3.19.1 html 494 491 1 false 143 0 false 21 false false R1.htm 0001000 - Document - Document and Entity Information Sheet http://www.assertiotx.com/role/DocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 1001000 - Statement - CONSOLIDATED BALANCE SHEETS Sheet http://www.assertiotx.com/role/ConsolidatedBalanceSheets CONSOLIDATED BALANCE SHEETS Statements 2 false false R3.htm 1001501 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical) Sheet http://www.assertiotx.com/role/ConsolidatedBalanceSheetsParenthetical CONSOLIDATED BALANCE SHEETS (Parenthetical) Statements 3 false false R4.htm 1002000 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS Sheet http://www.assertiotx.com/role/ConsolidatedStatementsOfOperations CONSOLIDATED STATEMENTS OF OPERATIONS Statements 4 false false R5.htm 1003000 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE iNCOME / LOSS Sheet http://www.assertiotx.com/role/ConsolidatedStatementsOfComprehensiveIncomeLoss CONSOLIDATED STATEMENTS OF COMPREHENSIVE iNCOME / LOSS Statements 5 false false R6.htm 1004000 - Statement - CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY Sheet http://www.assertiotx.com/role/ConsolidatedStatementsOfShareholdersEquity CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY Statements 6 false false R7.htm 1005000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS Sheet http://www.assertiotx.com/role/ConsolidatedStatementsOfCashFlows CONSOLIDATED STATEMENTS OF CASH FLOWS Statements 7 false false R8.htm 2101100 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPolicies ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Notes 8 false false R9.htm 2102100 - Disclosure - LICENSE AND COLLABORATIVE ARRANGEMENTS Sheet http://www.assertiotx.com/role/LicenseAndCollaborativeArrangements LICENSE AND COLLABORATIVE ARRANGEMENTS Notes 9 false false R10.htm 2103100 - Disclosure - CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS Sheet http://www.assertiotx.com/role/CashCashEquivalentsAndShortTermInvestments CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS Notes 10 false false R11.htm 2104100 - Disclosure - REVENUE Sheet http://www.assertiotx.com/role/Revenue REVENUE Notes 11 false false R12.htm 2105100 - Disclosure - ACCOUNTS RECEIVABLES, NET Sheet http://www.assertiotx.com/role/AccountsReceivablesNet ACCOUNTS RECEIVABLES, NET Notes 12 false false R13.htm 2106100 - Disclosure - INVENTORIES Sheet http://www.assertiotx.com/role/Inventories INVENTORIES Notes 13 false false R14.htm 2107100 - Disclosure - PROPERTY AND EQUIPMENT Sheet http://www.assertiotx.com/role/PropertyAndEquipment PROPERTY AND EQUIPMENT Notes 14 false false R15.htm 2108100 - Disclosure - INTANGIBLE ASSETS Sheet http://www.assertiotx.com/role/IntangibleAssets INTANGIBLE ASSETS Notes 15 false false R16.htm 2109100 - Disclosure - ACCRUED LIABILITIES Sheet http://www.assertiotx.com/role/AccruedLiabilities ACCRUED LIABILITIES Notes 16 false false R17.htm 2110100 - Disclosure - DEBT Sheet http://www.assertiotx.com/role/Debt DEBT Notes 17 false false R18.htm 2111100 - Disclosure - RESTRUCTURING CHARGES Sheet http://www.assertiotx.com/role/RestructuringCharges RESTRUCTURING CHARGES Notes 18 false false R19.htm 2112100 - Disclosure - COMMITMENTS AND CONTINGENCIES Sheet http://www.assertiotx.com/role/CommitmentsAndContingencies COMMITMENTS AND CONTINGENCIES Notes 19 false false R20.htm 2113100 - Disclosure - STOCK-BASED COMPENSATION Sheet http://www.assertiotx.com/role/StockBasedCompensation STOCK-BASED COMPENSATION Notes 20 false false R21.htm 2114100 - Disclosure - SHAREHOLDERS' EQUITY Sheet http://www.assertiotx.com/role/ShareholdersEquity SHAREHOLDERS' EQUITY Notes 21 false false R22.htm 2115100 - Disclosure - NET INCOME (LOSS) PER SHARE Sheet http://www.assertiotx.com/role/NetIncomeLossPerShare NET INCOME (LOSS) PER SHARE Notes 22 false false R23.htm 2116100 - Disclosure - ACQUISITIONS AND DISPOSITIONS Sheet http://www.assertiotx.com/role/AcquisitionsAndDispositions ACQUISITIONS AND DISPOSITIONS Notes 23 false false R24.htm 2117100 - Disclosure - INCOME TAXES Sheet http://www.assertiotx.com/role/IncomeTaxes INCOME TAXES Notes 24 false false R25.htm 2118100 - Disclosure - SUBSEQUENT EVENTS Sheet http://www.assertiotx.com/role/SubsequentEvents SUBSEQUENT EVENTS Notes 25 false false R26.htm 2119100 - Disclosure - SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) Sheet http://www.assertiotx.com/role/SelectedQuarterlyFinancialDataUnaudited SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) Notes 26 false false R27.htm 2120100 - Schedule - SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS Sheet http://www.assertiotx.com/role/ScheduleIiValuationAndQualifyingAccounts SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS Uncategorized 27 false false R28.htm 2201201 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesPolicies ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies) Uncategorized 28 false false R29.htm 2301302 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesTables ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables) Uncategorized 29 false false R30.htm 2303301 - Disclosure - CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS (Tables) Sheet http://www.assertiotx.com/role/CashCashEquivalentsAndShortTermInvestmentsTables CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS (Tables) Uncategorized 30 false false R31.htm 2304301 - Disclosure - REVENUE (Tables) Sheet http://www.assertiotx.com/role/RevenueTables REVENUE (Tables) Uncategorized 31 false false R32.htm 2305301 - Disclosure - ACCOUNTS RECEIVABLES, NET (Tables) Sheet http://www.assertiotx.com/role/AccountsReceivablesNetTables ACCOUNTS RECEIVABLES, NET (Tables) Uncategorized 32 false false R33.htm 2306301 - Disclosure - INVENTORIES (Tables) Sheet http://www.assertiotx.com/role/InventoriesTables INVENTORIES (Tables) Uncategorized 33 false false R34.htm 2307301 - Disclosure - PROPERTY AND EQUIPMENT (Tables) Sheet http://www.assertiotx.com/role/PropertyAndEquipmentTables PROPERTY AND EQUIPMENT (Tables) Uncategorized 34 false false R35.htm 2308301 - Disclosure - INTANGIBLE ASSETS (Tables) Sheet http://www.assertiotx.com/role/IntangibleAssetsTables INTANGIBLE ASSETS (Tables) Uncategorized 35 false false R36.htm 2309301 - Disclosure - ACCRUED LIABILITIES (Tables) Sheet http://www.assertiotx.com/role/AccruedLiabilitiesTables ACCRUED LIABILITIES (Tables) Uncategorized 36 false false R37.htm 2310301 - Disclosure - DEBT (Tables) Sheet http://www.assertiotx.com/role/DebtTables DEBT (Tables) Uncategorized 37 false false R38.htm 2311301 - Disclosure - RESTRUCTURING CHARGES (Tables) Sheet http://www.assertiotx.com/role/RestructuringChargesTables RESTRUCTURING CHARGES (Tables) Uncategorized 38 false false R39.htm 2312301 - Disclosure - COMMITMENTS AND CONTINGENCIES (Tables) Sheet http://www.assertiotx.com/role/CommitmentsAndContingenciesTables COMMITMENTS AND CONTINGENCIES (Tables) Uncategorized 39 false false R40.htm 2313301 - Disclosure - STOCK-BASED COMPENSATION (Tables) Sheet http://www.assertiotx.com/role/StockBasedCompensationTables STOCK-BASED COMPENSATION (Tables) Uncategorized 40 false false R41.htm 2315301 - Disclosure - NET INCOME (LOSS) PER SHARE (Tables) Sheet http://www.assertiotx.com/role/NetIncomeLossPerShareTables NET INCOME (LOSS) PER SHARE (Tables) Uncategorized 41 false false R42.htm 2317301 - Disclosure - INCOME TAXES (Tables) Sheet http://www.assertiotx.com/role/IncomeTaxesTables INCOME TAXES (Tables) Uncategorized 42 false false R43.htm 2319301 - Disclosure - SELECTED QUARTERLY FINANCIAL DATA (UNADUITED) (Tables) Sheet http://www.assertiotx.com/role/SelectedQuarterlyFinancialDataUnaduitedTables SELECTED QUARTERLY FINANCIAL DATA (UNADUITED) (Tables) Uncategorized 43 false false R44.htm 2401403 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Organization (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesOrganizationDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Organization (Details) Uncategorized 44 false false R45.htm 2401404 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Principles of Consolidation (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesPrinciplesOfConsolidationDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Principles of Consolidation (Details) Uncategorized 45 false false R46.htm 2401405 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Investments (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesInvestmentsDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Investments (Details) Uncategorized 46 false false R47.htm 2401406 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) Uncategorized 47 false false R48.htm 2401407 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesRevenueRecognitionDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition (Details) Uncategorized 48 false false R49.htm 2401408 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Advertising Costs (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesAdvertisingCostsDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Advertising Costs (Details) Uncategorized 49 false false R50.htm 2401409 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment Information (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesSegmentInformationDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment Information (Details) Uncategorized 50 false false R51.htm 2401410 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Risk (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesConcentrationOfRiskDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Risk (Details) Uncategorized 51 false false R52.htm 2401411 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Product Shipments and Accounts Receivable, By Distributor (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesScheduleOfProductShipmentsAndAccountsReceivableByDistributorDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Product Shipments and Accounts Receivable, By Distributor (Details) Uncategorized 52 false false R53.htm 2401412 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently Adopted and Issued Accounting Pronouncements (Details) Sheet http://www.assertiotx.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesRecentlyAdoptedAndIssuedAccountingPronouncementsDetails ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently Adopted and Issued Accounting Pronouncements (Details) Uncategorized 53 false false R54.htm 2402401 - Disclosure - LICENSE AND COLLABORATIVE ARRANGEMENTS - Narrative (Details) Sheet http://www.assertiotx.com/role/LicenseAndCollaborativeArrangementsNarrativeDetails LICENSE AND COLLABORATIVE ARRANGEMENTS - Narrative (Details) Uncategorized 54 false false R55.htm 2403402 - Disclosure - CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Summary of Securities Classifies as Cash and Cash Equivalents and Short-term Investments (Details) Sheet http://www.assertiotx.com/role/CashCashEquivalentsAndShortTermInvestmentsSummaryOfSecuritiesClassifiesAsCashAndCashEquivalentsAndShortTermInvestmentsDetails CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Summary of Securities Classifies as Cash and Cash Equivalents and Short-term Investments (Details) Uncategorized 55 false false R56.htm 2403403 - Disclosure - CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Narrative (Details) Sheet http://www.assertiotx.com/role/CashCashEquivalentsAndShortTermInvestmentsNarrativeDetails CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Narrative (Details) Uncategorized 56 false false R57.htm 2403404 - Disclosure - CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Schedule of Gross Unrealized Losses and Fair Value of Investments (Details) Sheet http://www.assertiotx.com/role/CashCashEquivalentsAndShortTermInvestmentsScheduleOfGrossUnrealizedLossesAndFairValueOfInvestmentsDetails CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Schedule of Gross Unrealized Losses and Fair Value of Investments (Details) Uncategorized 57 false false R58.htm 2403405 - Disclosure - CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Schedule of Fair Value Hierarchy for Financial Assets and Liabilities (Details) Sheet http://www.assertiotx.com/role/CashCashEquivalentsAndShortTermInvestmentsScheduleOfFairValueHierarchyForFinancialAssetsAndLiabilitiesDetails CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Schedule of Fair Value Hierarchy for Financial Assets and Liabilities (Details) Uncategorized 58 false false R59.htm 2403406 - Disclosure - CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Summary of Changes in Fair Value of All Financial Liabilities (Details) Sheet http://www.assertiotx.com/role/CashCashEquivalentsAndShortTermInvestmentsSummaryOfChangesInFairValueOfAllFinancialLiabilitiesDetails CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - Summary of Changes in Fair Value of All Financial Liabilities (Details) Uncategorized 59 false false R60.htm 2404402 - Disclosure - REVENUE - Schedule of Disaggregated Revenue from Contracts with Customers (Details) Sheet http://www.assertiotx.com/role/RevenueScheduleOfDisaggregatedRevenueFromContractsWithCustomersDetails REVENUE - Schedule of Disaggregated Revenue from Contracts with Customers (Details) Uncategorized 60 false false R61.htm 2404403 - Disclosure - REVENUE - Narrative (Details) Sheet http://www.assertiotx.com/role/RevenueNarrativeDetails REVENUE - Narrative (Details) Uncategorized 61 false false R62.htm 2404404 - Disclosure - REVENUE - Summary of Contract Assets and Liabilities (Details) Sheet http://www.assertiotx.com/role/RevenueSummaryOfContractAssetsAndLiabilitiesDetails REVENUE - Summary of Contract Assets and Liabilities (Details) Uncategorized 62 false false R63.htm 2405402 - Disclosure - ACCOUNTS RECEIVABLES, NET - Schedule of Accounts Receivable, Net (Details) Sheet http://www.assertiotx.com/role/AccountsReceivablesNetScheduleOfAccountsReceivableNetDetails ACCOUNTS RECEIVABLES, NET - Schedule of Accounts Receivable, Net (Details) Uncategorized 63 false false R64.htm 2406402 - Disclosure - INVENTORIES - Schedule of Inventories (Details) Sheet http://www.assertiotx.com/role/InventoriesScheduleOfInventoriesDetails INVENTORIES - Schedule of Inventories (Details) Uncategorized 64 false false R65.htm 2407402 - Disclosure - PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Details) Sheet http://www.assertiotx.com/role/PropertyAndEquipmentScheduleOfPropertyAndEquipmentDetails PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Details) Uncategorized 65 false false R66.htm 2407403 - Disclosure - PROPERTY AND EQUIPMENT - Narrative (Details) Sheet http://www.assertiotx.com/role/PropertyAndEquipmentNarrativeDetails PROPERTY AND EQUIPMENT - Narrative (Details) Uncategorized 66 false false R67.htm 2408402 - Disclosure - INTANGIBLE ASSETS - Schedule of Gross Carrying Amounts and Net Book Value Intangible Assets (Details) Sheet http://www.assertiotx.com/role/IntangibleAssetsScheduleOfGrossCarryingAmountsAndNetBookValueIntangibleAssetsDetails INTANGIBLE ASSETS - Schedule of Gross Carrying Amounts and Net Book Value Intangible Assets (Details) Uncategorized 67 false false R68.htm 2408403 - Disclosure - INTANGIBLE ASSETS - Schedule of Future Amortization Expenses (Details) Sheet http://www.assertiotx.com/role/IntangibleAssetsScheduleOfFutureAmortizationExpensesDetails INTANGIBLE ASSETS - Schedule of Future Amortization Expenses (Details) Uncategorized 68 false false R69.htm 2409402 - Disclosure - ACCRUED LIABILITIES - Schedule of Accrued Liabilities (Details) Sheet http://www.assertiotx.com/role/AccruedLiabilitiesScheduleOfAccruedLiabilitiesDetails ACCRUED LIABILITIES - Schedule of Accrued Liabilities (Details) Uncategorized 69 false false R70.htm 2410402 - Disclosure - DEBT - Narrative (Details) Sheet http://www.assertiotx.com/role/DebtNarrativeDetails DEBT - Narrative (Details) Uncategorized 70 false false R71.htm 2410403 - Disclosure - DEBT - Schedule of Principal Amounts of Senior Notes Repayable (Details) Notes http://www.assertiotx.com/role/DebtScheduleOfPrincipalAmountsOfSeniorNotesRepayableDetails DEBT - Schedule of Principal Amounts of Senior Notes Repayable (Details) Uncategorized 71 false false R72.htm 2410404 - Disclosure - DEBT - Summary of Carrying Value of Senior Notes (Details) Notes http://www.assertiotx.com/role/DebtSummaryOfCarryingValueOfSeniorNotesDetails DEBT - Summary of Carrying Value of Senior Notes (Details) Uncategorized 72 false false R73.htm 2410405 - Disclosure - DEBT - Summary of Interest Expense of Senior Notes (Details) Notes http://www.assertiotx.com/role/DebtSummaryOfInterestExpenseOfSeniorNotesDetails DEBT - Summary of Interest Expense of Senior Notes (Details) Uncategorized 73 false false R74.htm 2410406 - Disclosure - DEBT - Summary of Liability Component of Convertible Notes (Details) Notes http://www.assertiotx.com/role/DebtSummaryOfLiabilityComponentOfConvertibleNotesDetails DEBT - Summary of Liability Component of Convertible Notes (Details) Uncategorized 74 false false R75.htm 2410407 - Disclosure - DEBT - Summary of Interest Expense of Convertible Notes (Details) Notes http://www.assertiotx.com/role/DebtSummaryOfInterestExpenseOfConvertibleNotesDetails DEBT - Summary of Interest Expense of Convertible Notes (Details) Uncategorized 75 false false R76.htm 2411402 - Disclosure - RESTRUCTURING CHARGES - Narrative (Details) Sheet http://www.assertiotx.com/role/RestructuringChargesNarrativeDetails RESTRUCTURING CHARGES - Narrative (Details) Uncategorized 76 false false R77.htm 2411403 - Disclosure - RESTRUCTURING CHARGES - Schedule of Restructuring Activities (Details) Sheet http://www.assertiotx.com/role/RestructuringChargesScheduleOfRestructuringActivitiesDetails RESTRUCTURING CHARGES - Schedule of Restructuring Activities (Details) Uncategorized 77 false false R78.htm 2411404 - Disclosure - RESTRUCTURING CHARGES - Schedule of Accrued Restructuring and Severance Costs (Details) Sheet http://www.assertiotx.com/role/RestructuringChargesScheduleOfAccruedRestructuringAndSeveranceCostsDetails RESTRUCTURING CHARGES - Schedule of Accrued Restructuring and Severance Costs (Details) Uncategorized 78 false false R79.htm 2412402 - Disclosure - COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Lease Payments (Details) Sheet http://www.assertiotx.com/role/CommitmentsAndContingenciesScheduleOfFutureMinimumLeasePaymentsDetails COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Lease Payments (Details) Uncategorized 79 false false R80.htm 2412403 - Disclosure - COMMITMENTS AND CONTINGENCIES - Leases (Details) Sheet http://www.assertiotx.com/role/CommitmentsAndContingenciesLeasesDetails COMMITMENTS AND CONTINGENCIES - Leases (Details) Uncategorized 80 false false R81.htm 2412404 - Disclosure - COMMITMENTS AND CONTINGENCIES - Legal Matters (Details) Sheet http://www.assertiotx.com/role/CommitmentsAndContingenciesLegalMattersDetails COMMITMENTS AND CONTINGENCIES - Legal Matters (Details) Uncategorized 81 false false R82.htm 2413402 - Disclosure - STOCK-BASED COMPENSATION - Schedule of Stock-Based Compensation Expense (Details) Sheet http://www.assertiotx.com/role/StockBasedCompensationScheduleOfStockBasedCompensationExpenseDetails STOCK-BASED COMPENSATION - Schedule of Stock-Based Compensation Expense (Details) Uncategorized 82 false false R83.htm 2413403 - Disclosure - STOCK-BASED COMPENSATION - Stock Options Narrative and Activity (Details) Sheet http://www.assertiotx.com/role/StockBasedCompensationStockOptionsNarrativeAndActivityDetails STOCK-BASED COMPENSATION - Stock Options Narrative and Activity (Details) Uncategorized 83 false false R84.htm 2413404 - Disclosure - STOCK-BASED COMPENSATION - Schedule of Fair Value Assumptions (Details) Sheet http://www.assertiotx.com/role/StockBasedCompensationScheduleOfFairValueAssumptionsDetails STOCK-BASED COMPENSATION - Schedule of Fair Value Assumptions (Details) Uncategorized 84 false false R85.htm 2413405 - Disclosure - STOCK-BASED COMPENSATION - Equity Match Program (Details) Sheet http://www.assertiotx.com/role/StockBasedCompensationEquityMatchProgramDetails STOCK-BASED COMPENSATION - Equity Match Program (Details) Uncategorized 85 false false R86.htm 2413406 - Disclosure - STOCK-BASED COMPENSATION - Restricted Stock Units Narrative and Activity (Details) Sheet http://www.assertiotx.com/role/StockBasedCompensationRestrictedStockUnitsNarrativeAndActivityDetails STOCK-BASED COMPENSATION - Restricted Stock Units Narrative and Activity (Details) Uncategorized 86 false false R87.htm 2414401 - Disclosure - SHAREHOLDERS' EQUITY - Narrative (Details) Sheet http://www.assertiotx.com/role/ShareholdersEquityNarrativeDetails SHAREHOLDERS' EQUITY - Narrative (Details) Uncategorized 87 false false R88.htm 2415402 - Disclosure - NET INCOME (LOSS) PER SHARE - Schedule of Basic and Diluted Earnings Per Share (Details) Sheet http://www.assertiotx.com/role/NetIncomeLossPerShareScheduleOfBasicAndDilutedEarningsPerShareDetails NET INCOME (LOSS) PER SHARE - Schedule of Basic and Diluted Earnings Per Share (Details) Uncategorized 88 false false R89.htm 2415403 - Disclosure - NET INCOME (LOSS) PER SHARE - Schedule of Anti-Dilutive Shares (Details) Sheet http://www.assertiotx.com/role/NetIncomeLossPerShareScheduleOfAntiDilutiveSharesDetails NET INCOME (LOSS) PER SHARE - Schedule of Anti-Dilutive Shares (Details) Uncategorized 89 false false R90.htm 2416401 - Disclosure - ACQUISITIONS AND DISPOSITIONS - Narrative (Details) Sheet http://www.assertiotx.com/role/AcquisitionsAndDispositionsNarrativeDetails ACQUISITIONS AND DISPOSITIONS - Narrative (Details) Uncategorized 90 false false R91.htm 2417402 - Disclosure - INCOME TAXES - Schedule of (Benefit) Provision for Income Taxes (Details) Sheet http://www.assertiotx.com/role/IncomeTaxesScheduleOfBenefitProvisionForIncomeTaxesDetails INCOME TAXES - Schedule of (Benefit) Provision for Income Taxes (Details) Uncategorized 91 false false R92.htm 2417403 - Disclosure - INCOME TAXES - Schedule of Effective Income Tax Reconciliation (Details) Sheet http://www.assertiotx.com/role/IncomeTaxesScheduleOfEffectiveIncomeTaxReconciliationDetails INCOME TAXES - Schedule of Effective Income Tax Reconciliation (Details) Uncategorized 92 false false R93.htm 2417404 - Disclosure - INCOME TAXES - Narrative (Details) Sheet http://www.assertiotx.com/role/IncomeTaxesNarrativeDetails INCOME TAXES - Narrative (Details) Uncategorized 93 false false R94.htm 2417405 - Disclosure - INCOME TAXES - Schedule of Deferred Tax Assets and Deferred Tax Liabilities (Details) Sheet http://www.assertiotx.com/role/IncomeTaxesScheduleOfDeferredTaxAssetsAndDeferredTaxLiabilitiesDetails INCOME TAXES - Schedule of Deferred Tax Assets and Deferred Tax Liabilities (Details) Uncategorized 94 false false R95.htm 2417406 - Disclosure - INCOME TAXES - Schedule of Unrecognized Tax Benefits (Details) Sheet http://www.assertiotx.com/role/IncomeTaxesScheduleOfUnrecognizedTaxBenefitsDetails INCOME TAXES - Schedule of Unrecognized Tax Benefits (Details) Uncategorized 95 false false R96.htm 2418401 - Disclosure - SUBSEQUENT EVENTS - Narrative (Details) Sheet http://www.assertiotx.com/role/SubsequentEventsNarrativeDetails SUBSEQUENT EVENTS - Narrative (Details) Uncategorized 96 false false R97.htm 2419402 - Disclosure - SELECTED QUARTERLY FINANCIAL DATA (UNADUITED) - Schedule of Quarterly Financial Information (Details) Sheet http://www.assertiotx.com/role/SelectedQuarterlyFinancialDataUnaduitedScheduleOfQuarterlyFinancialInformationDetails SELECTED QUARTERLY FINANCIAL DATA (UNADUITED) - Schedule of Quarterly Financial Information (Details) Uncategorized 97 false false R98.htm 2420401 - Disclosure - SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS (Details) Sheet http://www.assertiotx.com/role/ScheduleIiValuationAndQualifyingAccountsDetails SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS (Details) Uncategorized 98 false false R9999.htm Uncategorized Items - asrt-20181231.xml Sheet http://xbrl.sec.gov/role/uncategorizedFacts Uncategorized Items - asrt-20181231.xml Cover 99 false false All Reports Book All Reports asrt-20181231.xml asrt-20181231.xsd asrt-20181231_cal.xml asrt-20181231_def.xml asrt-20181231_lab.xml asrt-20181231_pre.xml http://fasb.org/us-gaap/2018-01-31 http://xbrl.sec.gov/dei/2018-01-31 http://fasb.org/srt/2018-01-31 true true