XML 49 R39.htm IDEA: XBRL DOCUMENT
v3.23.3

Investment Securities - Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract] |  |  |  |
Unrealized gain (loss) on investment securities held at the end of the period | $ (3,901) | $ (6,675) | $ 6,458 | $ (24,145)
Consolidated Entity Excluding Variable Interest Entities (VIE) |  |  |  |
Marketable Securities [Line Items] |  |  |  |
Other net investment gain (loss) | (2,152) | (5,563) | 11,329 | (23,729)
Seed Investments |  |  |  |
Marketable Securities [Line Items] |  |  |  |
Other net investment gain (loss) | 214 | (1,649) | 1,424 | (4,585)
Long-Term Cash Awards |  |  |  |
Marketable Securities [Line Items] |  |  |  |
Other net investment gain (loss) |  | (3,987) |  | (19,192)
Other |  |  |  |
Marketable Securities [Line Items] |  |  |  |
Other net investment gain (loss) | $ 2,088 | $ 73 | $ 3,778 | $ 48

X
- Definition Amount of realized and unrealized gain (loss) on investment. + References Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c),9(a)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2 + Details
Name: | us-gaap_GainLossOnInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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_MarketableSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of unrealized gain (loss) on investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 + Details
Name: | us-gaap_UnrealizedGainLossOnInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_ConsolidatedEntityExcludingVariableInterestEntitiesVIEMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=apam_SeedInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=apam_LongTermCashAwardsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=apam_OtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |