XML 87 R65.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Convertible Securities - Additional Information (Details) - Junior Convertible Securities | Aug. 10, 2018 USD ($) trading_day $ / shares | Aug. 09, 2018 | Dec. 31, 2018 USD ($)
--- | --- | --- | ---
Debt Instrument |  |  |
Stated interest rate |  |  | 5.15%
Principal amount at maturity | $ | $ 50.00 |  |
Conversion ratio (in shares) | 0.2525 | 0.2500 |
Conversion price (in usd per share) | $ / shares | $ 198.02 |  |
Redemption closing price trigger (in usd per share) | $ / shares | $ 257.43 |  |
Number of trading days closing price has exceeded threshold | trading_day | 20 |  |
Number of consecutive trading days | trading_day | 30 |  |
Deferred tax liability | $ |  |  | $ 7,800,000

X
- Definition Debt Instrument, Individual Security, Face Amount + References No definition available. + Details
Name: | amg_DebtInstrumentIndividualSecurityFaceAmount
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the deferred taxes generated from the excess of the interest expense calculated under federal income tax regulations over interest expense as calculated for book purposes. + References No definition available. + Details
Name: | amg_DeferredTaxLiabilityFromExcessInterestExpenseCalculation
Namespace Prefix: | amg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The price per share of the conversion feature embedded in the debt instrument. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031898-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(5)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionRatio1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Price of the entity's common stock which would be required to be attained for the conversion feature embedded in the debt instrument to become effective. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentConvertibleStockPriceTrigger
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentConvertibleThresholdTradingDays
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | us-gaap_DebtInstrumentAxis=amg_JuniorConvertibleTrustPreferredSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |