Equity Method Investment, Aggregate Cost [Roll Forward]

No definition available.

Name:	ahl_EquityMethodInvestmentAggregateCostRollForward
Namespace Prefix:	ahl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ 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 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Amount of gain (loss) on sale or disposal of an equity method investment.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(7)(c))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(9)(a))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

+ Details

Name:	us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This item represents the amount of unrealized intercompany profits and losses on transactions between the Entity and unconsolidated subsidiaries (including certain corporate joint ventures, and noncontrolled corporations), accounted for under the equity method of accounting, which have not been eliminated in preparing the Entity's financial statements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.3A-04)
-URI http://asc.fasb.org/extlink&oid=116822174&loc=d3e355119-122828

+ Details

Name:	us-gaap_EquityMethodInvestmentUnrealizedIntercompanyProfitLossNotEliminatedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The net cash outflow or inflow associated with the acquisition or sale of a business segment during the period.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

+ Details

Name:	us-gaap_PaymentsForProceedsFromBusinessesAndInterestInAffiliates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireEquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585

+ Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ahl_MVIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ahl_BeneAssicurazioniMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ahl_DigitalRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ahl_CropReMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ahl_MultiLineReinsurerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Investments - Other Investments (Details) - USD ($) $ in Millions			1 Months Ended	12 Months Ended
	Dec. 14, 2020	Jul. 26, 2016	Jan. 31, 2015	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance				$ 67.9	$ 67.1
Investment in the period				0.5	1.1
Unrealized gain/(loss) for the period				(0.7)	(0.3)
Equity method investment, realized gain (loss) on disposal				10.4
Proceeds from Sale of Equity Method Investments				(77.2)
Closing value of investment, ending balance				0.9	67.9	$ 67.1
MVI
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance				0.4	0.5
Investment in the period			$ 0.8	0.0	0.0	0.2	$ 0.1
Unrealized gain/(loss) for the period				(0.4)	(0.1)
Equity method investment, realized gain (loss) on disposal				0.0
Proceeds from Sale of Equity Method Investments				0.0
Closing value of investment, ending balance				0.0	0.4	0.5
Bene
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance				4.3	3.2
Investment in the period		$ 3.3
Equity method investment, cash payment				0.0	1.1	1.2
Unrealized gain/(loss) for the period				0.0	0.0
Equity method investment, realized gain (loss) on disposal				1.8
Proceeds from Sale of Equity Method Investments				(6.1)
Closing value of investment, ending balance				0.0	4.3	3.2
Digital Re
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance				0.7	0.9
Investment in the period				0.0	0.0
Unrealized gain/(loss) for the period				(0.3)	(0.2)
Equity method investment, realized gain (loss) on disposal				0.0
Proceeds from Sale of Equity Method Investments				0.0
Closing value of investment, ending balance				0.4	0.7	0.9
Crop Re
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance				62.5	62.5
Investment in the period				0.0	0.0
Unrealized gain/(loss) for the period				0.0	0.0
Equity method investment, realized gain (loss) on disposal	$ 71.1			8.6
Proceeds from Sale of Equity Method Investments				(71.1)
Closing value of investment, ending balance				0.0	62.5	62.5
Multi-Line Insurer
Equity Method Investment, Aggregate Cost [Roll Forward]
Opening undistributed value of investment, beginning balance				0.0	0.0
Investment in the period				0.5	0.0
Unrealized gain/(loss) for the period				0.0	0.0
Equity method investment, realized gain (loss) on disposal				0.0
Proceeds from Sale of Equity Method Investments				0.0
Closing value of investment, ending balance				$ 0.5	$ 0.0	$ 0.0