MM-DD.",
        "label": "Document Period End Date",
        "terseLabel": "Document Period End Date"
       }
      }
     },
     "localname": "DocumentPeriodEndDate",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "dateItemType"
    },
    "dei_DocumentTransitionReport": {
     "auth_ref": [
      "r404"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_DocumentType": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.",
        "label": "Document Type",
        "terseLabel": "Document Type"
       }
      }
     },
     "localname": "DocumentType",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "submissionTypeItemType"
    },
    "dei_DocumentsIncorporatedByReferenceTextBlock": {
     "auth_ref": [
      "r399"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Documents incorporated by reference.",
        "label": "Documents Incorporated By Reference [Text Block]",
        "terseLabel": "Documents Incorporated by Reference [Text Block]"
       }
      }
     },
     "localname": "DocumentsIncorporatedByReferenceTextBlock",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "textBlockItemType"
    },
    "dei_EntityAddressAddressLine1": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Address Line 1 such as Attn, Building Name, Street Name",
        "label": "Entity Address Address Line1",
        "terseLabel": "Entity Address, Address Line One"
       }
      }
     },
     "localname": "EntityAddressAddressLine1",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressAddressLine2": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Address Line 2 such as Street or Suite number",
        "label": "Entity Address Address Line2",
        "terseLabel": "Entity Address, Address Line Two"
       }
      }
     },
     "localname": "EntityAddressAddressLine2",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressCityOrTown": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Name of the City or Town",
        "label": "Entity Address City Or Town",
        "terseLabel": "Entity Address, City or Town"
       }
      }
     },
     "localname": "EntityAddressCityOrTown",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressPostalZipCode": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Code for the postal or zip code",
        "label": "Entity Address Postal Zip Code",
        "terseLabel": "Entity Address, Postal Zip Code"
       }
      }
     },
     "localname": "EntityAddressPostalZipCode",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityAddressStateOrProvince": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Name of the state or province.",
        "label": "Entity Address State Or Province",
        "terseLabel": "Entity Address, State or Province"
       }
      }
     },
     "localname": "EntityAddressStateOrProvince",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "stateOrProvinceItemType"
    },
    "dei_EntityCentralIndexKey": {
     "auth_ref": [
      "r405"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "centralIndexKeyItemType"
    },
    "dei_EntityCommonStockSharesOutstanding": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.",
        "label": "Entity Common Stock Shares Outstanding",
        "terseLabel": "Entity Common Stock, Shares Outstanding"
       }
      }
     },
     "localname": "EntityCommonStockSharesOutstanding",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "sharesItemType"
    },
    "dei_EntityCurrentReportingStatus": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate 'Yes' or 'No' whether registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that registrants were required to file such reports), and (2) have been subject to such filing requirements for the past 90 days. This information should be based on the registrant's current or most recent filing containing the related disclosure.",
        "label": "Entity Current Reporting Status",
        "terseLabel": "Entity Current Reporting Status"
       }
      }
     },
     "localname": "EntityCurrentReportingStatus",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "All the names of the entities being reported upon in a document. Any legal structure used to conduct activities or to hold assets. Some examples of such structures are corporations, partnerships, limited liability companies, grantor trusts, and other trusts. This item does not include business and geographical segments which are included in the geographical or business segments domains.",
        "label": "Entity [Domain]",
        "terseLabel": "Entity"
       }
      }
     },
     "localname": "EntityDomain",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "dei_EntityEmergingGrowthCompany": {
     "auth_ref": [
      "r405"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityFileNumber": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.",
        "label": "Entity File Number",
        "terseLabel": "Entity File Number"
       }
      }
     },
     "localname": "EntityFileNumber",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "fileNumberItemType"
    },
    "dei_EntityFilerCategory": {
     "auth_ref": [
      "r405"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "filerCategoryItemType"
    },
    "dei_EntityIncorporationStateCountryCode": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Two-character EDGAR code representing the state or country of incorporation.",
        "label": "Entity Incorporation State Country Code",
        "terseLabel": "Entity Incorporation, State or Country Code"
       }
      }
     },
     "localname": "EntityIncorporationStateCountryCode",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "edgarStateCountryItemType"
    },
    "dei_EntityInteractiveDataCurrent": {
     "auth_ref": [
      "r406"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityPublicFloat": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The aggregate market value of the voting and non-voting common equity held by non-affiliates computed by reference to the price at which the common equity was last sold, or the average bid and asked price of such common equity, as of the last business day of the registrant's most recently completed second fiscal quarter.",
        "label": "Entity Public Float",
        "terseLabel": "Entity Public Float"
       }
      }
     },
     "localname": "EntityPublicFloat",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "monetaryItemType"
    },
    "dei_EntityRegistrantName": {
     "auth_ref": [
      "r405"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_EntityShellCompany": {
     "auth_ref": [
      "r405"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntitySmallBusiness": {
     "auth_ref": [
      "r405"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_EntityTaxIdentificationNumber": {
     "auth_ref": [
      "r405"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "employerIdItemType"
    },
    "dei_EntityVoluntaryFilers": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate 'Yes' or 'No' if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.",
        "label": "Entity Voluntary Filers",
        "terseLabel": "Entity Voluntary Filers"
       }
      }
     },
     "localname": "EntityVoluntaryFilers",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_EntityWellKnownSeasonedIssuer": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Indicate 'Yes' or 'No' if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Is used on Form Type: 10-K, 10-Q, 8-K, 20-F, 6-K, 10-K/A, 10-Q/A, 20-F/A, 6-K/A, N-CSR, N-Q, N-1A.",
        "label": "Entity Well Known Seasoned Issuer",
        "terseLabel": "Entity Well-known Seasoned Issuer"
       }
      }
     },
     "localname": "EntityWellKnownSeasonedIssuer",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "yesNoItemType"
    },
    "dei_IcfrAuditorAttestationFlag": {
     "auth_ref": [
      "r401",
      "r402",
      "r403"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Icfr Auditor Attestation Flag",
        "terseLabel": "ICFR Auditor Attestation Flag"
       }
      }
     },
     "localname": "IcfrAuditorAttestationFlag",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "booleanItemType"
    },
    "dei_LegalEntityAxis": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The set of legal entities associated with a report.",
        "label": "Legal Entity [Axis]",
        "terseLabel": "Legal Entity"
       }
      }
     },
     "localname": "LegalEntityAxis",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "normalizedStringItemType"
    },
    "dei_Security12bTitle": {
     "auth_ref": [
      "r398"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Title of a 12(b) registered security.",
        "label": "Security12b Title",
        "terseLabel": "Title of 12(b) Security"
       }
      }
     },
     "localname": "Security12bTitle",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "securityTitleItemType"
    },
    "dei_SecurityExchangeName": {
     "auth_ref": [
      "r400"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "edgarExchangeCodeItemType"
    },
    "dei_TradingSymbol": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Trading symbol of an instrument as listed on an exchange.",
        "label": "Trading Symbol",
        "terseLabel": "Trading Symbol"
       }
      }
     },
     "localname": "TradingSymbol",
     "nsuri": "http://xbrl.sec.gov/dei/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DocumentDocumentAndEntityInformation"
     ],
     "xbrltype": "tradingSymbolItemType"
    },
    "mack_AccruedAndOtherLiabilities": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail": {
       "order": 10070.0,
       "parentTag": "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accrued and other liabilities.",
        "label": "Accrued And Other Liabilities",
        "terseLabel": "Others"
       }
      }
     },
     "localname": "AccruedAndOtherLiabilities",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_AccruedClinicalTrialCosts": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail": {
       "order": 10030.0,
       "parentTag": "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Carrying value as of the balance sheet date of obligations incurred through that date arising from ongoing clinical trial activity.",
        "label": "Accrued Clinical Trial Costs",
        "verboseLabel": "Accrued clinical trial costs"
       }
      }
     },
     "localname": "AccruedClinicalTrialCosts",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_AccruedDrugPurchaseCostsCurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail": {
       "order": 10040.0,
       "parentTag": "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accrued drug purchase costs current.",
        "label": "Accrued Drug Purchase Costs Current",
        "terseLabel": "Accrued drug purchase costs"
       }
      }
     },
     "localname": "AccruedDrugPurchaseCostsCurrent",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_AccruedExpensesPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Accrued expenses policy.",
        "label": "Accrued Expenses Policy [Text Block]",
        "terseLabel": "Accrued Expenses"
       }
      }
     },
     "localname": "AccruedExpensesPolicyTextBlock",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "mack_AcquiringBeneficialOwnershipPercentageOfCommonStockOutstanding": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Acquiring beneficial ownership percentage of common stock outstanding.",
        "label": "Acquiring Beneficial Ownership Percentage Of Common Stock Outstanding",
        "terseLabel": "Acquiring beneficial ownership percentage of common stock outstanding"
       }
      }
     },
     "localname": "AcquiringBeneficialOwnershipPercentageOfCommonStockOutstanding",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "mack_AdditionalIndicationMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Additional Indication [Member]",
        "terseLabel": "Additional Indication [Member]"
       }
      }
     },
     "localname": "AdditionalIndicationMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_AdditionalLoanAdvancesUponOccurrenceOfCertainFundingConditions": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Additional loan advances upon occurrence of certain funding conditions.",
        "label": "Additional Loan Advances Upon Occurrence Of Certain Funding Conditions",
        "terseLabel": "Debt instrument, initial advance amount"
       }
      }
     },
     "localname": "AdditionalLoanAdvancesUponOccurrenceOfCertainFundingConditions",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_AdditionalPaymentsReceivableOnAchievementOfCertainMilestoneEvents": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Additional payments receivable on achievement of certain milestone events.",
        "label": "Additional Payments Receivable On Achievement Of Certain Milestone Events",
        "terseLabel": "Additional payments receivable on achievement of certain milestone events"
       }
      }
     },
     "localname": "AdditionalPaymentsReceivableOnAchievementOfCertainMilestoneEvents",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_AfterFailureOfFirstLineChemotherapyMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "After Failure Of First Line Chemotherapy [Member]",
        "terseLabel": "After Failure of First Line Chemotherapy [Member]"
       }
      }
     },
     "localname": "AfterFailureOfFirstLineChemotherapyMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_AllocatedShareBasedCompensationExpenseIncludingNonEmployees": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10220.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and nonemployees.",
        "label": "Allocated Share Based Compensation Expense Including Non Employees",
        "terseLabel": "Stock-based compensation expense",
        "totalLabel": "Total stock-based compensation expense"
       }
      }
     },
     "localname": "AllocatedShareBasedCompensationExpenseIncludingNonEmployees",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_AmortizationAndAccretionOnMarketableSecurities": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10160.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amortization and accretion on marketable securities.",
        "label": "Amortization And Accretion On Marketable Securities",
        "negatedLabel": "Amortization and accretion on marketable securities"
       }
      }
     },
     "localname": "AmortizationAndAccretionOnMarketableSecurities",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_AssetSaleAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Asset sale agreement.",
        "label": "Asset Sale Agreement [Member]",
        "terseLabel": "Asset Sale Agreement [Member]"
       }
      }
     },
     "localname": "AssetSaleAgreementMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_BasisOfAccountingAndConsolidationPolicyTextBlock": {
     "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). Also includes the 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": "Basis Of Accounting And Consolidation Policy [Text Block]",
        "terseLabel": "Basis of Presentation and Consolidation"
       }
      }
     },
     "localname": "BasisOfAccountingAndConsolidationPolicyTextBlock",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "mack_CashPaymentReceived": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash payment received.",
        "label": "Cash Payment Received",
        "terseLabel": "Cash payment received"
       }
      }
     },
     "localname": "CashPaymentReceived",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_CelatorPharmaceuticalsIncMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Celator Pharmaceuticals Inc [Member].",
        "label": "Celator Pharmaceuticals Inc [Member]",
        "terseLabel": "Celator Pharmaceuticals Inc [Member]"
       }
      }
     },
     "localname": "CelatorPharmaceuticalsIncMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_CollaborationArrangementDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Collaboration Arrangement Disclosure [Abstract]",
        "label": "Collaboration Arrangement Disclosure [Abstract]"
       }
      }
     },
     "localname": "CollaborationArrangementDisclosureAbstract",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "xbrltype": "stringItemType"
    },
    "mack_CommercialBusinessMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Commercial business.",
        "label": "Commercial Business [Member]",
        "terseLabel": "Commercial Business [Member]"
       }
      }
     },
     "localname": "CommercialBusinessMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_ComputershareTrustCompanyNMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Represents the information pertaining to Computershare Trust Company, N.A.",
        "label": "Computershare Trust Company N [Member]",
        "terseLabel": "Computershare Trust Company N.A [Member]"
       }
      }
     },
     "localname": "ComputershareTrustCompanyNMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_ContingentMilestonePaymentsReceivable": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Contingent milestone payments receivable.",
        "label": "Contingent Milestone Payments Receivable",
        "terseLabel": "Contingent milestone payments receivable"
       }
      }
     },
     "localname": "ContingentMilestonePaymentsReceivable",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_DebtInstrumentPrepaymentFee": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Debt instrument prepayment fee",
        "label": "Debt Instrument Prepayment Fee",
        "terseLabel": "Prepayment fee"
       }
      }
     },
     "localname": "DebtInstrumentPrepaymentFee",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_DebtInstrumentPrepaymentPenalty": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Debt instrument prepayment penalty.",
        "label": "Debt Instrument Prepayment Penalty",
        "terseLabel": "Prepayment penalty"
       }
      }
     },
     "localname": "DebtInstrumentPrepaymentPenalty",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_DebtInstrumentPrepaymentsOfDebt": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Debt instrument prepayments of debt.",
        "label": "Debt Instrument Prepayments Of Debt",
        "terseLabel": "Payoff amount"
       }
      }
     },
     "localname": "DebtInstrumentPrepaymentsOfDebt",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_DecemberSpecialDividendMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "December special dividend.",
        "label": "December Special Dividend [Member]",
        "terseLabel": "December Special Dividend [Member]"
       }
      }
     },
     "localname": "DecemberSpecialDividendMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_DeferredTaxAssetsDeferredExpenseCapitalizedResearchAndDevelopmentCosts": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": 10020.0,
       "parentTag": "us-gaap_DeferredTaxAssetsGross",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The tax effect as of the balance sheet date of the amount of the estimated future tax deductions attributable to capitalized research and development costs, which can only be deducted for tax purposes at a later date and which can only be realized, if sufficient tax-basis income is generated in future periods to enable the deduction to be taken.",
        "label": "Deferred Tax Assets Deferred Expense Capitalized Research And Development Costs",
        "terseLabel": "Capitalized research and development expenses"
       }
      }
     },
     "localname": "DeferredTaxAssetsDeferredExpenseCapitalizedResearchAndDevelopmentCosts",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_DeferredTaxAssetsInstallmentSaleTaxBasis": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": 10080.0,
       "parentTag": "us-gaap_DeferredTaxAssetsGross",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Deferred tax assets installment sale tax basis.",
        "label": "Deferred Tax Assets Installment Sale Tax Basis",
        "terseLabel": "Installment sale tax basis"
       }
      }
     },
     "localname": "DeferredTaxAssetsInstallmentSaleTaxBasis",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_DeferredTaxAssetsTaxElectionOutOfInstallmentMethod": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": 10050.0,
       "parentTag": "us-gaap_DeferredTaxAssetsGross",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Deferred tax assets tax election out of installment method",
        "label": "Deferred Tax Assets Tax Election Out Of Installment Method",
        "terseLabel": "Election out of installment method"
       }
      }
     },
     "localname": "DeferredTaxAssetsTaxElectionOutOfInstallmentMethod",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_DevelopmentAndCommercializationMilestonesMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Development and commercialization milestones.",
        "label": "Development And Commercialization Milestones [Member]",
        "terseLabel": "Development and Commercialization Milestones [Member]"
       }
      }
     },
     "localname": "DevelopmentAndCommercializationMilestonesMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_DisposalGroupIncludingDiscontinuedOperationOtherIncomeAndExpensesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disposal group including discontinued operation other income and expenses.",
        "label": "Disposal Group Including Discontinued Operation Other Income And Expenses [Abstract]",
        "terseLabel": "Other income and expenses:"
       }
      }
     },
     "localname": "DisposalGroupIncludingDiscontinuedOperationOtherIncomeAndExpensesAbstract",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "mack_DisposalGroupIncludingDiscontinuedOperationResearchAndDevelopmentExpenses": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disposal group including discontinued operation research and development expenses.",
        "label": "Disposal Group Including Discontinued Operation Research And Development Expenses",
        "verboseLabel": "Research and development expense"
       }
      }
     },
     "localname": "DisposalGroupIncludingDiscontinuedOperationResearchAndDevelopmentExpenses",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_EffectiveIncomeTaxRateReconciliationForfeitureOfVestedStockOptionsPercent": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": 10060.0,
       "parentTag": "us-gaap_EffectiveIncomeTaxRateContinuingOperations",
       "weight": -1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Effective income tax rate reconciliation forfeiture of vested stock options percent.",
        "label": "Effective Income Tax Rate Reconciliation Forfeiture Of Vested Stock Options Percent",
        "negatedLabel": "Forfeiture of vested stock options"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateReconciliationForfeitureOfVestedStockOptionsPercent",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "mack_EffectiveIncomeTaxRateReconciliationRecaptureOfTaxCredits": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": 10050.0,
       "parentTag": "us-gaap_EffectiveIncomeTaxRateContinuingOperations",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Effective income tax rate reconciliation recapture of tax credits",
        "label": "Effective Income Tax Rate Reconciliation Recapture Of Tax Credits",
        "terseLabel": "Recapture of tax credits"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateReconciliationRecaptureOfTaxCredits",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "mack_EmployeeMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Employee.",
        "label": "Employee [Member]",
        "terseLabel": "Employee [Member]"
       }
      }
     },
     "localname": "EmployeeMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_FederalOrphanDrugCredits": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Federal orphan drug credits.",
        "label": "Federal Orphan Drug Credits",
        "terseLabel": "Federal orphan drug credits"
       }
      }
     },
     "localname": "FederalOrphanDrugCredits",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_FederalOrphanDrugCreditsExpirationStartYear": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Federal orphan drug credits expiration start year.",
        "label": "Federal Orphan Drug Credits Expiration Start Year",
        "terseLabel": "Federal orphan drug credits begin to expire"
       }
      }
     },
     "localname": "FederalOrphanDrugCreditsExpirationStartYear",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "gYearItemType"
    },
    "mack_FirstLineTreatmentOfMetastaticAdenocarcinomaOfPancreasMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "First Line Treatment Of Metastatic Adenocarcinoma Of Pancreas [Member]",
        "terseLabel": "First Line Treatment of Metastatic Adenocarcinoma of Pancreas [Member]"
       }
      }
     },
     "localname": "FirstLineTreatmentOfMetastaticAdenocarcinomaOfPancreasMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_FourteenerOncologyIncMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Fourteener oncology inc member.",
        "label": "Fourteener Oncology Inc [Member]",
        "terseLabel": "14ner Sale [Member]"
       }
      }
     },
     "localname": "FourteenerOncologyIncMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_GainOnSaleOfInProcessResearchAndDevelopmentAsset": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10200.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Gain on sale of in progress research and development asset.",
        "label": "Gain On Sale Of In Process Research And Development Asset",
        "negatedLabel": "Gain on sale of in-process research and development asset"
       }
      }
     },
     "localname": "GainOnSaleOfInProcessResearchAndDevelopmentAsset",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_HerculesCapitalIncMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Hercules Capital Inc.",
        "label": "Hercules Capital Inc [Member]",
        "terseLabel": "Hercules Capital, Inc [Member]"
       }
      }
     },
     "localname": "HerculesCapitalIncMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_IpsenSAMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Ipsen S.A.",
        "label": "Ipsen S A [Member]",
        "terseLabel": "Ipsen [Member]"
       }
      }
     },
     "localname": "IpsenSAMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_LaboratoryEquipmentMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Laboratory equipment from its research and development operations.",
        "label": "Laboratory Equipment [Member]",
        "terseLabel": "Laboratory Equipment [Member]"
       }
      }
     },
     "localname": "LaboratoryEquipmentMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_LoanAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Loan agreement.",
        "label": "Loan Agreement [Member]",
        "terseLabel": "Loan Agreement [Member]"
       }
      }
     },
     "localname": "LoanAgreementMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_MaximumCollaborativeArrangementMilestonePayments": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Represents the maximum cumulative amount of milestone payments that can be received over the life of the license and collaboration agreements.",
        "label": "Maximum Collaborative Arrangement Milestone Payments",
        "terseLabel": "Maximum amount of milestone payments that can be received"
       }
      }
     },
     "localname": "MaximumCollaborativeArrangementMilestonePayments",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_MaximumMaturityPeriodForInvestmentsToBeClassifiedAsCashAndCashEquivalentsDescription": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Maximum maturity period for investments to be classified as cash and cash equivalents description.",
        "label": "Maximum Maturity Period For Investments To Be Classified As Cash And Cash Equivalents Description",
        "terseLabel": "Original maturities"
       }
      }
     },
     "localname": "MaximumMaturityPeriodForInvestmentsToBeClassifiedAsCashAndCashEquivalentsDescription",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "mack_MilestoneAchievementOneMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Milestone achievement one member.",
        "label": "Milestone Achievement One [Member]",
        "terseLabel": "Achievement of the Primary Endpoint in the First Registrational Clinical Study of Either MM-121 or MM-111 [Member]"
       }
      }
     },
     "localname": "MilestoneAchievementOneMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_MilestoneAchievementThreeMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Milestone achievement three member.",
        "label": "Milestone Achievement Three [Member]",
        "terseLabel": "Achievement Various Cumulative Worldwide Net Sales Targets Between $100.0 million and $300.0 million for MM-121 and MM-111 [Member]"
       }
      }
     },
     "localname": "MilestoneAchievementThreeMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_MilestoneAchievementTwoMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Milestone achievement two member.",
        "label": "Milestone Achievement Two [Member]",
        "terseLabel": "Achievement of Various Regulatory Approval and Reimbursement-Based Milestones in the United States, Europe and Japan [Member]"
       }
      }
     },
     "localname": "MilestoneAchievementTwoMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_NonEmployeeConsultantsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Non Employee Consultants [Member]",
        "label": "Non Employee Consultants [Member]",
        "terseLabel": "Non-Employee Consultants [Member]"
       }
      }
     },
     "localname": "NonEmployeeConsultantsMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_NonEmployeeDirectorsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Non-employee directors.",
        "label": "Non Employee Directors [Member]",
        "terseLabel": "Non-Employee Directors [Member]"
       }
      }
     },
     "localname": "NonEmployeeDirectorsMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_NovemberTwoThousandEighteenCorporateRestructuringMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "November two thousand eighteen corporate restructuring.",
        "label": "November Two Thousand Eighteen Corporate Restructuring [Member]",
        "terseLabel": "November 2018 Corporate Restructuring [Member]"
       }
      }
     },
     "localname": "NovemberTwoThousandEighteenCorporateRestructuringMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_NumberOfAdditionalOptionalTermLoanAdvances": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of additional optional term loan advances.",
        "label": "Number Of Additional Optional Term Loan Advances",
        "terseLabel": "Number of additional optional term loan advances"
       }
      }
     },
     "localname": "NumberOfAdditionalOptionalTermLoanAdvances",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "integerItemType"
    },
    "mack_NumberOfGeographicSegments": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of geographic segments. A geographic 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 units located at different geographic location of the same enterprise), (b) whose 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.",
        "label": "Number Of Geographic Segments",
        "terseLabel": "Number of geographic regions"
       }
      }
     },
     "localname": "NumberOfGeographicSegments",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "positiveIntegerItemType"
    },
    "mack_OngoingMultiPartClinicalMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Ongoing multi part clinical.",
        "label": "Ongoing Multi Part Clinical [Member]",
        "terseLabel": "Ongoing Multi Part Clinical [Member]"
       }
      }
     },
     "localname": "OngoingMultiPartClinicalMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_OperatingLossCarryforwardsExpirationStartYear": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Operating loss carryforwards expiration start year.",
        "label": "Operating Loss Carryforwards Expiration Start Year",
        "terseLabel": "Net operating loss carryforwards expire year begin"
       }
      }
     },
     "localname": "OperatingLossCarryforwardsExpirationStartYear",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "gYearItemType"
    },
    "mack_PercentageOfMinimumVarianceForUpwardPurchasePriceAdjustment": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "This element represents that, the percentage of minimum variance for upward purchase price adjustment.",
        "label": "Percentage Of Minimum Variance For Upward Purchase Price Adjustment",
        "terseLabel": "Percentage of minimum variance for upward purchase price adjustment"
       }
      }
     },
     "localname": "PercentageOfMinimumVarianceForUpwardPurchasePriceAdjustment",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "mack_PercentageTransferThresholdAssetsCashflowEarningPower": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "In the event that, at any time following the first date of a public announcement that a Person has become an Acquiring Person or that discloses information which reveals the existence of an Acquiring Person or such earlier date as a majority of the Board becomes aware of the existence of an Acquiring Person (any such date, the Stock Acquisition Date), (i) the Company engages in a merger or other business combination transaction in which the Company is not the surviving corporation, (ii) the Company engages in a merger or other business combination transaction in which the Company is the surviving corporation and the common stock of the Company is changed or exchanged or (iii) 50% or more of the Company\u2019s assets, cash flow or earning power is sold or transferred, each holder of a Right (except Rights which have previously been voided as set forth above) shall thereafter have the right to receive, upon exercise, common stock of the acquiring company having a value equal to two times the purchase price.",
        "label": "Percentage Transfer Threshold Assets Cashflow Earning Power",
        "terseLabel": "Percentage transfer consolidated assets or earning power"
       }
      }
     },
     "localname": "PercentageTransferThresholdAssetsCashflowEarningPower",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "mack_PriorToDecemberThreeOneTwoZeroOneEightMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Prior to december three one two zero one eight.",
        "label": "Prior To December Three One Two Zero One Eight [Member]",
        "terseLabel": "Prior To December 31, 2018 [Member]"
       }
      }
     },
     "localname": "PriorToDecemberThreeOneTwoZeroOneEightMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_PriotToDecemberThreeOneTwoZeroOneNineMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Priot to december three one two zero one nine.",
        "label": "Priot To December Three One Two Zero One Nine [Member]",
        "terseLabel": "Prior To December 31, 2019 [Member]"
       }
      }
     },
     "localname": "PriotToDecemberThreeOneTwoZeroOneNineMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_ProceedsFromSaleOfInProcessResearchAndDevelopmentAsset": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10100.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Proceeds from sale of in progress research and development asset.",
        "label": "Proceeds From Sale Of In Process Research And Development Asset",
        "terseLabel": "Proceeds from sale of in-process research and development asset"
       }
      }
     },
     "localname": "ProceedsFromSaleOfInProcessResearchAndDevelopmentAsset",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_PurchasePriceDescription": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Purchase price, description.",
        "label": "Purchase Price Description",
        "terseLabel": "Purchase price description"
       }
      }
     },
     "localname": "PurchasePriceDescription",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "mack_ReimbursementRevenues": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Repayment received or receivable for expenses incurred on behalf of a client or customer, other than those reimbursements received by landlords from tenants.",
        "label": "Reimbursement Revenues",
        "terseLabel": "Reimbursement of expenses"
       }
      }
     },
     "localname": "ReimbursementRevenues",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_RightsAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Rights Agreement [Member]",
        "label": "Rights Agreement [Member]",
        "terseLabel": "Stockholder Rights Agreement [Member]"
       }
      }
     },
     "localname": "RightsAgreementMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_ScheduleOfEmployeeAndNonemployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of employee and nonemployee service share based compensation allocation of recognized period costs.",
        "label": "Schedule Of Employee And Nonemployee Service Share Based Compensation Allocation Of Recognized Period Costs Table [Text Block]",
        "terseLabel": "Schedule of Recognized Stock-Based Compensation Expense"
       }
      }
     },
     "localname": "ScheduleOfEmployeeAndNonemployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTableTextBlock",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "mack_SeptemberSpecialDividendMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "September special dividend.",
        "label": "September Special Dividend [Member]",
        "terseLabel": "September Special Dividend [Member]"
       }
      }
     },
     "localname": "SeptemberSpecialDividendMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_SeriesZPreferredStockAndTheNumberOfSharesConstitutingSuchSeriesShares": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Series Z Preferred Stock\" and the number of shares constituting such series shares.",
        "label": "Series Z Preferred Stock And The Number Of Shares Constituting Such Series Shares",
        "terseLabel": "Number of shares constituting such series shares"
       }
      }
     },
     "localname": "SeriesZPreferredStockAndTheNumberOfSharesConstitutingSuchSeriesShares",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "sharesItemType"
    },
    "mack_SeriesZPreferredStockMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Series z preferred stock.",
        "label": "Series Z Preferred Stock [Member]",
        "terseLabel": "Series Z Junior Preferred Stock [Member]"
       }
      }
     },
     "localname": "SeriesZPreferredStockMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_SilverCreekPharmaceuticalsIncMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Subsidiary of the Company.",
        "label": "Silver Creek Pharmaceuticals Inc [Member]",
        "terseLabel": "Silver Creek Pharmaceuticals, Inc. [Member]"
       }
      }
     },
     "localname": "SilverCreekPharmaceuticalsIncMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_StockIncentivePlan2011Member": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Detail of the plan under which options are granted.",
        "label": "Stock Incentive Plan2011 [Member]",
        "terseLabel": "Stock Incentive Plan 2011 [Member]"
       }
      }
     },
     "localname": "StockIncentivePlan2011Member",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_SubleaseAgreementMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sublease agreement.",
        "label": "Sublease Agreement [Member]",
        "terseLabel": "Sublease Agreement [Member]"
       }
      }
     },
     "localname": "SubleaseAgreementMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_SummaryOfSignificantAccountingPoliciesLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Summary of significant accounting policies.",
        "label": "Summary Of Significant Accounting Policies [Line Items]",
        "terseLabel": "Summary Of Significant Accounting Policies [Line Items]"
       }
      }
     },
     "localname": "SummaryOfSignificantAccountingPoliciesLineItems",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "mack_SummaryOfSignificantAccountingPoliciesTable": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Summary of significant accounting policies.",
        "label": "Summary Of Significant Accounting Policies [Table]",
        "terseLabel": "Summary Of Significant Accounting Policies [Table]"
       }
      }
     },
     "localname": "SummaryOfSignificantAccountingPoliciesTable",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "mack_TaxCreditCarryforwardExpirationEndYear": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tax credit carryforward, expiration end year.",
        "label": "Tax Credit Carryforward Expiration End Year",
        "terseLabel": "Tax credit carryforwards expire year through"
       }
      }
     },
     "localname": "TaxCreditCarryforwardExpirationEndYear",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "gYearItemType"
    },
    "mack_TaxCreditCarryforwardExpirationStartYear": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tax credit carryforward, expiration start year.",
        "label": "Tax Credit Carryforward Expiration Start Year",
        "terseLabel": "Tax credit carryforwards expire year begin"
       }
      }
     },
     "localname": "TaxCreditCarryforwardExpirationStartYear",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "gYearItemType"
    },
    "mack_TermLoanMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Term loan.",
        "label": "Term Loan [Member]",
        "terseLabel": "Term Loan [Member]"
       }
      }
     },
     "localname": "TermLoanMember",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "mack_TransactionExpenses": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Transaction expenses.",
        "label": "Transaction Expenses",
        "terseLabel": "Transaction expenses"
       }
      }
     },
     "localname": "TransactionExpenses",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_UpfrontCashPaymentReceived": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Upfront cash payment received.",
        "label": "Upfront Cash Payment Received",
        "terseLabel": "Upfront cash payment received"
       }
      }
     },
     "localname": "UpfrontCashPaymentReceived",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_ValuationAllowanceDeferredTaxAssetAdditions": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The amount of the additions in the period in the valuation allowance for a specified deferred tax asset.",
        "label": "Valuation Allowance Deferred Tax Asset Additions",
        "terseLabel": "Additions"
       }
      }
     },
     "localname": "ValuationAllowanceDeferredTaxAssetAdditions",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfChangesInValuationAllowanceDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "mack_ValuationAllowanceDeferredTaxAssetDeductions": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The amount of the deductions in the period in the valuation allowance for deferred tax assets.",
        "label": "Valuation Allowance Deferred Tax Asset Deductions",
        "negatedLabel": "Deductions"
       }
      }
     },
     "localname": "ValuationAllowanceDeferredTaxAssetDeductions",
     "nsuri": "http://www.merrimackpharma.com/20201231",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfChangesInValuationAllowanceDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "srt_CounterpartyNameAxis": {
     "auth_ref": [
      "r52",
      "r102"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Counterparty Name [Axis]",
        "terseLabel": "Counterparty Name"
       }
      }
     },
     "localname": "CounterpartyNameAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_MaximumMember": {
     "auth_ref": [
      "r231",
      "r234",
      "r360",
      "r361",
      "r362",
      "r363",
      "r364",
      "r365",
      "r366",
      "r389",
      "r390"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Maximum [Member]",
        "terseLabel": "Maximum [Member]"
       }
      }
     },
     "localname": "MaximumMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_MinimumMember": {
     "auth_ref": [
      "r231",
      "r234",
      "r360",
      "r361",
      "r362",
      "r363",
      "r364",
      "r365",
      "r366",
      "r389",
      "r390"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Minimum [Member]",
        "terseLabel": "Minimum [Member]"
       }
      }
     },
     "localname": "MinimumMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RangeAxis": {
     "auth_ref": [
      "r221",
      "r231",
      "r234",
      "r360",
      "r361",
      "r362",
      "r363",
      "r364",
      "r365",
      "r366",
      "r389",
      "r390"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Range [Axis]",
        "terseLabel": "Statistical Measurement"
       }
      }
     },
     "localname": "RangeAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_RangeMember": {
     "auth_ref": [
      "r221",
      "r231",
      "r234",
      "r360",
      "r361",
      "r362",
      "r363",
      "r364",
      "r365",
      "r366",
      "r389",
      "r390"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Range [Member]",
        "terseLabel": "Statistical Measurement"
       }
      }
     },
     "localname": "RangeMember",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_RepurchaseAgreementCounterpartyNameDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Repurchase Agreement Counterparty Name [Domain]",
        "terseLabel": "Counterparty Name"
       }
      }
     },
     "localname": "RepurchaseAgreementCounterpartyNameDomain",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_ScenarioUnspecifiedDomain": {
     "auth_ref": [
      "r232"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Scenario Unspecified [Domain]",
        "terseLabel": "Scenario"
       }
      }
     },
     "localname": "ScenarioUnspecifiedDomain",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "srt_StatementScenarioAxis": {
     "auth_ref": [
      "r197",
      "r232",
      "r356"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement Scenario [Axis]",
        "terseLabel": "Scenario"
       }
      }
     },
     "localname": "StatementScenarioAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_TitleOfIndividualAxis": {
     "auth_ref": [
      "r170",
      "r355"
     ],
     "lang": {
      "en-us": {
       "role": {
        "label": "Title Of Individual [Axis]",
        "terseLabel": "Title of Individual"
       }
      }
     },
     "localname": "TitleOfIndividualAxis",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "srt_TitleOfIndividualWithRelationshipToEntityDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Title Of Individual With Relationship To Entity [Domain]",
        "terseLabel": "Title of Individual"
       }
      }
     },
     "localname": "TitleOfIndividualWithRelationshipToEntityDomain",
     "nsuri": "http://fasb.org/srt/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AccountingPoliciesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Accounting Policies [Abstract]"
       }
      }
     },
     "localname": "AccountingPoliciesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent": {
     "auth_ref": [
      "r43"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10090.0,
       "parentTag": "us-gaap_LiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.",
        "label": "Accounts Payable And Accrued Liabilities Current",
        "terseLabel": "Accounts payable, accrued expenses and other",
        "totalLabel": "Total accounts payable, accrued expenses and other"
       }
      }
     },
     "localname": "AccountsPayableAndAccruedLiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock": {
     "auth_ref": [
      "r42"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for accounts payable and accrued liabilities at the end of the reporting period.",
        "label": "Accounts Payable And Accrued Liabilities Disclosure [Text Block]",
        "terseLabel": "Accounts Payable, Accrued Expenses and Other"
       }
      }
     },
     "localname": "AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOther"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_AccountsPayableCurrent": {
     "auth_ref": [
      "r41"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail": {
       "order": 10010.0,
       "parentTag": "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent",
       "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccruedLiabilitiesCurrent": {
     "auth_ref": [
      "r45"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail": {
       "order": 10020.0,
       "parentTag": "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent",
       "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 goods and services"
       }
      }
     },
     "localname": "AccruedLiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AccumulatedOtherComprehensiveIncomeMember": {
     "auth_ref": [
      "r53",
      "r54",
      "r55",
      "r105",
      "r106",
      "r107",
      "r320",
      "r391",
      "r392"
     ],
     "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": "Accumulated Other Comprehensive Income [Member]",
        "terseLabel": "Accumulated Other Comprehensive Loss [Member]"
       }
      }
     },
     "localname": "AccumulatedOtherComprehensiveIncomeMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdditionalPaidInCapitalCommonStock": {
     "auth_ref": [
      "r30"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10060.0,
       "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AdditionalPaidInCapitalMember": {
     "auth_ref": [
      "r105",
      "r106",
      "r107",
      "r267",
      "r268",
      "r269"
     ],
     "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 [Member]"
       }
      }
     },
     "localname": "AdditionalPaidInCapitalMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings": {
     "auth_ref": [
      "r207",
      "r215"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of decrease in additional paid in capital (APIC) resulting from dividends legally declared (or paid) in excess of retained earnings balance.",
        "label": "Adjustments To Additional Paid In Capital Dividends In Excess Of Retained Earnings",
        "negatedLabel": "Dividends paid"
       }
      }
     },
     "localname": "AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue": {
     "auth_ref": [
      "r236",
      "r238",
      "r273",
      "r274"
     ],
     "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": "Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value",
        "terseLabel": "Stock-based compensation"
       }
      }
     },
     "localname": "AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AllocatedShareBasedCompensationExpense": {
     "auth_ref": [
      "r238",
      "r262",
      "r272"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail": {
       "order": 10010.0,
       "parentTag": "mack_AllocatedShareBasedCompensationExpenseIncludingNonEmployees",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.",
        "label": "Allocated Share Based Compensation Expense",
        "terseLabel": "Stock-based compensation expense for employee awards"
       }
      }
     },
     "localname": "AllocatedShareBasedCompensationExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount": {
     "auth_ref": [
      "r125"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.",
        "label": "Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount",
        "terseLabel": "Outstanding options to purchase common stock"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfSecuritiesExcludedFromComputationOfDilutedLossPerShareDetail"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis": {
     "auth_ref": [
      "r125"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of antidilutive security.",
        "label": "Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis]",
        "terseLabel": "Antidilutive Securities"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfSecuritiesExcludedFromComputationOfDilutedLossPerShareDetail"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfSecuritiesExcludedFromComputationOfDilutedLossPerShareDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AntidilutiveSecuritiesNameDomain": {
     "auth_ref": [
      "r125"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Incremental common shares attributable to securities that were not included in diluted earnings per share (EPS) because to do so would increase EPS amounts or decrease loss per share amounts for the period presented.",
        "label": "Antidilutive Securities Name [Domain]",
        "terseLabel": "Antidilutive Securities, Name"
       }
      }
     },
     "localname": "AntidilutiveSecuritiesNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfSecuritiesExcludedFromComputationOfDilutedLossPerShareDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ArrangementsAndNonarrangementTransactionsMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Collaborative arrangement and arrangement other than collaborative applicable to revenue-generating activity or operations.",
        "label": "Arrangements And Nonarrangement Transactions [Member]",
        "terseLabel": "Collaborative Arrangement and Arrangement Other than Collaborative"
       }
      }
     },
     "localname": "ArrangementsAndNonarrangementTransactionsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_Assets": {
     "auth_ref": [
      "r100",
      "r149",
      "r159",
      "r165",
      "r173",
      "r315",
      "r322",
      "r341",
      "r370",
      "r380"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_AssetsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Assets [Abstract]",
        "terseLabel": "Assets"
       }
      }
     },
     "localname": "AssetsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AssetsCurrent": {
     "auth_ref": [
      "r20",
      "r21",
      "r51",
      "r100",
      "r173",
      "r315",
      "r322",
      "r341"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10110.0,
       "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_AwardTypeAxis": {
     "auth_ref": [
      "r239",
      "r265"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of award under share-based payment arrangement.",
        "label": "Award Type [Axis]",
        "terseLabel": "Award Type"
       }
      }
     },
     "localname": "AwardTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CashAndCashEquivalentsAtCarryingValue": {
     "auth_ref": [
      "r19",
      "r37",
      "r92"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10130.0,
       "parentTag": "us-gaap_AssetsCurrent",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.",
        "label": "Cash And Cash Equivalents At Carrying Value",
        "terseLabel": "Cash and cash equivalents"
       }
      }
     },
     "localname": "CashAndCashEquivalentsAtCarryingValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsFairValueDisclosure": {
     "auth_ref": [],
     "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 equivalents"
       }
      }
     },
     "localname": "CashAndCashEquivalentsFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy": {
     "auth_ref": [
      "r25",
      "r93",
      "r97",
      "r369"
     ],
     "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",
        "terseLabel": "Cash and Cash Equivalents"
       }
      }
     },
     "localname": "CashAndCashEquivalentsRestrictedCashAndCashEquivalentsPolicy",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CashCashEquivalentsAndShortTermInvestments": {
     "auth_ref": [
      "r37"
     ],
     "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 marketable securities"
       }
      }
     },
     "localname": "CashCashEquivalentsAndShortTermInvestments",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents": {
     "auth_ref": [
      "r86",
      "r92",
      "r96"
     ],
     "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 and cash equivalents, end of period",
        "periodStartLabel": "Cash, cash equivalents and restricted cash, beginning of period"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect": {
     "auth_ref": [
      "r86",
      "r342"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "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 in cash, cash equivalents and restricted cash"
       }
      }
     },
     "localname": "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ClassOfStockDomain": {
     "auth_ref": [
      "r98",
      "r100",
      "r118",
      "r119",
      "r120",
      "r122",
      "r124",
      "r130",
      "r131",
      "r132",
      "r173",
      "r341"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Share of stock differentiated by the voting rights the holder receives. Examples include, but are not limited to, common stock, redeemable preferred stock, nonredeemable preferred stock, and convertible stock.",
        "label": "Class Of Stock [Domain]",
        "terseLabel": "Class of Stock"
       }
      }
     },
     "localname": "ClassOfStockDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ClassOfStockLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Class Of Stock [Line Items]",
        "terseLabel": "Class Of Stock [Line Items]"
       }
      }
     },
     "localname": "ClassOfStockLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1": {
     "auth_ref": [
      "r208"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Exercise price per share or per unit of warrants or rights outstanding.",
        "label": "Class Of Warrant Or Right Exercise Price Of Warrants Or Rights1",
        "terseLabel": "Preferred stock purchase price"
       }
      }
     },
     "localname": "ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CollaborativeArrangementDisclosureTextBlock": {
     "auth_ref": [
      "r309",
      "r310",
      "r312"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for collaborative arrangements in which the entity is a participant, including a) information about the nature and purpose of such arrangements; b) its rights and obligations thereunder; c) the accounting policy for collaborative arrangements; and d) the income statement classification and amounts attributable to transactions arising from the collaborative arrangement between participants.",
        "label": "Collaborative Arrangement Disclosure [Text Block]",
        "terseLabel": "License and Collaboration Agreements"
       }
      }
     },
     "localname": "CollaborativeArrangementDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreements"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.",
        "label": "Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]",
        "terseLabel": "Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]"
       }
      }
     },
     "localname": "CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_CommitmentsAndContingencies": {
     "auth_ref": [
      "r48",
      "r196",
      "r372",
      "r383"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10020.0,
       "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 (Note 13)"
       }
      }
     },
     "localname": "CommitmentsAndContingencies",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Commitments And Contingencies Disclosure [Abstract]"
       }
      }
     },
     "localname": "CommitmentsAndContingenciesDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_CommitmentsAndContingenciesDisclosureTextBlock": {
     "auth_ref": [
      "r193",
      "r194",
      "r195",
      "r198"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingencies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CommonStockDividendsPerShareCashPaid": {
     "auth_ref": [
      "r215"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Aggregate dividends paid during the period for each share of common stock outstanding.",
        "label": "Common Stock Dividends Per Share Cash Paid",
        "terseLabel": "Cash dividends paid per common share"
       }
      }
     },
     "localname": "CommonStockDividendsPerShareCashPaid",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CommonStockMember": {
     "auth_ref": [
      "r105",
      "r106"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Stock that is subordinate to all other stock of the issuer.",
        "label": "Common Stock [Member]",
        "terseLabel": "Common Stock [Member]"
       }
      }
     },
     "localname": "CommonStockMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_CommonStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r29"
     ],
     "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"
       }
      }
     },
     "localname": "CommonStockParOrStatedValuePerShare",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_CommonStockSharesAuthorized": {
     "auth_ref": [
      "r29"
     ],
     "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"
       }
      }
     },
     "localname": "CommonStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesIssued": {
     "auth_ref": [
      "r29"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.",
        "label": "Common Stock Shares Issued",
        "terseLabel": "Common stock, shares issued"
       }
      }
     },
     "localname": "CommonStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockSharesOutstanding": {
     "auth_ref": [
      "r29",
      "r207"
     ],
     "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"
       }
      }
     },
     "localname": "CommonStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_CommonStockValue": {
     "auth_ref": [
      "r29"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10050.0,
       "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",
        "terseLabel": "Common stock, $0.01 par value: 30,000 shares authorized at December 31, 2020 and 2019; 13,380 shares issued and outstanding at December 31, 2020 and 2019"
       }
      }
     },
     "localname": "CommonStockValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_CompensationAndEmployeeBenefitPlansTextBlock": {
     "auth_ref": [
      "r219",
      "r220",
      "r235",
      "r275"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for an entity's employee compensation and benefit plans, including, but not limited to, postemployment and postretirement benefit plans, defined benefit pension plans, defined contribution plans, non-qualified and supplemental benefit plans, deferred compensation, share-based compensation, life insurance, severance, health care, unemployment and other benefit plans.",
        "label": "Compensation And Employee Benefit Plans [Text Block]",
        "terseLabel": "Retirement Plan"
       }
      }
     },
     "localname": "CompensationAndEmployeeBenefitPlansTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRetirementPlan"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_CompensationAndRetirementDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Compensation And Retirement Disclosure [Abstract]"
       }
      }
     },
     "localname": "CompensationAndRetirementDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Components Of Deferred Tax Assets And Liabilities [Abstract]"
       }
      }
     },
     "localname": "ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_ComprehensiveIncomeNetOfTax": {
     "auth_ref": [
      "r58",
      "r60",
      "r61",
      "r67",
      "r375",
      "r386"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "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 Net Of Tax",
        "totalLabel": "Comprehensive loss"
       }
      }
     },
     "localname": "ComprehensiveIncomeNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ComprehensiveIncomePolicyPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for comprehensive income.",
        "label": "Comprehensive Income Policy Policy [Text Block]",
        "terseLabel": "Comprehensive Loss"
       }
      }
     },
     "localname": "ComprehensiveIncomePolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ConcentrationRiskCreditRisk": {
     "auth_ref": [
      "r135",
      "r379"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for credit risk.",
        "label": "Concentration Risk Credit Risk",
        "terseLabel": "Concentration of Credit Risk"
       }
      }
     },
     "localname": "ConcentrationRiskCreditRisk",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems": {
     "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": "Consolidation Less Than Wholly Owned Subsidiary Parent Ownership Interest Effects Of Changes Net [Line Items]",
        "terseLabel": "Consolidation Less Than Wholly Owned Subsidiary Parent Ownership Interest Effects Of Changes Net [Line Items]"
       }
      }
     },
     "localname": "ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable": {
     "auth_ref": [
      "r321",
      "r326"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Summarization of information required and determined to be disclosed concerning the effects of any changes in a parent's ownership interest in a subsidiary on the equity attributable to the parent which may have occurred during the period. The changes represented by this element did not result in the deconsolidation of the subsidiary.",
        "label": "Consolidation Less Than Wholly Owned Subsidiary Parent Ownership Interest Effects Of Changes Net [Table]",
        "terseLabel": "Consolidation Less Than Wholly Owned Subsidiary Parent Ownership Interest Effects Of Changes Net [Table]"
       }
      }
     },
     "localname": "ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Debt Disclosure [Abstract]"
       }
      }
     },
     "localname": "DebtDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtDisclosureTextBlock": {
     "auth_ref": [
      "r202"
     ],
     "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": "Borrowings"
       }
      }
     },
     "localname": "DebtDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowings"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DebtInstrumentFaceAmount": {
     "auth_ref": [
      "r351",
      "r353"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Face (par) amount of debt instrument at time of issuance.",
        "label": "Debt Instrument Face Amount",
        "terseLabel": "Aggregate principal amount of loan"
       }
      }
     },
     "localname": "DebtInstrumentFaceAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DebtInstrumentLineItems": {
     "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": "Debt Instrument [Line Items]",
        "terseLabel": "Debt Instrument [Line Items]"
       }
      }
     },
     "localname": "DebtInstrumentLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DebtInstrumentTable": {
     "auth_ref": [
      "r47",
      "r103",
      "r208",
      "r212",
      "r213",
      "r214",
      "r350",
      "r351",
      "r353",
      "r378"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "A table or schedule providing information pertaining to long-term debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the company, if longer.",
        "label": "Debt Instrument [Table]",
        "terseLabel": "Debt Instrument [Table]"
       }
      }
     },
     "localname": "DebtInstrumentTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DeferredCreditsAndOtherLiabilitiesCurrent": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail": {
       "order": 10060.0,
       "parentTag": "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Carrying amount as of the balance sheet date of unearned revenue or income, not otherwise specified in the taxonomy, which is expected to be taken into income during the current period and current obligations not separately disclosed in the balance sheet (other liabilities, current).",
        "label": "Deferred Credits And Other Liabilities Current",
        "terseLabel": "Deferred tax incentives"
       }
      }
     },
     "localname": "DeferredCreditsAndOtherLiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredRevenueArrangementTypeAxis": {
     "auth_ref": [
      "r24"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of deferred revenue arrangement.",
        "label": "Deferred Revenue Arrangement Type [Axis]",
        "terseLabel": "Deferred Revenue Arrangement Type"
       }
      }
     },
     "localname": "DeferredRevenueArrangementTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DeferredRevenueArrangementTypeDomain": {
     "auth_ref": [
      "r24"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Category of obligation arising when an entity receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized.",
        "label": "Deferred Revenue Arrangement Type [Domain]",
        "terseLabel": "Deferred Revenue"
       }
      }
     },
     "localname": "DeferredRevenueArrangementTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DeferredTaxAssetsGross": {
     "auth_ref": [
      "r286"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.",
        "label": "Deferred Tax Assets Gross",
        "totalLabel": "Total gross deferred tax assets"
       }
      }
     },
     "localname": "DeferredTaxAssetsGross",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredTaxAssetsGrossAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Deferred Tax Assets Gross [Abstract]",
        "terseLabel": "Deferred tax assets"
       }
      }
     },
     "localname": "DeferredTaxAssetsGrossAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DeferredTaxAssetsOperatingLossCarryforwards": {
     "auth_ref": [
      "r293",
      "r294"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": 10010.0,
       "parentTag": "us-gaap_DeferredTaxAssetsGross",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.",
        "label": "Deferred Tax Assets Operating Loss Carryforwards",
        "terseLabel": "Net operating losses"
       }
      }
     },
     "localname": "DeferredTaxAssetsOperatingLossCarryforwards",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredTaxAssetsOther": {
     "auth_ref": [
      "r293",
      "r294"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": 10070.0,
       "parentTag": "us-gaap_DeferredTaxAssetsGross",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.",
        "label": "Deferred Tax Assets Other",
        "terseLabel": "Other temporary differences"
       }
      }
     },
     "localname": "DeferredTaxAssetsOther",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredTaxAssetsTaxCreditCarryforwards": {
     "auth_ref": [
      "r291",
      "r293",
      "r294"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": 10030.0,
       "parentTag": "us-gaap_DeferredTaxAssetsGross",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount, before allocation of a valuation allowances, of deferred tax assets attributable to deductible tax credit carryforwards including, but not limited to, research, foreign, general business, alternative minimum tax, and other deductible tax credit carryforwards.",
        "label": "Deferred Tax Assets Tax Credit Carryforwards",
        "terseLabel": "Credit carryforwards"
       }
      }
     },
     "localname": "DeferredTaxAssetsTaxCreditCarryforwards",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost": {
     "auth_ref": [
      "r293",
      "r294"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": 10040.0,
       "parentTag": "us-gaap_DeferredTaxAssetsGross",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.",
        "label": "Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost",
        "terseLabel": "Deferred compensation"
       }
      }
     },
     "localname": "DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals": {
     "auth_ref": [
      "r293",
      "r294"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail": {
       "order": 10060.0,
       "parentTag": "us-gaap_DeferredTaxAssetsGross",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from reserves and accruals.",
        "label": "Deferred Tax Assets Tax Deferred Expense Reserves And Accruals",
        "terseLabel": "Accrued expenses"
       }
      }
     },
     "localname": "DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DeferredTaxAssetsValuationAllowance": {
     "auth_ref": [
      "r287"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.",
        "label": "Deferred Tax Assets Valuation Allowance",
        "negatedLabel": "Valuation allowance",
        "periodEndLabel": "Balance at end of period",
        "periodStartLabel": "Balance at beginning of period"
       }
      }
     },
     "localname": "DeferredTaxAssetsValuationAllowance",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfChangesInValuationAllowanceDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfTemporaryDifferencesThatGiveRiseToSignificantNetDeferredTaxAssetsDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of discretionary contributions made by an employer to a defined contribution plan.",
        "label": "Defined Contribution Plan Employer Discretionary Contribution Amount",
        "terseLabel": "Company's contributions to 401(k) defined contribution savings plan"
       }
      }
     },
     "localname": "DefinedContributionPlanEmployerDiscretionaryContributionAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRetirementPlanAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DepreciationDepletionAndAmortization": {
     "auth_ref": [
      "r90",
      "r147"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10210.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.",
        "label": "Depreciation Depletion And Amortization",
        "terseLabel": "Depreciation and amortization expense"
       }
      }
     },
     "localname": "DepreciationDepletionAndAmortization",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock": {
     "auth_ref": [
      "r275"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for share-based payment arrangement.",
        "label": "Disclosure Of Compensation Related Costs Share Based Payments [Text Block]",
        "terseLabel": "Stock-Based Compensation"
       }
      }
     },
     "localname": "DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensation"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]"
       }
      }
     },
     "localname": "DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax": {
     "auth_ref": [
      "r1",
      "r3",
      "r5"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail": {
       "order": 10030.0,
       "parentTag": "us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount before tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.",
        "label": "Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Tax",
        "terseLabel": "Discontinued operations, amounts directly relate to commercial bussiness",
        "verboseLabel": "Gain on sale of Commercial Business"
       }
      }
     },
     "localname": "DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax": {
     "auth_ref": [
      "r1",
      "r2",
      "r3",
      "r4",
      "r5",
      "r12",
      "r65",
      "r384"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail": {
       "order": 10010.0,
       "parentTag": "us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount before tax of income (loss) from a discontinued operation. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.",
        "label": "Discontinued Operation Income Loss From Discontinued Operation Before Income Tax",
        "totalLabel": "Income from discontinued operations"
       }
      }
     },
     "localname": "DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation": {
     "auth_ref": [
      "r2",
      "r3",
      "r4",
      "r5",
      "r12",
      "r14",
      "r280",
      "r299",
      "r303"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail": {
       "order": 10020.0,
       "parentTag": "us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.",
        "label": "Discontinued Operation Tax Effect Of Discontinued Operation",
        "negatedLabel": "Income tax expense",
        "verboseLabel": "Discontinued operation tax effect of discontinued operation"
       }
      }
     },
     "localname": "DiscontinuedOperationTaxEffectOfDiscontinuedOperation",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Discontinued Operations And Disposal Groups [Abstract]"
       }
      }
     },
     "localname": "DiscontinuedOperationsAndDisposalGroupsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock": {
     "auth_ref": [
      "r18",
      "r180"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.",
        "label": "Disposal Groups Including Discontinued Operations Disclosure [Text Block]",
        "terseLabel": "Discontinued Operations - Sale of Commercial Business"
       }
      }
     },
     "localname": "DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusiness"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain": {
     "auth_ref": [
      "r230",
      "r233"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Name of disposal group.",
        "label": "Disposal Groups Including Discontinued Operations Name [Domain]",
        "terseLabel": "Disposal Group Name"
       }
      }
     },
     "localname": "DisposalGroupsIncludingDiscontinuedOperationsNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DividendPayableDateToBePaidDayMonthAndYear": {
     "auth_ref": [
      "r95"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Date the declared dividend will be paid, in CCYY-MM-DD format.",
        "label": "Dividend Payable Date To Be Paid Day Month And Year",
        "terseLabel": "Dividend payable date"
       }
      }
     },
     "localname": "DividendPayableDateToBePaidDayMonthAndYear",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "dateItemType"
    },
    "us-gaap_DividendsAxis": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information about distribution of earnings to shareholders including, but not limited to, cash, property or capital stock.",
        "label": "Dividends [Axis]",
        "terseLabel": "Dividends"
       }
      }
     },
     "localname": "DividendsAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_DividendsCommonStockCash": {
     "auth_ref": [
      "r215"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.",
        "label": "Dividends Common Stock Cash",
        "terseLabel": "Special cash dividend paid"
       }
      }
     },
     "localname": "DividendsCommonStockCash",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_DividendsDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Distributions of earnings to shareholders including but not limited to cash, property or capital stock.",
        "label": "Dividends [Domain]",
        "terseLabel": "Dividends"
       }
      }
     },
     "localname": "DividendsDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_DividendsPayableDateOfRecordDayMonthAndYear": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.",
        "label": "Dividends Payable Date Of Record Day Month And Year",
        "terseLabel": "Dividend payable, date of record"
       }
      }
     },
     "localname": "DividendsPayableDateOfRecordDayMonthAndYear",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "dateItemType"
    },
    "us-gaap_EarningsPerShareAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Earnings Per Share [Abstract]"
       }
      }
     },
     "localname": "EarningsPerShareAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_EarningsPerShareBasicAndDiluted": {
     "auth_ref": [
      "r123"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "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",
        "totalLabel": "Net loss per share"
       }
      }
     },
     "localname": "EarningsPerShareBasicAndDiluted",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_EarningsPerShareBasicAndDilutedAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Earnings Per Share Basic And Diluted [Abstract]",
        "terseLabel": "Basic and dilutive net loss per common share"
       }
      }
     },
     "localname": "EarningsPerShareBasicAndDilutedAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EarningsPerSharePolicyTextBlock": {
     "auth_ref": [
      "r97",
      "r125",
      "r126"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for computing basic and diluted earnings or loss per share for each class of common stock and participating security. Addresses all significant policy factors, including any antidilutive items that have been excluded from the computation and takes into account stock dividends, splits and reverse splits that occur after the balance sheet date of the latest reporting period but before the issuance of the financial statements.",
        "label": "Earnings Per Share Policy [Text Block]",
        "terseLabel": "Net Loss Per Common Share"
       }
      }
     },
     "localname": "EarningsPerSharePolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_EarningsPerShareTextBlock": {
     "auth_ref": [
      "r125",
      "r126",
      "r127",
      "r128"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for earnings per share.",
        "label": "Earnings Per Share [Text Block]",
        "terseLabel": "Net Loss Per Common Share"
       }
      }
     },
     "localname": "EarningsPerShareTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShare"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_EffectiveIncomeTaxRateContinuingOperations": {
     "auth_ref": [
      "r281"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.",
        "label": "Effective Income Tax Rate Continuing Operations",
        "totalLabel": "Total"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateContinuingOperations",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate": {
     "auth_ref": [
      "r281",
      "r300"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": 10010.0,
       "parentTag": "us-gaap_EffectiveIncomeTaxRateContinuingOperations",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Percentage of domestic federal statutory tax rate applicable to pretax income (loss).",
        "label": "Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate",
        "verboseLabel": "Federal income tax at statutory federal rate"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance": {
     "auth_ref": [
      "r281",
      "r300"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": 10080.0,
       "parentTag": "us-gaap_EffectiveIncomeTaxRateContinuingOperations",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.",
        "label": "Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance",
        "terseLabel": "Change in valuation allowance"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense": {
     "auth_ref": [
      "r281",
      "r300"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": 10030.0,
       "parentTag": "us-gaap_EffectiveIncomeTaxRateContinuingOperations",
       "weight": -1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to nondeductible expenses.",
        "label": "Effective Income Tax Rate Reconciliation Nondeductible Expense",
        "negatedLabel": "Permanent differences"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateReconciliationNondeductibleExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments": {
     "auth_ref": [
      "r281",
      "r300"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": 10070.0,
       "parentTag": "us-gaap_EffectiveIncomeTaxRateContinuingOperations",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to other adjustments.",
        "label": "Effective Income Tax Rate Reconciliation Other Adjustments",
        "terseLabel": "Other"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateReconciliationOtherAdjustments",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes": {
     "auth_ref": [
      "r281",
      "r300"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": 10020.0,
       "parentTag": "us-gaap_EffectiveIncomeTaxRateContinuingOperations",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).",
        "label": "Effective Income Tax Rate Reconciliation State And Local Income Taxes",
        "terseLabel": "State taxes"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_EffectiveIncomeTaxRateReconciliationTaxCredits": {
     "auth_ref": [
      "r281",
      "r300"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail": {
       "order": 10040.0,
       "parentTag": "us-gaap_EffectiveIncomeTaxRateContinuingOperations",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.",
        "label": "Effective Income Tax Rate Reconciliation Tax Credits",
        "terseLabel": "Tax credits"
       }
      }
     },
     "localname": "EffectiveIncomeTaxRateReconciliationTaxCredits",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfCompanySEffectiveTaxRateToStatutoryFederalIncomeTaxRateDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "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": "Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]",
        "terseLabel": "Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1": {
     "auth_ref": [
      "r264"
     ],
     "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": "Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1",
        "terseLabel": "Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions": {
     "auth_ref": [
      "r264"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cost to be recognized for option under share-based payment arrangement.",
        "label": "Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options",
        "terseLabel": "Unrecognized stock-based compensation expense related to nonvested stock options"
       }
      }
     },
     "localname": "EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EmployeeSeveranceMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Termination of an employee associated with exit from or disposal of business activities or restructurings pursuant to a plan.",
        "label": "Employee Severance [Member]",
        "terseLabel": "Severance Benefits and Related Costs Due to Workforce Reduction [Member]"
       }
      }
     },
     "localname": "EmployeeSeveranceMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EmployeeStockOptionMember": {
     "auth_ref": [
      "r260"
     ],
     "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": "Employee Stock Option [Member]",
        "terseLabel": "Options to Purchase Common Stock [Member]",
        "verboseLabel": "Stock Options [Member]"
       }
      }
     },
     "localname": "EmployeeStockOptionMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Equity [Abstract]"
       }
      }
     },
     "localname": "EquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_EquityComponentDomain": {
     "auth_ref": [
      "r105",
      "r106",
      "r107",
      "r109",
      "r114",
      "r116",
      "r129",
      "r174",
      "r207",
      "r215",
      "r267",
      "r268",
      "r269",
      "r296",
      "r297",
      "r343",
      "r344",
      "r345",
      "r346",
      "r347",
      "r348",
      "r391",
      "r392",
      "r393"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Components of equity are the parts of the total Equity balance including that which is allocated to common, preferred, treasury stock, retained earnings, etc.",
        "label": "Equity Component [Domain]",
        "terseLabel": "Equity Component"
       }
      }
     },
     "localname": "EquityComponentDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal": {
     "auth_ref": [
      "r69",
      "r70",
      "r90"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of gain (loss) on sale or disposal of an equity method investment.",
        "label": "Equity Method Investment Realized Gain Loss On Disposal",
        "terseLabel": "Equity method investment realized gain loss on sale"
       }
      }
     },
     "localname": "EquityMethodInvestmentRealizedGainLossOnDisposal",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_EquityMethodInvestments": {
     "auth_ref": [
      "r38",
      "r150",
      "r172"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.",
        "label": "Equity Method Investments",
        "terseLabel": "Equity method investment"
       }
      }
     },
     "localname": "EquityMethodInvestments",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable": {
     "auth_ref": [
      "r328",
      "r329",
      "r330",
      "r335"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about asset and liability measured at fair value on recurring and nonrecurring basis.",
        "label": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table]",
        "terseLabel": "Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table]"
       }
      }
     },
     "localname": "FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnRecurringBasisTextBlock": {
     "auth_ref": [
      "r328",
      "r329"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).",
        "label": "Fair Value Assets Measured On Recurring Basis [Text Block]",
        "terseLabel": "Summary of Assets Measured at Fair Value on a Recurring Basis"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnRecurringBasisTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain": {
     "auth_ref": [
      "r333"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Class of asset.",
        "label": "Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain]",
        "terseLabel": "Asset Class"
       }
      }
     },
     "localname": "FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems": {
     "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 Balance Sheet Grouping Financial Statement Captions [Line Items]",
        "terseLabel": "Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]"
       }
      }
     },
     "localname": "FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByAssetClassAxis": {
     "auth_ref": [
      "r328",
      "r335"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by class of asset.",
        "label": "Fair Value By Asset Class [Axis]",
        "terseLabel": "Asset Class"
       }
      }
     },
     "localname": "FairValueByAssetClassAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByBalanceSheetGroupingTable": {
     "auth_ref": [
      "r328",
      "r339",
      "r340"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about the fair value of financial instruments, including financial assets and financial liabilities, and the measurements of those instruments, assets, and liabilities.",
        "label": "Fair Value By Balance Sheet Grouping [Table]",
        "terseLabel": "Fair Value By Balance Sheet Grouping [Table]"
       }
      }
     },
     "localname": "FairValueByBalanceSheetGroupingTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByFairValueHierarchyLevelAxis": {
     "auth_ref": [
      "r222",
      "r223",
      "r224",
      "r225",
      "r226",
      "r227",
      "r228",
      "r229",
      "r329",
      "r357",
      "r358",
      "r359"
     ],
     "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 By Fair Value Hierarchy Level [Axis]",
        "terseLabel": "Level 2 [Member]"
       }
      }
     },
     "localname": "FairValueByFairValueHierarchyLevelAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueByMeasurementFrequencyAxis": {
     "auth_ref": [
      "r328",
      "r329",
      "r331",
      "r332",
      "r336"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by measurement frequency.",
        "label": "Fair Value By Measurement Frequency [Axis]",
        "terseLabel": "Measurement Frequency"
       }
      }
     },
     "localname": "FairValueByMeasurementFrequencyAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosuresAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Fair Value Disclosures [Abstract]"
       }
      }
     },
     "localname": "FairValueDisclosuresAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_FairValueDisclosuresTextBlock": {
     "auth_ref": [
      "r334"
     ],
     "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 of Financial Instruments"
       }
      }
     },
     "localname": "FairValueDisclosuresTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstruments"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_FairValueInputsLevel1Member": {
     "auth_ref": [
      "r222",
      "r223",
      "r228",
      "r229",
      "r329",
      "r357"
     ],
     "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 Level1 [Member]",
        "terseLabel": "Level 1 [Member]"
       }
      }
     },
     "localname": "FairValueInputsLevel1Member",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel2Member": {
     "auth_ref": [
      "r222",
      "r223",
      "r228",
      "r229",
      "r329",
      "r358"
     ],
     "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 Level2 [Member]",
        "terseLabel": "Level 2 [Member]"
       }
      }
     },
     "localname": "FairValueInputsLevel2Member",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueInputsLevel3Member": {
     "auth_ref": [
      "r222",
      "r223",
      "r224",
      "r225",
      "r226",
      "r227",
      "r228",
      "r229",
      "r329",
      "r359"
     ],
     "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 Level3 [Member]",
        "terseLabel": "Level 3 [Member]"
       }
      }
     },
     "localname": "FairValueInputsLevel3Member",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementFrequencyDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Measurement frequency.",
        "label": "Fair Value Measurement Frequency [Domain]",
        "terseLabel": "Measurement Frequency"
       }
      }
     },
     "localname": "FairValueMeasurementFrequencyDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementsFairValueHierarchyDomain": {
     "auth_ref": [
      "r222",
      "r223",
      "r224",
      "r225",
      "r226",
      "r227",
      "r228",
      "r229",
      "r357",
      "r358",
      "r359"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Categories used to prioritize the inputs to valuation techniques to measure fair value.",
        "label": "Fair Value Measurements Fair Value Hierarchy [Domain]",
        "terseLabel": "Fair Value Hierarchy and NAV"
       }
      }
     },
     "localname": "FairValueMeasurementsFairValueHierarchyDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueMeasurementsRecurringMember": {
     "auth_ref": [
      "r334",
      "r336"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Frequent fair value measurement. Includes, but is not limited to, fair value adjustment for impairment of asset, liability or equity, frequently measured at fair value.",
        "label": "Fair Value Measurements Recurring [Member]",
        "terseLabel": "Recurring Basis [Member]"
       }
      }
     },
     "localname": "FairValueMeasurementsRecurringMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_FairValueOfFinancialInstrumentsPolicy": {
     "auth_ref": [
      "r97",
      "r337",
      "r338"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for determining the fair value of financial instruments.",
        "label": "Fair Value Of Financial Instruments Policy",
        "terseLabel": "Fair Value of Financial Instruments"
       }
      }
     },
     "localname": "FairValueOfFinancialInstrumentsPolicy",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_GainLossOnDispositionOfAssets1": {
     "auth_ref": [
      "r90"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10180.0,
       "parentTag": "us-gaap_OperatingExpenses",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.",
        "label": "Gain Loss On Disposition Of Assets1",
        "negatedLabel": "Gain on sale of assets"
       }
      }
     },
     "localname": "GainLossOnDispositionOfAssets1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainLossOnSaleOfEquityInvestments": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10230.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The difference between the carrying value and the sale price of equity securities, not separately or otherwise categorized as trading or available-for-sale. This element includes investments in which the entity holds a small ownership stake (generally, less than 20% of the shares outstanding) and cannot exert significant influence.",
        "label": "Gain Loss On Sale Of Equity Investments",
        "negatedLabel": "Gain on equity method investment",
        "terseLabel": "Loss on equity method investment"
       }
      }
     },
     "localname": "GainLossOnSaleOfEquityInvestments",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainLossOnSaleOfPropertyPlantEquipment": {
     "auth_ref": [
      "r90"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10190.0,
       "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 Sale Of Property Plant Equipment",
        "negatedLabel": "Gain on sale of property and equipment"
       }
      }
     },
     "localname": "GainLossOnSaleOfPropertyPlantEquipment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GainsLossesOnExtinguishmentOfDebt": {
     "auth_ref": [
      "r90",
      "r200",
      "r201"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10170.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.",
        "label": "Gains Losses On Extinguishment Of Debt",
        "negatedLabel": "Loss on extinguishment of debt",
        "terseLabel": "Loss on extinguishment of debt"
       }
      }
     },
     "localname": "GainsLossesOnExtinguishmentOfDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GeneralAndAdministrativeExpense": {
     "auth_ref": [
      "r71"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10170.0,
       "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 expenses"
       }
      }
     },
     "localname": "GeneralAndAdministrativeExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_GeneralAndAdministrativeExpenseMember": {
     "auth_ref": [
      "r68"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Primary financial statement caption encompassing general and administrative expense.",
        "label": "General And Administrative Expense [Member]",
        "terseLabel": "General and Administrative Expense [Member]",
        "verboseLabel": "General and Administrative Expense [Member]"
       }
      }
     },
     "localname": "GeneralAndAdministrativeExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest": {
     "auth_ref": [
      "r64",
      "r149",
      "r158",
      "r161",
      "r164",
      "r166",
      "r368",
      "r373",
      "r377",
      "r387"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10080.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.",
        "label": "Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest",
        "totalLabel": "Net loss from continuing operations before income tax benefit"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest": {
     "auth_ref": [
      "r100",
      "r108",
      "r149",
      "r158",
      "r161",
      "r164",
      "r166",
      "r173",
      "r313",
      "r341"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10270.0,
       "parentTag": "us-gaap_ProfitLoss",
       "weight": 1.0
      },
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10060.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount after tax of income (loss) from continuing operations including portion attributable to the noncontrolling interest.",
        "label": "Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest",
        "negatedLabel": "Net loss from continuing operations",
        "terseLabel": "Loss from continuing operations",
        "totalLabel": "Net loss from continuing operations"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeLossFromContinuingOperationsPerBasicAndDilutedShare": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10010.0,
       "parentTag": "us-gaap_EarningsPerShareBasicAndDiluted",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The amount of net income (loss) from continuing operations per each basic and diluted share of common stock or unit when the per share amount is the same for both basic and diluted shares.",
        "label": "Income Loss From Continuing Operations Per Basic And Diluted Share",
        "terseLabel": "Net loss from continuing operations"
       }
      }
     },
     "localname": "IncomeLossFromContinuingOperationsPerBasicAndDilutedShare",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax": {
     "auth_ref": [
      "r1",
      "r2",
      "r3",
      "r4",
      "r5",
      "r14",
      "r17",
      "r305",
      "r384"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail": {
       "order": null,
       "parentTag": null,
       "root": true,
       "weight": null
      },
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10260.0,
       "parentTag": "us-gaap_ProfitLoss",
       "weight": 1.0
      },
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10070.0,
       "parentTag": "us-gaap_NetIncomeLoss",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.",
        "label": "Income Loss From Discontinued Operations Net Of Tax",
        "terseLabel": "Income from discontinued operations, net of tax",
        "totalLabel": "Total income from discontinued operations",
        "verboseLabel": "Income from discontinued operations"
       }
      }
     },
     "localname": "IncomeLossFromDiscontinuedOperationsNetOfTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Income Loss From Discontinued Operations Net Of Tax [Abstract]",
        "terseLabel": "Discontinued operations:"
       }
      }
     },
     "localname": "IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShare": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10020.0,
       "parentTag": "us-gaap_EarningsPerShareBasicAndDiluted",
       "weight": 1.0
      }
     },
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Per basic and diluted share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation and gain (loss) from the disposal of the discontinued operation, when the per share amount is the same.",
        "label": "Income Loss From Discontinued Operations Net Of Tax Per Basic And Diluted Share",
        "terseLabel": "Net income from discontinued operations, net of tax"
       }
      }
     },
     "localname": "IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShare",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis": {
     "auth_ref": [
      "r230",
      "r233"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by name of disposal group.",
        "label": "Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Axis]",
        "terseLabel": "Disposal Group Name"
       }
      }
     },
     "localname": "IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems": {
     "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": "Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]",
        "terseLabel": "Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]"
       }
      }
     },
     "localname": "IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable": {
     "auth_ref": [
      "r0",
      "r6",
      "r7",
      "r8",
      "r9",
      "r10",
      "r11",
      "r13",
      "r15",
      "r16",
      "r17",
      "r178",
      "r179"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.",
        "label": "Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Table]",
        "terseLabel": "Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Table]"
       }
      }
     },
     "localname": "IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessScheduleOfDiscontinuedOperationsAndAssetsHeldForSaleDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeStatementLocationAxis": {
     "auth_ref": [
      "r177"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by location in the income statement.",
        "label": "Income Statement Location [Axis]",
        "terseLabel": "Income Statement Location"
       }
      }
     },
     "localname": "IncomeStatementLocationAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail"
     ],
     "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"
       }
      }
     },
     "localname": "IncomeStatementLocationDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncomeTaxAuthorityAxis": {
     "auth_ref": [
      "r283"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by tax jurisdiction.",
        "label": "Income Tax Authority [Axis]",
        "terseLabel": "Income Tax Authority"
       }
      }
     },
     "localname": "IncomeTaxAuthorityAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeTaxAuthorityDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Agency, division or body classification that levies income taxes, examines tax returns for compliance, or grants exemptions from or makes other decisions pertaining to income taxes.",
        "label": "Income Tax Authority [Domain]",
        "terseLabel": "Income Tax Authority"
       }
      }
     },
     "localname": "IncomeTaxAuthorityDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncomeTaxAuthorityNameAxis": {
     "auth_ref": [
      "r283"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by name of taxing authority.",
        "label": "Income Tax Authority Name [Axis]",
        "terseLabel": "Income Tax Authority, Name"
       }
      }
     },
     "localname": "IncomeTaxAuthorityNameAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeTaxAuthorityNameDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Named agency, division or body that levies income taxes, examines tax returns for compliance, or grants exemptions from or makes other decisions pertaining to income taxes.",
        "label": "Income Tax Authority Name [Domain]",
        "terseLabel": "Income Tax Authority, Name"
       }
      }
     },
     "localname": "IncomeTaxAuthorityNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_IncomeTaxDisclosureAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Income Tax Disclosure [Abstract]"
       }
      }
     },
     "localname": "IncomeTaxDisclosureAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncomeTaxDisclosureTextBlock": {
     "auth_ref": [
      "r282",
      "r284",
      "r290",
      "r298",
      "r301",
      "r306",
      "r307",
      "r308"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxes"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_IncomeTaxExpenseBenefit": {
     "auth_ref": [
      "r101",
      "r115",
      "r116",
      "r148",
      "r280",
      "r299",
      "r302",
      "r388"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10090.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest",
       "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 benefit (expense)"
       }
      }
     },
     "localname": "IncomeTaxExpenseBenefit",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeTaxExpenseBenefitIntraperiodTaxAllocation": {
     "auth_ref": [
      "r299",
      "r304"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10180.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of income tax expense (benefit) for continuing operations, discontinued operations, other comprehensive income, and items charged (credited) directly to shareholders' equity.",
        "label": "Income Tax Expense Benefit Intraperiod Tax Allocation",
        "terseLabel": "Benefit from intra-period tax allocation"
       }
      }
     },
     "localname": "IncomeTaxExpenseBenefitIntraperiodTaxAllocation",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncomeTaxPolicyTextBlock": {
     "auth_ref": [
      "r62",
      "r97",
      "r278",
      "r279",
      "r284",
      "r285",
      "r289",
      "r295",
      "r396"
     ],
     "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 [Text Block]",
        "terseLabel": "Income Taxes"
       }
      }
     },
     "localname": "IncomeTaxPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities": {
     "auth_ref": [
      "r89"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10250.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The increase (decrease) during the reporting period in the amounts payable to vendors for goods and services received and the amount of obligations and expenses incurred but not paid.",
        "label": "Increase Decrease In Accounts Payable And Accrued Liabilities",
        "terseLabel": "Accounts payable, accrued expenses and other"
       }
      }
     },
     "localname": "IncreaseDecreaseInAccountsPayableAndAccruedLiabilities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_IncreaseDecreaseInOperatingCapitalAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Increase Decrease In Operating Capital [Abstract]",
        "terseLabel": "Changes in operating assets and liabilities:"
       }
      }
     },
     "localname": "IncreaseDecreaseInOperatingCapitalAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets": {
     "auth_ref": [
      "r89"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10240.0,
       "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 Deferred Expense And Other Assets",
        "negatedLabel": "Prepaid expenses and other assets"
       }
      }
     },
     "localname": "IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestExpense": {
     "auth_ref": [
      "r63",
      "r146",
      "r349",
      "r352",
      "r376"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10130.0,
       "parentTag": "us-gaap_NonoperatingIncomeExpense",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of the cost of borrowed funds accounted for as interest expense.",
        "label": "Interest Expense",
        "negatedLabel": "Interest expense",
        "terseLabel": "Interest expense"
       }
      }
     },
     "localname": "InterestExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InterestPaidNet": {
     "auth_ref": [
      "r83",
      "r87",
      "r94"
     ],
     "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 Net",
        "terseLabel": "Cash paid for interest"
       }
      }
     },
     "localname": "InterestPaidNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_InternalRevenueServiceIRSMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Designated tax department of the United States of America government entitled to levy and collect income taxes from the entity.",
        "label": "Internal Revenue Service I R S [Member]",
        "terseLabel": "Federal [Member]"
       }
      }
     },
     "localname": "InternalRevenueServiceIRSMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InvestmentCreditMember": {
     "auth_ref": [
      "r292"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Investment tax credit carryforwards arising from certain qualifying capital expenditures including, but not limited to, rehabilitation, energy, advanced coal project and gasification project.",
        "label": "Investment Credit [Member]",
        "terseLabel": "Investment [Member]"
       }
      }
     },
     "localname": "InvestmentCreditMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_InvestmentIncomeInterest": {
     "auth_ref": [
      "r72",
      "r145"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10120.0,
       "parentTag": "us-gaap_NonoperatingIncomeExpense",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.",
        "label": "Investment Income Interest",
        "terseLabel": "Interest income"
       }
      }
     },
     "localname": "InvestmentIncomeInterest",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_Liabilities": {
     "auth_ref": [
      "r44",
      "r100",
      "r160",
      "r173",
      "r316",
      "r322",
      "r323",
      "r341"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10010.0,
       "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesAndStockholdersEquity": {
     "auth_ref": [
      "r34",
      "r100",
      "r173",
      "r341",
      "r371",
      "r382"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "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 Stockholders Equity",
        "totalLabel": "Total liabilities and stockholders\u2019 equity"
       }
      }
     },
     "localname": "LiabilitiesAndStockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LiabilitiesAndStockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Liabilities And Stockholders Equity [Abstract]",
        "terseLabel": "Liabilities and stockholders\u2019 equity"
       }
      }
     },
     "localname": "LiabilitiesAndStockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LiabilitiesCurrent": {
     "auth_ref": [
      "r46",
      "r100",
      "r173",
      "r316",
      "r322",
      "r323",
      "r341"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10080.0,
       "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LiabilitiesFairValueDisclosure": {
     "auth_ref": [
      "r328"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Fair value of financial and nonfinancial obligations.",
        "label": "Liabilities Fair Value Disclosure",
        "verboseLabel": "Liabilities measured at fair value"
       }
      }
     },
     "localname": "LiabilitiesFairValueDisclosure",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_LongtermDebtTypeAxis": {
     "auth_ref": [
      "r47"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of long-term debt.",
        "label": "Longterm Debt Type [Axis]",
        "terseLabel": "Long-term Debt, Type"
       }
      }
     },
     "localname": "LongtermDebtTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_LongtermDebtTypeDomain": {
     "auth_ref": [
      "r47",
      "r199"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Type of long-term debt arrangement, such as notes, line of credit, commercial paper, asset-based financing, project financing, letter of credit financing. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the company, if longer.",
        "label": "Longterm Debt Type [Domain]",
        "terseLabel": "Long-term Debt, Type"
       }
      }
     },
     "localname": "LongtermDebtTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_MinorityInterestDisclosureTextBlock": {
     "auth_ref": [
      "r327"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for noncontrolling interest in consolidated subsidiaries, which could include the name of the subsidiary, the ownership percentage held by the parent, the ownership percentage held by the noncontrolling owners, the amount of the noncontrolling interest, the location of this amount on the balance sheet (when not reported separately), an explanation of the increase or decrease in the amount of the noncontrolling interest, the noncontrolling interest share of the net Income or Loss of the subsidiary, the location of this amount on the income statement (when not reported separately), the nature of the noncontrolling interest such as background information and terms, the amount of the noncontrolling interest represented by preferred stock, a description of the preferred stock, and the dividend requirements of the preferred stock.",
        "label": "Minority Interest Disclosure [Text Block]",
        "terseLabel": "Investment in Silver Creek"
       }
      }
     },
     "localname": "MinorityInterestDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreek"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_MoneyMarketFundsMember": {
     "auth_ref": [
      "r222"
     ],
     "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 [Member]"
       }
      }
     },
     "localname": "MoneyMarketFundsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfAssetsMeasuredAtFairValueOnRecurringBasisDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivities": {
     "auth_ref": [
      "r86"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10030.0,
       "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 used in financing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Net Cash Provided By Used In Financing Activities [Abstract]",
        "terseLabel": "Cash flows from financing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInFinancingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivities": {
     "auth_ref": [
      "r86"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10020.0,
       "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 provided by investing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Net Cash Provided By Used In Investing Activities [Abstract]",
        "terseLabel": "Cash flows from investing activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInInvestingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivities": {
     "auth_ref": [
      "r86",
      "r88",
      "r91"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10010.0,
       "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",
        "negatedLabel": "Cash in continuing operations for operating activities",
        "totalLabel": "Net cash used in operating activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Net Cash Provided By Used In Operating Activities [Abstract]",
        "terseLabel": "Cash flows from operating activities"
       }
      }
     },
     "localname": "NetCashProvidedByUsedInOperatingActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NetIncomeLoss": {
     "auth_ref": [
      "r17",
      "r56",
      "r59",
      "r66",
      "r91",
      "r100",
      "r108",
      "r110",
      "r111",
      "r112",
      "r113",
      "r115",
      "r116",
      "r121",
      "r149",
      "r158",
      "r161",
      "r164",
      "r166",
      "r173",
      "r341",
      "r374",
      "r385"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10030.0,
       "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",
        "totalLabel": "Net loss"
       }
      }
     },
     "localname": "NetIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy pertaining to new accounting pronouncements that may impact the entity's financial reporting. Includes, but is not limited to, quantification of the expected or actual impact.",
        "label": "New Accounting Pronouncements Policy Policy [Text Block]",
        "terseLabel": "Recently Adopted Accounting Pronouncements"
       }
      }
     },
     "localname": "NewAccountingPronouncementsPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_NoncontrollingInterestAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Noncontrolling Interest [Abstract]"
       }
      }
     },
     "localname": "NoncontrollingInterestAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_NonoperatingIncomeExpense": {
     "auth_ref": [
      "r73"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10110.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "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": "Total other income and expenses"
       }
      }
     },
     "localname": "NonoperatingIncomeExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_NonoperatingIncomeExpenseAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Nonoperating Income Expense [Abstract]",
        "terseLabel": "Other income and expenses:"
       }
      }
     },
     "localname": "NonoperatingIncomeExpenseAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_NumberOfOperatingSegments": {
     "auth_ref": [
      "r142"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "integerItemType"
    },
    "us-gaap_OneTimeTerminationBenefitsMember": {
     "auth_ref": [
      "r181"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "A lump sum payment to an involuntarily terminated employee in conjunction with exit or disposal activities.",
        "label": "One Time Termination Benefits [Member]",
        "terseLabel": "One-time Termination Benefits [Member]"
       }
      }
     },
     "localname": "OneTimeTerminationBenefitsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_OperatingExpenses": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10150.0,
       "parentTag": "us-gaap_OperatingIncomeLoss",
       "weight": -1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.",
        "label": "Operating Expenses",
        "totalLabel": "Total operating expenses"
       }
      }
     },
     "localname": "OperatingExpenses",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OperatingIncomeLoss": {
     "auth_ref": [
      "r149",
      "r158",
      "r161",
      "r164",
      "r166"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10100.0,
       "parentTag": "us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest",
       "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",
        "totalLabel": "Loss from continuing operations"
       }
      }
     },
     "localname": "OperatingIncomeLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLeasedAssetsLineItems": {
     "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": "Operating Leased Assets [Line Items]",
        "terseLabel": "Operating Leased Assets [Line Items]"
       }
      }
     },
     "localname": "OperatingLeasedAssetsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OperatingLeasesRentExpenseNet": {
     "auth_ref": [
      "r354"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.",
        "label": "Operating Leases Rent Expense Net",
        "terseLabel": "Total rent expense, net of rental income received from subleases"
       }
      }
     },
     "localname": "OperatingLeasesRentExpenseNet",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLossCarryforwards": {
     "auth_ref": [
      "r291"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.",
        "label": "Operating Loss Carryforwards",
        "terseLabel": "Net operating loss carryforwards"
       }
      }
     },
     "localname": "OperatingLossCarryforwards",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OperatingLossCarryforwardsLineItems": {
     "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": "Operating Loss Carryforwards [Line Items]",
        "terseLabel": "Operating Loss Carryforwards [Line Items]"
       }
      }
     },
     "localname": "OperatingLossCarryforwardsLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OperatingLossCarryforwardsTable": {
     "auth_ref": [
      "r292"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Schedule reflecting pertinent information, such as tax authority, amounts, and expiration dates, of net operating loss carryforwards, including an assessment of the likelihood of utilization.",
        "label": "Operating Loss Carryforwards [Table]",
        "terseLabel": "Operating Loss Carryforwards [Table]"
       }
      }
     },
     "localname": "OperatingLossCarryforwardsTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Organization Consolidation And Presentation Of Financial Statements [Abstract]"
       }
      }
     },
     "localname": "OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock": {
     "auth_ref": [
      "r104",
      "r117",
      "r141",
      "r327"
     ],
     "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": "Nature of the Business and Summary of Significant Accounting Policies"
       }
      }
     },
     "localname": "OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_OtherAssetsNoncurrent": {
     "auth_ref": [
      "r40"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10120.0,
       "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent": {
     "auth_ref": [
      "r313",
      "r314",
      "r319"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10050.0,
       "parentTag": "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent",
       "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 Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent",
        "terseLabel": "Unrealized gain on marketable securities"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent": {
     "auth_ref": [
      "r57",
      "r60",
      "r313",
      "r314",
      "r319"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10040.0,
       "parentTag": "us-gaap_ComprehensiveIncomeNetOfTax",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount after tax of other comprehensive income (loss) attributable to parent entity.",
        "label": "Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent",
        "totalLabel": "Other comprehensive loss"
       }
      }
     },
     "localname": "OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_OtherLiabilitiesCurrent": {
     "auth_ref": [
      "r22",
      "r23",
      "r45"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10100.0,
       "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 liability"
       }
      }
     },
     "localname": "OtherLiabilitiesCurrent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_OtherNonoperatingIncomeExpense": {
     "auth_ref": [
      "r74"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10140.0,
       "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 (expense), net"
       }
      }
     },
     "localname": "OtherNonoperatingIncomeExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaidInKindInterest": {
     "auth_ref": [
      "r90"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10150.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInOperatingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Interest paid other than in cash for example by issuing additional debt securities. As a noncash item, it is added to net income when calculating cash provided by or used in operations using the indirect method.",
        "label": "Paid In Kind Interest",
        "terseLabel": "Non-cash interest expense"
       }
      }
     },
     "localname": "PaidInKindInterest",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PayablesAndAccrualsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Payables And Accruals [Abstract]"
       }
      }
     },
     "localname": "PayablesAndAccrualsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_PaymentsForRestructuring": {
     "auth_ref": [
      "r84",
      "r183"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.",
        "label": "Payments For Restructuring",
        "negatedLabel": "Less: Payments",
        "terseLabel": "Payments for restructuring"
       }
      }
     },
     "localname": "PaymentsForRestructuring",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsOfDebtExtinguishmentCosts": {
     "auth_ref": [
      "r82"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10070.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.",
        "label": "Payments Of Debt Extinguishment Costs",
        "negatedLabel": "Payment of debt extinguishment costs"
       }
      }
     },
     "localname": "PaymentsOfDebtExtinguishmentCosts",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PaymentsOfDividends": {
     "auth_ref": [
      "r80"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10080.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.",
        "label": "Payments Of Dividends",
        "negatedLabel": "Payment of dividends"
       }
      }
     },
     "localname": "PaymentsOfDividends",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PlanNameAxis": {
     "auth_ref": [
      "r239",
      "r265"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by plan name for share-based payment arrangement.",
        "label": "Plan Name [Axis]",
        "terseLabel": "Plan Name"
       }
      }
     },
     "localname": "PlanNameAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PlanNameDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Plan name for share-based payment arrangement.",
        "label": "Plan Name [Domain]",
        "terseLabel": "Plan Name"
       }
      }
     },
     "localname": "PlanNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_PostemploymentBenefitsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Postemployment Benefits [Abstract]"
       }
      }
     },
     "localname": "PostemploymentBenefitsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_PreferredStockCallOrExerciseFeatures": {
     "auth_ref": [
      "r208",
      "r210"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Describe call and/or exercise rights, prices and dates of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer).",
        "label": "Preferred Stock Call Or Exercise Features",
        "terseLabel": "Preferred stock exercise features"
       }
      }
     },
     "localname": "PreferredStockCallOrExerciseFeatures",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PreferredStockParOrStatedValuePerShare": {
     "auth_ref": [
      "r28"
     ],
     "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",
        "terseLabel": "Preferred stock, par value"
       }
      }
     },
     "localname": "PreferredStockParOrStatedValuePerShare",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_PreferredStockRedemptionPricePerShare": {
     "auth_ref": [
      "r206",
      "r208",
      "r210"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer.",
        "label": "Preferred Stock Redemption Price Per Share",
        "terseLabel": "Preferred stock, redemption price per share"
       }
      }
     },
     "localname": "PreferredStockRedemptionPricePerShare",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_PreferredStockSharesAuthorized": {
     "auth_ref": [
      "r28"
     ],
     "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, shares authorized"
       }
      }
     },
     "localname": "PreferredStockSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesIssued": {
     "auth_ref": [
      "r28"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.",
        "label": "Preferred Stock Shares Issued",
        "terseLabel": "Preferred stock, shares issued"
       }
      }
     },
     "localname": "PreferredStockSharesIssued",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockSharesOutstanding": {
     "auth_ref": [
      "r28"
     ],
     "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, shares outstanding"
       }
      }
     },
     "localname": "PreferredStockSharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_PreferredStockValue": {
     "auth_ref": [
      "r28"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10040.0,
       "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",
        "terseLabel": "Preferred stock, $0.01 par value: 10,000 shares authorized at December 31, 2020 and 2019 no shares issued or outstanding at December 31, 2020 or 2019"
       }
      }
     },
     "localname": "PreferredStockValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PrepaidExpenseAndOtherAssetsCurrent": {
     "auth_ref": [
      "r20",
      "r35",
      "r36"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10140.0,
       "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromIssuanceOfLongTermDebt": {
     "auth_ref": [
      "r79"
     ],
     "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",
        "terseLabel": "Debt instrument, initial advance received"
       }
      }
     },
     "localname": "ProceedsFromIssuanceOfLongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities": {
     "auth_ref": [],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10090.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities  (held-to-maturity or available-for-sale) during the period.",
        "label": "Proceeds From Sale And Maturity Of Marketable Securities",
        "terseLabel": "Proceeds from sales and maturities of marketable securities",
        "verboseLabel": "Proceeds from maturities and sales of marketable securities"
       }
      }
     },
     "localname": "ProceedsFromSaleAndMaturityOfMarketableSecurities",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureInvestmentInSilverCreekAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleOfEquityMethodInvestments": {
     "auth_ref": [
      "r75"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10110.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.",
        "label": "Proceeds From Sale Of Equity Method Investments",
        "terseLabel": "Proceeds from sale of equity method investment"
       }
      }
     },
     "localname": "ProceedsFromSaleOfEquityMethodInvestments",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment": {
     "auth_ref": [
      "r76"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10120.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.",
        "label": "Proceeds From Sale Of Property Plant And Equipment",
        "terseLabel": "Proceeds from sale of property and equipment",
        "verboseLabel": "Proceeds on sale of property and equipment"
       }
      }
     },
     "localname": "ProceedsFromSaleOfPropertyPlantAndEquipment",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets": {
     "auth_ref": [
      "r77"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10130.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInInvestingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Aggregate cash proceeds received from a combination of transactions in which noncurrent assets are sold, which may include the sale of a business, an investment in an affiliate (including an equity method investee), property, plant and equipment and intangible assets. Excludes sales of trading, available-for-sale, and held-to-maturity securities.",
        "label": "Proceeds From Sales Of Business Affiliate And Productive Assets",
        "terseLabel": "Proceeds from sale of a discontinued operation"
       }
      }
     },
     "localname": "ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProceedsFromStockOptionsExercised": {
     "auth_ref": [
      "r78",
      "r266"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10040.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": 1.0
      }
     },
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash inflow from exercise of option under share-based payment arrangement.",
        "label": "Proceeds From Stock Options Exercised",
        "terseLabel": "Proceeds from exercise of options"
       }
      }
     },
     "localname": "ProceedsFromStockOptionsExercised",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ProfitLoss": {
     "auth_ref": [
      "r17",
      "r56",
      "r59",
      "r85",
      "r100",
      "r108",
      "r115",
      "r116",
      "r149",
      "r158",
      "r161",
      "r164",
      "r166",
      "r173",
      "r313",
      "r317",
      "r318",
      "r324",
      "r325",
      "r341",
      "r377"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10140.0,
       "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": "Profit Loss",
        "terseLabel": "Net loss",
        "totalLabel": "Net loss"
       }
      }
     },
     "localname": "ProfitLoss",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentByTypeAxis": {
     "auth_ref": [
      "r39",
      "r176"
     ],
     "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 By Type [Axis]",
        "terseLabel": "Long-Lived Tangible Asset"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentByTypeAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_PropertyPlantAndEquipmentTypeDomain": {
     "auth_ref": [
      "r26",
      "r175"
     ],
     "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": "Long-Lived Tangible Asset"
       }
      }
     },
     "localname": "PropertyPlantAndEquipmentTypeDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RepaymentsOfLongTermDebt": {
     "auth_ref": [
      "r81"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10050.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.",
        "label": "Repayments Of Long Term Debt",
        "negatedLabel": "Repayment of debt"
       }
      }
     },
     "localname": "RepaymentsOfLongTermDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RepaymentsOfOtherDebt": {
     "auth_ref": [
      "r81"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows": {
       "order": 10060.0,
       "parentTag": "us-gaap_NetCashProvidedByUsedInFinancingActivities",
       "weight": -1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of cash outflow for the payment of debt classified as other.",
        "label": "Repayments Of Other Debt",
        "terseLabel": "Repayment of other liability"
       }
      }
     },
     "localname": "RepaymentsOfOtherDebt",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ResearchAndDevelopmentExpense": {
     "auth_ref": [
      "r277",
      "r397"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss": {
       "order": 10160.0,
       "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 expenses"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpense",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ResearchAndDevelopmentExpenseMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Primary financial statement caption in which the reported facts about research and development expense have been included.",
        "label": "Research And Development Expense [Member]",
        "terseLabel": "Research and Development Expense [Member]"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpenseMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_ResearchAndDevelopmentExpensePolicy": {
     "auth_ref": [
      "r97",
      "r277"
     ],
     "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",
        "terseLabel": "Research and Development Expenses"
       }
      }
     },
     "localname": "ResearchAndDevelopmentExpensePolicy",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ResearchMember": {
     "auth_ref": [
      "r292"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Research tax credit carryforwards arising from certain qualifying expenditures incurred to develop new products and processes.",
        "label": "Research [Member]",
        "terseLabel": "Research and Development [Member]"
       }
      }
     },
     "localname": "ResearchMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RestructuringAndRelatedActivitiesAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Restructuring And Related Activities [Abstract]"
       }
      }
     },
     "localname": "RestructuringAndRelatedActivitiesAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock": {
     "auth_ref": [
      "r192"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The entire disclosure for restructuring and related activities. Description of restructuring activities such as exit and disposal activities, include facts and circumstances leading to the plan, the expected plan completion date, the major types of costs associated with the plan activities, total expected costs, the accrual balance at the end of the period, and the periods over which the remaining accrual will be settled.",
        "label": "Restructuring And Related Activities Disclosure [Text Block]",
        "terseLabel": "Restructuring Activities"
       }
      }
     },
     "localname": "RestructuringAndRelatedActivitiesDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivities"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_RestructuringAndRelatedActivitiesInitiationDate": {
     "auth_ref": [
      "r181",
      "r189"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Date the restructuring activities were initiated or are expected to be initiated, in CCYY-MM-DD format.",
        "label": "Restructuring And Related Activities Initiation Date",
        "terseLabel": "Restructuring activity, announcement date"
       }
      }
     },
     "localname": "RestructuringAndRelatedActivitiesInitiationDate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail"
     ],
     "xbrltype": "dateItemType"
    },
    "us-gaap_RestructuringCharges": {
     "auth_ref": [
      "r90",
      "r182",
      "r186",
      "r191"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.",
        "label": "Restructuring Charges",
        "terseLabel": "Restructuring expenses",
        "verboseLabel": "Expenses"
       }
      }
     },
     "localname": "RestructuringCharges",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RestructuringCostAndReserveAxis": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by type of restructuring cost.",
        "label": "Restructuring Cost And Reserve [Axis]",
        "terseLabel": "Restructuring Type"
       }
      }
     },
     "localname": "RestructuringCostAndReserveAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RestructuringCostAndReserveLineItems": {
     "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": "Restructuring Cost And Reserve [Line Items]",
        "terseLabel": "Restructuring Cost And Reserve [Line Items]"
       }
      }
     },
     "localname": "RestructuringCostAndReserveLineItems",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RestructuringPlanAxis": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by individual restructuring plan.",
        "label": "Restructuring Plan [Axis]",
        "terseLabel": "Restructuring Plan"
       }
      }
     },
     "localname": "RestructuringPlanAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_RestructuringPlanDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Identification of the individual restructuring plans.",
        "label": "Restructuring Plan [Domain]",
        "terseLabel": "Restructuring Plan"
       }
      }
     },
     "localname": "RestructuringPlanDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RestructuringReserveCurrent": {
     "auth_ref": [
      "r182",
      "r190"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail": {
       "order": 10050.0,
       "parentTag": "us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.",
        "label": "Restructuring Reserve Current",
        "periodEndLabel": "Accrued Restructuring Expenses",
        "periodStartLabel": "Accrued Restructuring Expenses",
        "terseLabel": "Accrued restructuring expenses",
        "verboseLabel": "Accrued restructuring expenses"
       }
      }
     },
     "localname": "RestructuringReserveCurrent",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherScheduleOfAccountsPayableAccruedExpensesAndOtherDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RestructuringReserveSettledWithoutCash2": {
     "auth_ref": [
      "r182",
      "r187"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of decrease in the reserve for full or partial settlement through consideration other than cash.",
        "label": "Restructuring Reserve Settled Without Cash2",
        "negatedLabel": "Less: Non-Cash Expenses"
       }
      }
     },
     "localname": "RestructuringReserveSettledWithoutCash2",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RetainedEarningsAccumulatedDeficit": {
     "auth_ref": [
      "r31",
      "r215",
      "r270",
      "r381",
      "r394",
      "r395"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10070.0,
       "parentTag": "us-gaap_StockholdersEquity",
       "weight": 1.0
      }
     },
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cumulative amount of the reporting entity's undistributed earnings or deficit.",
        "label": "Retained Earnings Accumulated Deficit",
        "negatedLabel": "Accumulated deficit",
        "terseLabel": "Accumulated deficit"
       }
      }
     },
     "localname": "RetainedEarningsAccumulatedDeficit",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RetainedEarningsMember": {
     "auth_ref": [
      "r105",
      "r106",
      "r107",
      "r109",
      "r114",
      "r116",
      "r174",
      "r267",
      "r268",
      "r269",
      "r296",
      "r297",
      "r391",
      "r393"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The cumulative amount of the reporting entity's undistributed earnings or deficit.",
        "label": "Retained Earnings [Member]",
        "terseLabel": "Accumulated Deficit [Member]"
       }
      }
     },
     "localname": "RetainedEarningsMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax": {
     "auth_ref": [
      "r143",
      "r144",
      "r157",
      "r162",
      "r163",
      "r167",
      "r168",
      "r169",
      "r217",
      "r218",
      "r367"
     ],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.",
        "label": "Revenue From Contract With Customer Including Assessed Tax",
        "terseLabel": "Cumulative worldwide net sales target"
       }
      }
     },
     "localname": "RevenueFromContractWithCustomerIncludingAssessedTax",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized": {
     "auth_ref": [],
     "crdr": "credit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The amount of consideration recognized during the period for the milestone or milestones.",
        "label": "Revenue Recognition Milestone Method Revenue Recognized",
        "terseLabel": "Milestone payment received"
       }
      }
     },
     "localname": "RevenueRecognitionMilestoneMethodRevenueRecognized",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of the (a) 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 (accounts payable); (b) other payables; and (c) accrued liabilities. 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). An alternative caption includes accrued expenses.",
        "label": "Schedule Of Accounts Payable And Accrued Liabilities Table [Text Block]",
        "terseLabel": "Schedule of Accounts Payable, Accrued Expenses and Other"
       }
      }
     },
     "localname": "ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureAccountsPayableAccruedExpensesAndOtherTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable": {
     "auth_ref": [
      "r125"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfSecuritiesExcludedFromComputationOfDilutedLossPerShareDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock": {
     "auth_ref": [
      "r125"
     ],
     "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 [Text Block]",
        "terseLabel": "Schedule of Securities Excluded from Computation of Diluted Loss Per Share"
       }
      }
     },
     "localname": "ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable": {
     "auth_ref": [
      "r311"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of information about collaborative arrangement and arrangement other than collaborative applicable to revenue-generating activity or operations.",
        "label": "Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table]",
        "terseLabel": "Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table]"
       }
      }
     },
     "localname": "ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock": {
     "auth_ref": [
      "r288"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of the components of net deferred tax asset or liability recognized in an entity's statement of financial position, including the following: the total of all deferred tax liabilities, the total of all deferred tax assets, the total valuation allowance recognized for deferred tax assets.",
        "label": "Schedule Of Deferred Tax Assets And Liabilities Table [Text Block]",
        "terseLabel": "Schedule of Temporary Differences That Give Rise to Significant Net Deferred Tax Assets"
       }
      }
     },
     "localname": "ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock": {
     "auth_ref": [
      "r0",
      "r6",
      "r7",
      "r8",
      "r9",
      "r10",
      "r11",
      "r13",
      "r15",
      "r16",
      "r17",
      "r178",
      "r179"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.",
        "label": "Schedule Of Disposal Groups Including Discontinued Operations Income Statement Balance Sheet And Additional Disclosures [Text Block]",
        "terseLabel": "Schedule of Discontinued Operations"
       }
      }
     },
     "localname": "ScheduleOfDisposalGroupsIncludingDiscontinuedOperationsIncomeStatementBalanceSheetAndAdditionalDisclosuresTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock": {
     "auth_ref": [
      "r281"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of the reconciliation using percentage or dollar amounts of the reported amount of income tax expense attributable to continuing operations for the year to the amount of income tax expense that would result from applying domestic federal statutory tax rates to pretax income from continuing operations.",
        "label": "Schedule Of Effective Income Tax Rate Reconciliation Table [Text Block]",
        "terseLabel": "Schedule of Reconciliation of the Company's Effective Tax Rate to the Statutory Federal Income Tax Rate"
       }
      }
     },
     "localname": "ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable": {
     "auth_ref": [
      "r238",
      "r261",
      "r272"
     ],
     "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": "Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]",
        "terseLabel": "Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table]"
       }
      }
     },
     "localname": "ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfRecognizedStockBasedCompensationExpenseDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfOperatingLeasedAssetsTable": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Schedule of long-lived, depreciable assets that are subject to a operating lease agreements and are used in the normal conduct of business to produce goods and services. Examples may 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": "Schedule Of Operating Leased Assets [Table]",
        "terseLabel": "Schedule Of Operating Leased Assets [Table]"
       }
      }
     },
     "localname": "ScheduleOfOperatingLeasedAssetsTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfRestructuringAndRelatedCostsTable": {
     "auth_ref": [
      "r184",
      "r185",
      "r188"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Table presenting the description of the restructuring costs, such as the expected cost; the costs incurred during the period; the cumulative costs incurred as of the balance sheet date; the income statement caption within which the restructuring charges recognized for the period are included; and the amount of and periodic changes to an entity's restructuring reserve that occurred during the period associated with the exit from or disposal of business activities or restructurings for each major type of cost by type of restructuring.",
        "label": "Schedule Of Restructuring And Related Costs [Table]",
        "terseLabel": "Schedule Of Restructuring And Related Costs [Table]"
       }
      }
     },
     "localname": "ScheduleOfRestructuringAndRelatedCostsTable",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock": {
     "auth_ref": [
      "r184",
      "r185",
      "r188"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of costs incurred for restructuring including, but not limited to, exit and disposal activities, remediation, implementation, integration, asset impairment, and charges against earnings from the write-down of assets.",
        "label": "Schedule Of Restructuring And Related Costs [Text Block]",
        "terseLabel": "Summary of Charges Related to Restructuring Activities"
       }
      }
     },
     "localname": "ScheduleOfRestructuringAndRelatedCostsTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable": {
     "auth_ref": [
      "r239",
      "r265"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock": {
     "auth_ref": [
      "r244",
      "r250",
      "r253"
     ],
     "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": "Schedule Of Share Based Compensation Stock Options Activity Table [Text Block]",
        "terseLabel": "Summary of Stock Option Activity"
       }
      }
     },
     "localname": "ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock": {
     "auth_ref": [
      "r255"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions.",
        "label": "Schedule Of Share Based Payment Award Stock Options Valuation Assumptions Table [Text Block]",
        "terseLabel": "Schedule of Assumptions Used to Calculate Fair Value of Options Granted to Employees"
       }
      }
     },
     "localname": "ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ScheduleOfStockByClassTable": {
     "auth_ref": [
      "r49",
      "r98",
      "r130",
      "r131",
      "r203",
      "r204",
      "r205",
      "r208",
      "r209",
      "r211",
      "r212",
      "r213",
      "r214",
      "r215"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_SegmentReportingPolicyPolicyTextBlock": {
     "auth_ref": [
      "r97",
      "r151",
      "r152",
      "r153",
      "r154",
      "r155",
      "r156",
      "r168"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for segment reporting.",
        "label": "Segment Reporting Policy Policy [Text Block]",
        "terseLabel": "Segment Information"
       }
      }
     },
     "localname": "SegmentReportingPolicyPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SellingGeneralAndAdministrativeExpensesPolicyTextBlock": {
     "auth_ref": [
      "r97",
      "r276"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Disclosure of accounting policy for inclusion of significant items in the selling, general and administrative (or similar) expense report caption.",
        "label": "Selling General And Administrative Expenses Policy [Text Block]",
        "terseLabel": "General and Administrative Expenses"
       }
      }
     },
     "localname": "SellingGeneralAndAdministrativeExpensesPolicyTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost": {
     "auth_ref": [],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of additional cost recognized for award under share-based payment arrangement from occurrence of event accelerating recognition of cost.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Accelerated Compensation Cost",
        "terseLabel": "Additional compensation expense"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1": {
     "auth_ref": [
      "r240"
     ],
     "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 Period1",
        "terseLabel": "Options vesting period"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate": {
     "auth_ref": [
      "r258"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate",
        "terseLabel": "Expected dividend yield"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate": {
     "auth_ref": [
      "r257"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate",
        "terseLabel": "Expected volatility"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate": {
     "auth_ref": [
      "r259"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The risk-free interest rate assumption that is used in valuing an option on its own shares.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate",
        "terseLabel": "Risk-free interest rate"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "percentItemType"
    },
    "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "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": "Additional common stock available for issuance (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant": {
     "auth_ref": [
      "r265"
     ],
     "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": "Shares of common stock available for grant (in shares)"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber": {
     "auth_ref": [
      "r247"
     ],
     "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": "Number of Options, Exercisable"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice": {
     "auth_ref": [
      "r247"
     ],
     "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": "Weighted-Average Exercise Price, Exercisable"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue": {
     "auth_ref": [
      "r252"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value",
        "terseLabel": "Aggregate intrinsic value of options exercised"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod": {
     "auth_ref": [
      "r249"
     ],
     "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": "Number of Options, Forfeited"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "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 Options, Granted"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue": {
     "auth_ref": [
      "r251"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value",
        "terseLabel": "Weighted-average grant date fair value per share of stock options"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue": {
     "auth_ref": [
      "r265"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value",
        "terseLabel": "Aggregate Intrinsic Value, Outstanding"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber": {
     "auth_ref": [
      "r246",
      "r265"
     ],
     "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": "Number of Options, Outstanding, Ending balance",
        "periodStartLabel": "Number of Options, Outstanding, Beginning balance"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "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"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice": {
     "auth_ref": [
      "r245"
     ],
     "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": "Weighted-Average Exercise Price, Outstanding, Ending balance",
        "periodStartLabel": "Weighted-Average Exercise Price, Outstanding, Beginning balance"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue": {
     "auth_ref": [
      "r253"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Aggregate Intrinsic Value",
        "terseLabel": "Aggregate Intrinsic Value, Vested and expected to vest"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber": {
     "auth_ref": [
      "r254"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number",
        "terseLabel": "Number of Options, Vested and expected to vest"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice": {
     "auth_ref": [
      "r254"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Exercise Price",
        "terseLabel": "Weighted-Average Exercise Price, Vested and expected to vest"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost": {
     "auth_ref": [
      "r263"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "An excess of the fair value of the modified award over the fair value of the award immediately before the modification.",
        "label": "Share Based Compensation Arrangement By Share Based Payment Award Plan Modification Incremental Compensation Cost",
        "terseLabel": "Incremental compensation expense"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain": {
     "auth_ref": [
      "r237",
      "r242"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Award under share-based payment arrangement.",
        "label": "Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain]",
        "terseLabel": "Award Type"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "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": "Weighted-Average Exercise Price, Exercised"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "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": "Weighted-Average Exercise Price, Forfeited"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "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": "Weighted-Average Exercise Price, Granted"
       }
      }
     },
     "localname": "ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "perShareItemType"
    },
    "us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy": {
     "auth_ref": [
      "r97",
      "r239",
      "r243"
     ],
     "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 Compensation Option And Incentive Plans Policy",
        "terseLabel": "Stock-Based Compensation Expense"
       }
      }
     },
     "localname": "ShareBasedCompensationOptionAndIncentivePlansPolicy",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod": {
     "auth_ref": [
      "r241"
     ],
     "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": "Sharebased Compensation Arrangement By Sharebased Payment Award Expiration Period",
        "terseLabel": "Contractual term"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1": {
     "auth_ref": [
      "r256",
      "r271"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.",
        "label": "Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1",
        "terseLabel": "Expected term"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedToCalculateFairValueOfOptionsGrantedToEmployeesDetail"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1": {
     "auth_ref": [
      "r265"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.",
        "label": "Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1",
        "terseLabel": "Aggregate Intrinsic Value, Exercisable"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1": {
     "auth_ref": [
      "r265"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1",
        "terseLabel": "Weighted-Average Remaining Contractual Term, Exercisable"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2": {
     "auth_ref": [
      "r254"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.",
        "label": "Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2",
        "terseLabel": "Weighted-Average Remaining Contractual Term"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "xbrltype": "durationItemType"
    },
    "us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1": {
     "auth_ref": [
      "r254"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.",
        "label": "Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term1",
        "terseLabel": "Weighted-Average Remaining Contractual Term, Vested and expected to vest"
       }
      }
     },
     "localname": "SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail"
     ],
     "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": "Balance (in shares)",
        "periodStartLabel": "Balance (in shares)"
       }
      }
     },
     "localname": "SharesOutstanding",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StateAndLocalJurisdictionMember": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Designated tax department of a state or local government entitled to levy and collect income taxes from the entity.",
        "label": "State And Local Jurisdiction [Member]",
        "terseLabel": "State [Member]"
       }
      }
     },
     "localname": "StateAndLocalJurisdictionMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_StatementClassOfStockAxis": {
     "auth_ref": [
      "r27",
      "r28",
      "r29",
      "r98",
      "r100",
      "r118",
      "r119",
      "r120",
      "r122",
      "r124",
      "r130",
      "r131",
      "r132",
      "r173",
      "r207",
      "r341"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by the different classes of stock of the entity.",
        "label": "Statement Class Of Stock [Axis]",
        "terseLabel": "Class of Stock"
       }
      }
     },
     "localname": "StatementClassOfStockAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementEquityComponentsAxis": {
     "auth_ref": [
      "r50",
      "r105",
      "r106",
      "r107",
      "r109",
      "r114",
      "r116",
      "r129",
      "r174",
      "r207",
      "r215",
      "r267",
      "r268",
      "r269",
      "r296",
      "r297",
      "r343",
      "r344",
      "r345",
      "r346",
      "r347",
      "r348",
      "r391",
      "r392",
      "r393"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by component of equity.",
        "label": "Statement Equity Components [Axis]",
        "terseLabel": "Accumulated Other Comprehensive Loss [Member]"
       }
      }
     },
     "localname": "StatementEquityComponentsAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfCashFlowsAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement Of Cash Flows [Abstract]"
       }
      }
     },
     "localname": "StatementOfCashFlowsAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfFinancialPositionAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement Of Financial Position [Abstract]"
       }
      }
     },
     "localname": "StatementOfFinancialPositionAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement Of Income And Comprehensive Income [Abstract]"
       }
      }
     },
     "localname": "StatementOfIncomeAndComprehensiveIncomeAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementOfStockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Statement Of Stockholders Equity [Abstract]"
       }
      }
     },
     "localname": "StatementOfStockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "xbrltype": "stringItemType"
    },
    "us-gaap_StatementTable": {
     "auth_ref": [
      "r105",
      "r106",
      "r107",
      "r129",
      "r367"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockCompensationPlanMember": {
     "auth_ref": [
      "r125"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Share-based payment arrangement in which award of equity shares are granted. Arrangement includes, but is not limited to, grantor incurring liability for product and service based on price of its shares.",
        "label": "Stock Compensation Plan [Member]",
        "terseLabel": "Outstanding Options to Purchase Common Stock [Member]"
       }
      }
     },
     "localname": "StockCompensationPlanMember",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNetLossPerCommonShareScheduleOfSecuritiesExcludedFromComputationOfDilutedLossPerShareDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised": {
     "auth_ref": [
      "r28",
      "r29",
      "r207",
      "r215",
      "r248"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Number of share options (or share units) exercised during the current period.",
        "label": "Stock Issued During Period Shares Stock Options Exercised",
        "negatedLabel": "Number of Options, Exercised",
        "terseLabel": "Exercise of stock options (shares)"
       }
      }
     },
     "localname": "StockIssuedDuringPeriodSharesStockOptionsExercised",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "sharesItemType"
    },
    "us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised": {
     "auth_ref": [
      "r50",
      "r207",
      "r215"
     ],
     "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/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquity": {
     "auth_ref": [
      "r29",
      "r32",
      "r33",
      "r100",
      "r171",
      "r173",
      "r341"
     ],
     "calculation": {
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets": {
       "order": 10030.0,
       "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",
        "periodEndLabel": "Balance",
        "periodStartLabel": "Balance",
        "totalLabel": "Total stockholders\u2019 equity"
       }
      }
     },
     "localname": "StockholdersEquity",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquity"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_StockholdersEquityAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Stockholders Equity [Abstract]",
        "terseLabel": "Stockholders\u2019 equity:"
       }
      }
     },
     "localname": "StockholdersEquityAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedBalanceSheets"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_StockholdersEquityNoteDisclosureTextBlock": {
     "auth_ref": [
      "r99",
      "r215",
      "r216"
     ],
     "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": "Common Stock"
       }
      }
     },
     "localname": "StockholdersEquityNoteDisclosureTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStock"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SummaryOfValuationAllowanceTextBlock": {
     "auth_ref": [
      "r287"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Tabular disclosure of valuation allowances to reduce deferred tax assets to net realizable value, including identification of the deferred tax asset more likely than not will not be fully realized and the corresponding amount of the valuation allowance.",
        "label": "Summary Of Valuation Allowance [Text Block]",
        "terseLabel": "Schedule of Changes in the Valuation Allowance"
       }
      }
     },
     "localname": "SummaryOfValuationAllowanceTextBlock",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesTables"
     ],
     "xbrltype": "textBlockItemType"
    },
    "us-gaap_SupplementalCashFlowInformationAbstract": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "label": "Supplemental Cash Flow Information [Abstract]",
        "terseLabel": "Supplemental disclosure of cash flows"
       }
      }
     },
     "localname": "SupplementalCashFlowInformationAbstract",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TaxCreditCarryforwardAmount": {
     "auth_ref": [
      "r291"
     ],
     "crdr": "debit",
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.",
        "label": "Tax Credit Carryforward Amount",
        "terseLabel": "Amount of tax credit carryforward"
       }
      }
     },
     "localname": "TaxCreditCarryforwardAmount",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "monetaryItemType"
    },
    "us-gaap_TaxCreditCarryforwardAxis": {
     "auth_ref": [
      "r292"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by specific tax credit related to an unused tax credit.",
        "label": "Tax Credit Carryforward [Axis]",
        "terseLabel": "Tax Credit Carryforward"
       }
      }
     },
     "localname": "TaxCreditCarryforwardAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TaxCreditCarryforwardNameDomain": {
     "auth_ref": [
      "r292"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "The name of the tax credit carryforward.",
        "label": "Tax Credit Carryforward Name [Domain]",
        "terseLabel": "Tax Credit Carryforward, Name"
       }
      }
     },
     "localname": "TaxCreditCarryforwardNameDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_TypeOfArrangementAxis": {
     "auth_ref": [
      "r311"
     ],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Information by collaborative arrangement and arrangement other than collaborative applicable to revenue-generating activity or operations.",
        "label": "Type Of Arrangement [Axis]",
        "terseLabel": "Collaborative Arrangement and Arrangement Other than Collaborative"
       }
      }
     },
     "localname": "TypeOfArrangementAxis",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureBorrowingsLoanAgreementAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureCommonStockAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureDiscontinuedOperationsSaleOfCommercialBusinessAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureLicenseAndCollaborationAgreementsAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail"
     ],
     "xbrltype": "stringItemType"
    },
    "us-gaap_TypeOfRestructuringDomain": {
     "auth_ref": [],
     "lang": {
      "en-us": {
       "role": {
        "documentation": "Identification of the types of restructuring costs.",
        "label": "Type Of Restructuring [Domain]",
        "terseLabel": "Type of Restructuring"
       }
      }
     },
     "localname": "TypeOfRestructuringDomain",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesAdditionalInformationDetail",
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureRestructuringActivitiesSummaryOfChargesRelatedToRestructuringActivitiesDetail"
     ],
     "xbrltype": "domainItemType"
    },
    "us-gaap_UseOfEstimates": {
     "auth_ref": [
      "r133",
      "r134",
      "r136",
      "r137",
      "r138",
      "r139",
      "r140"
     ],
     "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",
        "terseLabel": "Use of Estimates"
       }
      }
     },
     "localname": "UseOfEstimates",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/DisclosureNatureOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies"
     ],
     "xbrltype": "textBlockItemType"
    },
    "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 Share Outstanding Basic And Diluted",
        "terseLabel": "Weighted-average common shares used in per share calculations\u2014basic and diluted"
       }
      }
     },
     "localname": "WeightedAverageNumberOfShareOutstandingBasicAndDiluted",
     "nsuri": "http://fasb.org/us-gaap/2020-01-31",
     "presentation": [
      "http://www.merrimackpharma.com/20201231/taxonomy/role/StatementConsolidatedStatementsOfOperationsAndComprehensiveLoss"
     ],
     "xbrltype": "sharesItemType"
    }
   },
   "unitCount": 7
  }
 },
 "std_ref": {
  "r0": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721533-107759"
  },
  "r1": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=d3e957-107759"
  },
  "r10": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721665-107760"
  },
  "r100": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(g)(1)(ii))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r101": {
   "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=120395691&loc=d3e23780-122690"
  },
  "r102": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(m)(1)(iii))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r103": {
   "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=120395691&loc=d3e23780-122690"
  },
  "r104": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "235",
   "URI": "http://asc.fasb.org/topic&trid=2122369"
  },
  "r105": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "23",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=115929471&loc=d3e21914-107793"
  },
  "r106": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "24",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=115929471&loc=d3e21930-107793"
  },
  "r107": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=115929471&loc=d3e21711-107793"
  },
  "r108": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(2)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r109": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(3)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794"
  },
  "r11": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721671-107760"
  },
  "r110": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794"
  },
  "r111": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794"
  },
  "r112": {
   "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"
  },
  "r113": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794"
  },
  "r114": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22644-107794"
  },
  "r115": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794"
  },
  "r116": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "250",
   "URI": "http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794"
  },
  "r117": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "250",
   "URI": "http://asc.fasb.org/topic&trid=2122394"
  },
  "r118": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1252-109256"
  },
  "r119": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1278-109256"
  },
  "r12": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760"
  },
  "r120": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "55",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e2626-109256"
  },
  "r121": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "60B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256"
  },
  "r122": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "60B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256"
  },
  "r123": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=121326447&loc=d3e1337-109256"
  },
  "r124": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257"
  },
  "r125": {
   "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"
  },
  "r126": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=6371337&loc=d3e3630-109257"
  },
  "r127": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "260",
   "URI": "http://asc.fasb.org/extlink&oid=109243012&loc=SL65017193-207537"
  },
  "r128": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "260",
   "URI": "http://asc.fasb.org/topic&trid=2144383"
  },
  "r129": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6828210&loc=d3e70191-108054"
  },
  "r13": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5B",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760"
  },
  "r130": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6828210&loc=d3e70229-108054"
  },
  "r131": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055"
  },
  "r132": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "272",
   "URI": "http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055"
  },
  "r133": {
   "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"
  },
  "r134": {
   "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"
  },
  "r135": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "275",
   "URI": "http://asc.fasb.org/extlink&oid=99393423&loc=d3e5967-108592"
  },
  "r136": {
   "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"
  },
  "r137": {
   "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"
  },
  "r138": {
   "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"
  },
  "r139": {
   "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"
  },
  "r14": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(2)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721675-107760"
  },
  "r140": {
   "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"
  },
  "r141": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "275",
   "URI": "http://asc.fasb.org/topic&trid=2134479"
  },
  "r142": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "18",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599"
  },
  "r143": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r144": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r145": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r146": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r147": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r148": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r149": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "22",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599"
  },
  "r15": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5C",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721675-107760"
  },
  "r150": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8813-108599"
  },
  "r151": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8864-108599"
  },
  "r152": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8864-108599"
  },
  "r153": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8864-108599"
  },
  "r154": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8864-108599"
  },
  "r155": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8864-108599"
  },
  "r156": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8864-108599"
  },
  "r157": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599"
  },
  "r158": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599"
  },
  "r159": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599"
  },
  "r16": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5D",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721677-107760"
  },
  "r160": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "30",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599"
  },
  "r161": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "31",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599"
  },
  "r162": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r163": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r164": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r165": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r166": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "32",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599"
  },
  "r167": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "40",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599"
  },
  "r168": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "41",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599"
  },
  "r169": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "42",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "280",
   "URI": "http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599"
  },
  "r17": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760"
  },
  "r170": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "310",
   "URI": "http://asc.fasb.org/extlink&oid=121593590&loc=d3e4647-111522"
  },
  "r171": {
   "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"
  },
  "r172": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "323",
   "URI": "http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570"
  },
  "r173": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "323",
   "URI": "http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571"
  },
  "r174": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "326",
   "URI": "http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437"
  },
  "r175": {
   "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"
  },
  "r176": {
   "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"
  },
  "r177": {
   "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"
  },
  "r178": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230"
  },
  "r179": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "360",
   "URI": "http://asc.fasb.org/extlink&oid=109226691&loc=SL51724579-110230"
  },
  "r18": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/subtopic&trid=2122178"
  },
  "r180": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "360",
   "URI": "http://asc.fasb.org/topic&trid=2155823"
  },
  "r181": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869"
  },
  "r182": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869"
  },
  "r183": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)(2)",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869"
  },
  "r184": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869"
  },
  "r185": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB TOPIC 5.P.3)",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=115931487&loc=d3e140864-122747"
  },
  "r186": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 5.P.3)",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=115931487&loc=d3e140864-122747"
  },
  "r187": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB TOPIC 5.P.4(b)(2))",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747"
  },
  "r188": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB TOPIC 5.P.4)",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747"
  },
  "r189": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 5.P.4(a))",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747"
  },
  "r19": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=121566466&loc=d3e6676-107765"
  },
  "r190": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 5.P.4(b)(2))",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747"
  },
  "r191": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 5.P.4(b))",
   "Topic": "420",
   "URI": "http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747"
  },
  "r192": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "420",
   "URI": "http://asc.fasb.org/topic&trid=2175745"
  },
  "r193": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "440",
   "URI": "http://asc.fasb.org/extlink&oid=121559207&loc=d3e25336-109308"
  },
  "r194": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "440",
   "URI": "http://asc.fasb.org/extlink&oid=121559207&loc=d3e25336-109308"
  },
  "r195": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "440",
   "URI": "http://asc.fasb.org/topic&trid=2144648"
  },
  "r196": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349"
  },
  "r197": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "450",
   "URI": "http://asc.fasb.org/extlink&oid=121557415&loc=d3e14615-108349"
  },
  "r198": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "450",
   "URI": "http://asc.fasb.org/topic&trid=2127136"
  },
  "r199": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=6802200&loc=SL6230698-112601"
  },
  "r2": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721523-107759"
  },
  "r20": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=121566466&loc=d3e6676-107765"
  },
  "r200": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "40",
   "SubTopic": "50",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=117329964&loc=d3e12317-112629"
  },
  "r201": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "40",
   "SubTopic": "50",
   "Topic": "470",
   "URI": "http://asc.fasb.org/extlink&oid=117329964&loc=d3e12355-112629"
  },
  "r202": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "470",
   "URI": "http://asc.fasb.org/topic&trid=2208564"
  },
  "r203": {
   "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"
  },
  "r204": {
   "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"
  },
  "r205": {
   "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"
  },
  "r206": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21564-112644"
  },
  "r207": {
   "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"
  },
  "r208": {
   "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"
  },
  "r209": {
   "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"
  },
  "r21": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=121566466&loc=d3e6801-107765"
  },
  "r210": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=109259400&loc=d3e21488-112644"
  },
  "r211": {
   "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"
  },
  "r212": {
   "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"
  },
  "r213": {
   "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"
  },
  "r214": {
   "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"
  },
  "r215": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.3-04)",
   "Topic": "505",
   "URI": "http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770"
  },
  "r216": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "505",
   "URI": "http://asc.fasb.org/topic&trid=2208762"
  },
  "r217": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045"
  },
  "r218": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "606",
   "URI": "http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045"
  },
  "r219": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "710",
   "URI": "http://asc.fasb.org/topic&trid=2127225"
  },
  "r22": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=121566466&loc=d3e6904-107765"
  },
  "r220": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "712",
   "URI": "http://asc.fasb.org/topic&trid=2197446"
  },
  "r221": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(i)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r222": {
   "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"
  },
  "r223": {
   "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"
  },
  "r224": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r225": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)(A)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r226": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)(B)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r227": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(02)(C)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r228": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(d)(iv)(03)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920"
  },
  "r229": {
   "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"
  },
  "r23": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=121566466&loc=d3e6911-107765"
  },
  "r230": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "80",
   "Subparagraph": "(a)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=65877416&loc=SL14450702-114947"
  },
  "r231": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "80",
   "Subparagraph": "(d)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947"
  },
  "r232": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "80",
   "Subparagraph": "(f)(3)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947"
  },
  "r233": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "80",
   "Subparagraph": "(a)",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=65877416&loc=SL14450673-114947"
  },
  "r234": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "80",
   "Topic": "715",
   "URI": "http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948"
  },
  "r235": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "715",
   "URI": "http://asc.fasb.org/topic&trid=2235017"
  },
  "r236": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "35",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121326096&loc=d3e4534-113899"
  },
  "r237": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r238": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r239": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901"
  },
  "r24": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=121566466&loc=d3e6935-107765"
  },
  "r240": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r241": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r242": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a),(g)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r243": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b),(f)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r244": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r245": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r246": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(i)-(ii)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r247": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(iii)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r248": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(iv)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r249": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)(1)(iv)(3)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r25": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(1))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r250": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r251": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r252": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r253": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r254": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r255": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r256": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r257": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)(ii)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r258": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)(iii)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r259": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)(iv)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r26": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(13))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r260": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(g)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r261": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r262": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)(1)(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r263": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(h)(2)(iii)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r264": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(i)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r265": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901"
  },
  "r266": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120381028&loc=SL79508275-113901"
  },
  "r267": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r268": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(f)(1)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r269": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(f)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r27": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(27))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r270": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(g)(2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333"
  },
  "r271": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 14.D.2)",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809"
  },
  "r272": {
   "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"
  },
  "r273": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120383193&loc=d3e11149-113907"
  },
  "r274": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "13",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "20",
   "Topic": "718",
   "URI": "http://asc.fasb.org/extlink&oid=120383193&loc=d3e11178-113907"
  },
  "r275": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "718",
   "URI": "http://asc.fasb.org/topic&trid=2228938"
  },
  "r276": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "35",
   "Subparagraph": "(a)",
   "Topic": "720",
   "URI": "http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848"
  },
  "r277": {
   "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"
  },
  "r278": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=120406818&loc=d3e32247-109318"
  },
  "r279": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=120406818&loc=d3e32280-109318"
  },
  "r28": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(28))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r280": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32672-109319"
  },
  "r281": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319"
  },
  "r282": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32705-109319"
  },
  "r283": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319"
  },
  "r284": {
   "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"
  },
  "r285": {
   "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"
  },
  "r286": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319"
  },
  "r287": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319"
  },
  "r288": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319"
  },
  "r289": {
   "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"
  },
  "r29": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(29))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r290": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "21",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32857-109319"
  },
  "r291": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319"
  },
  "r292": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319"
  },
  "r293": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319"
  },
  "r294": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319"
  },
  "r295": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "9",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319"
  },
  "r296": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)(2)",
   "Topic": "740"
  },
  "r297": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "10",
   "Subparagraph": "(d)(3)",
   "Topic": "740"
  },
  "r298": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB TOPIC 6.I.5.Q1)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817"
  },
  "r299": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB TOPIC 6.I.7)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817"
  },
  "r3": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=SL51721525-107759"
  },
  "r30": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30)(a)(1))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r300": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 6.I.Fact.4)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817"
  },
  "r301": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 11.C)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=116825942&loc=d3e330215-122817"
  },
  "r302": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324"
  },
  "r303": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324"
  },
  "r304": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324"
  },
  "r305": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "270",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=109227538&loc=d3e44648-109337"
  },
  "r306": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "270",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338"
  },
  "r307": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "740",
   "URI": "http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331"
  },
  "r308": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "740",
   "URI": "http://asc.fasb.org/topic&trid=2144680"
  },
  "r309": {
   "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"
  },
  "r31": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30)(a)(3))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r310": {
   "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"
  },
  "r311": {
   "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"
  },
  "r312": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "808",
   "URI": "http://asc.fasb.org/topic&trid=5833765"
  },
  "r313": {
   "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"
  },
  "r314": {
   "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"
  },
  "r315": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988"
  },
  "r316": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988"
  },
  "r317": {
   "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"
  },
  "r318": {
   "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"
  },
  "r319": {
   "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"
  },
  "r32": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(30))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r320": {
   "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"
  },
  "r321": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684"
  },
  "r322": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bb)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=121559654&loc=d3e5710-111685"
  },
  "r323": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=121559654&loc=d3e5710-111685"
  },
  "r324": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4J",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=120409616&loc=SL4591551-111686"
  },
  "r325": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4K",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=120409616&loc=SL4591552-111686"
  },
  "r326": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4M",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "10",
   "Topic": "810",
   "URI": "http://asc.fasb.org/extlink&oid=120409616&loc=SL4591554-111686"
  },
  "r327": {
   "Name": "Accounting Standards Codification",
   "Publisher": "FASB",
   "Topic": "810",
   "URI": "http://asc.fasb.org/topic&trid=2197479"
  },
  "r328": {
   "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"
  },
  "r329": {
   "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"
  },
  "r33": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(31))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r330": {
   "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"
  },
  "r331": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bbb)(1)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r332": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(bbb)(2)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r333": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258"
  },
  "r334": {
   "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"
  },
  "r335": {
   "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"
  },
  "r336": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "820",
   "URI": "http://asc.fasb.org/extlink&oid=117815213&loc=SL6742756-110258"
  },
  "r337": {
   "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"
  },
  "r338": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=121572278&loc=d3e13279-108611"
  },
  "r339": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "11",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=121572278&loc=d3e13467-108611"
  },
  "r34": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(32))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r340": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=121572278&loc=d3e13476-108611"
  },
  "r341": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "825",
   "URI": "http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612"
  },
  "r342": {
   "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"
  },
  "r343": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32136-110900"
  },
  "r344": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(a)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r345": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(b)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r346": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(c)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r347": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "20",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Subparagraph": "(d)",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900"
  },
  "r348": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "30",
   "Topic": "830",
   "URI": "http://asc.fasb.org/extlink&oid=6450520&loc=d3e32583-110901"
  },
  "r349": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(a)",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391"
  },
  "r35": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(7))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r350": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399"
  },
  "r351": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399"
  },
  "r352": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399"
  },
  "r353": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "30",
   "Topic": "835",
   "URI": "http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400"
  },
  "r354": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "840",
   "URI": "http://asc.fasb.org/extlink&oid=121573735&loc=d3e41499-112717"
  },
  "r355": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "850",
   "URI": "http://asc.fasb.org/extlink&oid=6457730&loc=d3e39599-107864"
  },
  "r356": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "855",
   "URI": "http://asc.fasb.org/extlink&oid=6842918&loc=SL6314020-165662"
  },
  "r357": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r358": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r359": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(bb)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r36": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02(8))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r360": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r361": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r362": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(c)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719"
  },
  "r363": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(1)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r364": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(2)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r365": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)(3)",
   "Topic": "860",
   "URI": "http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719"
  },
  "r366": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "6",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "910",
   "URI": "http://asc.fasb.org/extlink&oid=119991564&loc=SL119991595-234733"
  },
  "r367": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SAB Topic 11.L)",
   "Topic": "924",
   "URI": "http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856"
  },
  "r368": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "25",
   "SubTopic": "20",
   "Topic": "940",
   "URI": "http://asc.fasb.org/extlink&oid=68072869&loc=d3e41242-110953"
  },
  "r369": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(1)(a))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r37": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.1)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r370": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(11))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r371": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03(23))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r372": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.9-03.17)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878"
  },
  "r373": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(15))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r374": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(22))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r375": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04(26))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r376": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.9-04.9)",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260"
  },
  "r377": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "235",
   "Subparagraph": "(SX 210.9-05(b)(2))",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884"
  },
  "r378": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "470",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823"
  },
  "r379": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "825",
   "Topic": "942",
   "URI": "http://asc.fasb.org/extlink&oid=108315417&loc=d3e61044-112788"
  },
  "r38": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.12)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r380": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(12))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r381": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(23)(a)(4))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r382": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03(a)(25))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r383": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "210",
   "Subparagraph": "(SX 210.7-03.(a),19)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910"
  },
  "r384": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(12))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r385": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(18))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r386": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(22))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r387": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(8))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r388": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "220",
   "Subparagraph": "(SX 210.7-04(9))",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263"
  },
  "r389": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "7A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "40",
   "Subparagraph": "(d)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121643868&loc=SL117782755-158439"
  },
  "r39": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.14)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r390": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "29F",
   "Publisher": "FASB",
   "Section": "55",
   "SubTopic": "40",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121639165&loc=SL117819544-158441"
  },
  "r391": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(e)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r392": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(f)(1)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r393": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(f)(2)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r394": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(g)(2)(i)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r395": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "65",
   "SubTopic": "40",
   "Subparagraph": "(h)(2)",
   "Topic": "944",
   "URI": "http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641"
  },
  "r396": {
   "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"
  },
  "r397": {
   "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"
  },
  "r398": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b"
  },
  "r399": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b-23"
  },
  "r4": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222160&loc=d3e1012-107759"
  },
  "r40": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.17)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r400": {
   "Name": "Exchange Act",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "d1-1"
  },
  "r401": {
   "Name": "Form 10-K",
   "Number": "249",
   "Publisher": "SEC",
   "Section": "310"
  },
  "r402": {
   "Name": "Form 20-F",
   "Number": "249",
   "Publisher": "SEC",
   "Section": "220",
   "Subsection": "f"
  },
  "r403": {
   "Name": "Form 40-F",
   "Number": "249",
   "Publisher": "SEC",
   "Section": "240",
   "Subsection": "f"
  },
  "r404": {
   "Name": "Forms 10-K, 10-Q, 20-F",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "13",
   "Subsection": "a-1"
  },
  "r405": {
   "Name": "Regulation 12B",
   "Number": "240",
   "Publisher": "SEC",
   "Section": "12",
   "Subsection": "b-2"
  },
  "r406": {
   "Name": "Regulation S-T",
   "Number": "232",
   "Publisher": "SEC",
   "Section": "405"
  },
  "r41": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19(a))",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r42": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19(a),20,24)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r43": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19,20)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r44": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.19-26)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r45": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.20)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r46": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.21)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r47": {
   "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=120391452&loc=d3e13212-122682"
  },
  "r48": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.25)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r49": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.28,29)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r5": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Subparagraph": "(b)",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=d3e1361-107760"
  },
  "r50": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.29-31)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r51": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-02.9)",
   "Topic": "210",
   "URI": "http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682"
  },
  "r52": {
   "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"
  },
  "r53": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "10A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580"
  },
  "r54": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669686-108580"
  },
  "r55": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL34724394-108580"
  },
  "r56": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580"
  },
  "r57": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580"
  },
  "r58": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1A",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580"
  },
  "r59": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580"
  },
  "r6": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=d3e1361-107760"
  },
  "r60": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1B",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580"
  },
  "r61": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "5",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=121641772&loc=d3e557-108580"
  },
  "r62": {
   "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"
  },
  "r63": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(210.5-03(11))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r64": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(10))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r65": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(14))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r66": {
   "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=120395209&loc=SL114868664-224227"
  },
  "r67": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(24))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r68": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(4))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r69": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(b)(7)(c))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r7": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=d3e1474-107760"
  },
  "r70": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03(b)(9)(a))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r71": {
   "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=120395209&loc=SL114868664-224227"
  },
  "r72": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.5-03.7(b))",
   "Topic": "220",
   "URI": "http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227"
  },
  "r73": {
   "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=120395209&loc=SL114868664-224227"
  },
  "r74": {
   "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=120395209&loc=SL114868664-224227"
  },
  "r75": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585"
  },
  "r76": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(c)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585"
  },
  "r77": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "12",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585"
  },
  "r78": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585"
  },
  "r79": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "14",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585"
  },
  "r8": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721659-107760"
  },
  "r80": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585"
  },
  "r81": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585"
  },
  "r82": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "15",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(g)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585"
  },
  "r83": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(d)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3367-108585"
  },
  "r84": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "17",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(f)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3367-108585"
  },
  "r85": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3000-108585"
  },
  "r86": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "24",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3521-108585"
  },
  "r87": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(e)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585"
  },
  "r88": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "25",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585"
  },
  "r89": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(a)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585"
  },
  "r9": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4A",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "20",
   "Topic": "205",
   "URI": "http://asc.fasb.org/extlink&oid=109222650&loc=SL51721663-107760"
  },
  "r90": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Subparagraph": "(b)",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585"
  },
  "r91": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "28",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585"
  },
  "r92": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "4",
   "Publisher": "FASB",
   "Section": "45",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121586364&loc=d3e3044-108585"
  },
  "r93": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=d3e4273-108586"
  },
  "r94": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "2",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=d3e4297-108586"
  },
  "r95": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "3",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=d3e4304-108586"
  },
  "r96": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "8",
   "Publisher": "FASB",
   "Section": "50",
   "SubTopic": "10",
   "Topic": "230",
   "URI": "http://asc.fasb.org/extlink&oid=121583591&loc=SL98516268-108586"
  },
  "r97": {
   "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"
  },
  "r98": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(d))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  },
  "r99": {
   "Name": "Accounting Standards Codification",
   "Paragraph": "1",
   "Publisher": "FASB",
   "Section": "S99",
   "SubTopic": "10",
   "Subparagraph": "(SX 210.4-08(e)(1))",
   "Topic": "235",
   "URI": "http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690"
  }
 },
 "version": "2.1"
}
