XML 142 R65.htm IDEA: XBRL DOCUMENT v3.22.1

Investments - Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Available for Sale Investments in Fixed Income Maturities and Short-Term Investments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	$ 4,881.6	$ 4,348.1
Gross unrealized gains	95.3	222.4
Gross unrealized losses	(34.5)	(0.8)
Allowance for credit loss	(2.7)	0.2
Fixed income securities, available for sale amortized cost	4,823.5	4,126.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3.6	0.2
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	34.5	1.0
0-12 months, Fair Market Value	2,014.6	147.8
Total short-term investments — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	10.1	87.8
Gross unrealized gains	0.0	0.0
Gross unrealized losses	0.0	(0.2)
Allowance for credit loss	0.0	0.0
Fixed income securities, available for sale amortized cost	10.1	88.0
Total fixed income securities — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	4,891.7	4,435.9
Gross unrealized gains	95.3	222.4
Gross unrealized losses	(34.5)	(1.0)
Allowance for credit loss	(2.7)	0.2
Fixed income securities, available for sale amortized cost	4,833.6	4,214.7
Fixed income securities — Available for sale
Schedule of Trading Securities and Other Trading Items [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3.6	0.0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	34.5	0.8
0-12 months, Fair Market Value	2,010.2	139.1
Short-term investments
Schedule of Trading Securities and Other Trading Items [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0	0.2
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	0.0	0.2
0-12 months, Fair Market Value	4.4	8.7
U.S. government
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	1,084.3	1,101.2
Gross unrealized gains	24.0	60.5
Gross unrealized losses	(5.9)	(0.6)
Allowance for credit loss	0.0	0.0
Fixed income securities, available for sale amortized cost	1,066.2	1,041.3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1.9	0.0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	5.9	0.6
0-12 months, Fair Market Value	309.1	58.7
U.S. agency
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	21.5	34.3
Gross unrealized gains	0.8	1.5
Gross unrealized losses	0.0	0.0
Allowance for credit loss	0.0	0.0
Fixed income securities, available for sale amortized cost	20.7	32.8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	0.0
0-12 months, Fair Market Value	6.1
Municipal
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	82.6	67.1
Gross unrealized gains	2.0	5.5
Gross unrealized losses	(0.5)	0.0
Allowance for credit loss	(0.1)	0.0
Fixed income securities, available for sale amortized cost	81.2	61.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	0.5
0-12 months, Fair Market Value	29.7
Corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	2,208.3	1,826.2
Gross unrealized gains	47.5	112.0
Gross unrealized losses	(13.0)	(0.1)
Allowance for credit loss	(2.3)	0.2
Fixed income securities, available for sale amortized cost	2,176.1	1,714.5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1.3	0.0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	13.0	0.1
0-12 months, Fair Market Value	804.6	39.6
Non-U.S. government-backed corporate
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	136.8	63.4
Gross unrealized gains	0.2	0.7
Gross unrealized losses	(1.9)	0.0
Allowance for credit loss	0.0	0.0
Fixed income securities, available for sale amortized cost	138.5	62.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1.9
0-12 months, Fair Market Value	114.4
Non-U.S government
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	250.7	273.1
Gross unrealized gains	1.4	4.3
Gross unrealized losses	(1.2)	0.0
Allowance for credit loss	(0.3)	0.0
Fixed income securities, available for sale amortized cost	250.8	268.8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.0	0.0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1.2	0.0
0-12 months, Fair Market Value	181.8	7.5
Asset-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	0.5	2.3
Gross unrealized gains	0.0	0.0
Gross unrealized losses	0.0	0.0
Allowance for credit loss	0.0	0.0
Fixed income securities, available for sale amortized cost	0.5	2.3
Non-agency commercial mortgage-backed securities
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	6.9	7.4
Gross unrealized gains	0.3	0.7
Gross unrealized losses	0.0	0.0
Allowance for credit loss	0.0	0.0
Fixed income securities, available for sale amortized cost	6.6	6.7
Agency mortgage-backed
Schedule of Trading Securities and Other Trading Items [Line Items]
Fair market value	1,090.0	973.1
Gross unrealized gains	19.1	37.2
Gross unrealized losses	(12.0)	(0.1)
Allowance for credit loss	0.0	0.0
Fixed income securities, available for sale amortized cost	1,082.9	936.0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0.4	0.0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	12.0	0.1
0-12 months, Fair Market Value	$ 564.5	$ 33.3

X

- Definition

Debt Securities, Available for Sale Continuous Unrealized Loss Position Less Than Twelve Months Fair Market Value

+ References

No definition available.

+ Details

Name:	ahl_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsFairMarketValue
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

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

X

- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

+ Details

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

X

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922888-210455

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_FixedMaturitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_AvailableforsaleSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ForeignCorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=ahl_NonagencycommercialmortgagebackedsecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: