Number of claims filed industry-wide.

No definition available.

Name:	asrt_ClaimsNumberIndustryWideOpioid
Namespace Prefix:	asrt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of shareholder derivative actions that were filed.

+ References

No definition available.

+ Details

Name:	asrt_NumberOfShareholderDerivativeActionsFiled
Namespace Prefix:	asrt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_GainContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of entity's patents that another entity has allegedly infringed.

+ References

No definition available.

+ Details

Name:	us-gaap_GainContingencyPatentsAllegedlyInfringedUponNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount awarded from other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmountAwardedFromOtherParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of defendants named in a legal action.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingencyNumberOfDefendants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	srt_LitigationCaseAxis=asrt_OneHundredThirtyPatentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=asrt_CollectivelyActavisCollectivelyWatsonAndInceptaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=asrt_CompanyVs.PurdueCompaniesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationStatusAxis=us-gaap_SettledLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=asrt_SecuritiesClassActionLawsuitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=asrt_MultidistrictOpioidLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

COMMITMENTS AND CONTINGENCIES - Legal Matters (Details) $ in Millions	Jan. 30, 2019 USD ($)	Aug. 28, 2018 USD ($)	Aug. 23, 2017 action	Apr. 11, 2017 patent defendant	Mar. 09, 2016 patent	Dec. 31, 2019 USD ($) case	Dec. 31, 2018 USD ($)
Legal matters
Purchase obligation \| $						$ 2.4	$ 6.0
130 Patent
Legal matters
Number of patents infringed \| patent					3
Number of defendants \| defendant				4
Gralise ANDA Filers
Legal matters
Number of patents infringed \| patent				3
Number of defendants \| defendant				3
Company Vs. Purdue Companies \| Settled Litigation
Legal matters
Litigation settlement received \| $	$ 32.0	$ 30.0
Securities Class Action Lawsuit
Legal matters
Number of shareholder derivative actions filed \| action			5
Multidistrict Opioid Litigation \| Minimum
Legal matters
Number of industry-wide opioid litigation cases (more than) \| case						2,000