Deferred Acquisition Costs, Deferred Sales Inducements, and Value of Business Acquired - Roll Forward of DAC, DSI, and VOBA (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
DAC
Beginning balance	$ 707	$ 425	$ 210
Additions	601	288	250
Unlocking	(12)	(6)	2
Amortization	(110)	(34)	(20)
Impact of unrealized investment (gains) losses	(38)	34	(17)
Ending balance	1,148	707	425
DSI
Beginning balance	321	188	91
Additions	200	136	113
Unlocking	(3)	(2)	6
Amortization	(37)	(18)	(10)
Impact of unrealized investment (gains) losses	(19)	17	(12)
Ending balance	462	321	188
VOBA
Beginning balance	1,635	1,616	1,834
Additions	0	0	0
Unlocking	(23)	(27)	28
Amortization	(159)	(136)	(129)
Impact of unrealized investment (gains) losses	(99)	182	(117)
Ending balance	1,354	1,635	1,616
Total
Beginning balance	2,663	2,229	2,135
Additions	801	424	363
Unlocking	(38)	(35)	36
Amortization	(306)	(188)	(159)
Impact of unrealized investment (gains) losses	(156)	233	(146)
Ending balance	$ 2,964	$ 2,663	$ 2,229

Deferred Policy Acquisition Costs, Deferred Sales Inducements, and Present Value of Future Profits

No definition available.

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

- Definition

Deferred Policy Acquisition Costs, Deferred Sales Inducements, and Present Value of Future Profits, Additions

+ References

No definition available.

+ Details

Name:	ahl_DeferredPolicyAcquisitionCostsDeferredSalesInducementsandPresentValueofFutureProfitsAdditions
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Deferred Policy Acquisition Costs, Deferred Sales Inducements, and Present Value of Future Profits, Amortization Expense Excluding Unlocking

+ References

No definition available.

+ Details

Name:	ahl_DeferredPolicyAcquisitionCostsDeferredSalesInducementsandPresentValueofFutureProfitsAmortizationExpenseExcludingUnlocking
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Deferred Policy Acquisition Costs, Deferred Sales Inducements, and Present Value of Future Profits, Amortization Expense Unlocking

+ References

No definition available.

+ Details

Name:	ahl_DeferredPolicyAcquisitionCostsDeferredSalesInducementsandPresentValueofFutureProfitsAmortizationExpenseUnlocking
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Deferred Policy Acquisition Costs, Deferred Sales Inducements, and Present Value of Future Profits [Roll Forward]

+ References

No definition available.

+ Details

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

- Definition

Deferred Policy Acquisition Costs, Deferred Sales Inducements, and Present Value of Future Profits, Unrealized Investment Gains (Losses)

+ References

No definition available.

+ Details

Name:	ahl_DeferredPolicyAcquisitionCostsDeferredSalesInducementsandPresentValueofFutureProfitsUnrealizedInvestmentGainsLosses
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Deferred Sales Inducements, Amortization Expense Excluding Unlocking

+ References

No definition available.

+ Details

Name:	ahl_DeferredSalesInducementsAmortizationExpenseExcludingUnlocking
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) to amortization expense of deferred sales inducements (DSI) due to assumption change.

+ References

No definition available.

+ Details

Name:	ahl_DeferredSalesInducementsAmortizationExpenseUnlocking
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of unrealized investment gain (loss) which decreases (increases) deferred sales inducements.

+ References

No definition available.

+ Details

Name:	ahl_DeferredSalesInducementsUnrealizedInvestmentGainsLosses
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Present Value of Future Insurance Profits, Amortization Expense Excluding Unlocking

+ References

No definition available.

+ Details

Name:	ahl_PresentValueofFutureInsuranceProfitsAmortizationExpenseExcludingUnlocking
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) to amortization expense of value of business acquired (VOBA) due to assumption change.

+ References

No definition available.

+ Details

Name:	ahl_PresentValueofFutureInsuranceProfitsAmortizationExpenseUnlocking
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of unrealized investment gain (loss) which decreases (increases) value of business acquired.

+ References

No definition available.

+ Details

Name:	ahl_PresentValueofFutureInsuranceProfitsUnrealizedInvestmentGainsLosses
Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) to amortization expense of deferred policy acquisition cost (DAC) due to assumption change.

+ References

No definition available.

+ Details

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

- Definition

Amount of other increase (decrease) to amortization expense of deferred policy acquisition cost (DAC).

+ References

No definition available.

+ Details

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

- Definition

Amount of unrealized investment gain (loss) which decreases (increases) deferred policy acquisition cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 35
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=49177698&loc=d3e10138-158409

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=35755530&loc=d3e11264-158415

+ Details

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

- Definition

Net amount of deferred policy acquisition costs capitalized on contracts remaining in force as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 825
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6487548&loc=d3e32546-158582

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 55
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68057816&loc=d3e11446-158418

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-18(Column B))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e575016-122915

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6481648&loc=d3e11198-158413

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-16(Column B))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574960-122915

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(7))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Total amount of policy acquisition costs capitalized during the income statement period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35755530&loc=d3e11264-158415

+ Details

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

- Definition

The amount of deferred sales inducement costs capitalized during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6481800&loc=d3e11332-158416

+ Details

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

- Definition

The unamortized carrying amount of deferred sales inducement costs as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6481800&loc=d3e11332-158416

+ Details

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

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_MovementInDeferredSalesInducementsRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_MovementInPresentValueOfFutureInsuranceProfitsRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Additions in present value of future profits asset during the year arising from acquisitions of insurance entities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section S99
-Paragraph 2
-Subparagraph (2)
-URI http://asc.fasb.org/extlink&oid=27015749&loc=d3e569990-122904

+ Details

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

- Definition

The remaining unamortized carrying amount as of the balance sheet date of expected future earnings from insurance contracts acquired (also known as present value of future profits).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section S99
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=27015749&loc=d3e569990-122904

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.10)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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