Name:	apam_ApproximatePercentageOfEarningsNotSubjectToIncomeTaxes
Namespace Prefix:	apam_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the expected payment date for payments made under the TRA, which is defined as the number of days from the date APAM's federal income tax return is filed for each fiscal year.

No definition available.

Name:	apam_TaxReceivableAgreementPaymentPeriod
Namespace Prefix:	apam_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Portion of the applicable cash savings, if any, in U.S. federal and state income tax that APAM actually realizes (or is deemed to realize in certain circumstances) to be paid to the holders of convertible preferred stock issued as consideration for the H&F Corp Merger (or Class A common stock issued upon conversion of that convertible preferred stock).

No definition available.

Name:	apam_TaxReceivableAgreementPercentageSavingsRequiredToBePaidToShareholders
Namespace Prefix:	apam_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Portion of the applicable cash savings, if any, in U.S. federal and state income tax that APAM actually realizes (or is deemed to realize in certain circumstances) retained by the entity.

No definition available.

Name:	apam_TaxReceivableAgreementPercentageToBeRetainedByEntity
Namespace Prefix:	apam_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Tax Receivable, Basis Point Spread on Variable Rate

No definition available.

Name:	apam_TaxReceivableBasisPointSpreadonVariableRate
Namespace Prefix:	apam_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Amount of income tax expense for which accounting for tax effect for remeasurement of deferred tax asset from change in tax rate is incomplete pursuant to Tax Cuts and Jobs Act and no reasonable estimate is determined.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2A
-Subparagraph (SAB Topic 5.EE.Q2(c))
-URI http://asc.fasb.org/extlink&oid=116825942&loc=SL116722634-122817

Name:	us-gaap_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateDeferredTaxAssetExistingIncomeTaxExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of statutory penalties accrued for a tax position claimed or expected to be claimed by the entity, in its tax return.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

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

The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319