XML 84 R74.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Commitments and Contingent Liabilities - Schedule of Company's Restricted Assets (Details) - USD ($) $ in Millions | Sep. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items] |  |
Total restricted assets | $ 4,537.6 | $ 4,535.7
Total as percent of investable assets(1) | 51.90% | 49.30%
Letters of credit / guarantees |  |
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items] |  |
Total restricted assets | $ 694.6 | $ 672.1
Affiliated transactions |  |
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items] |  |
Total restricted assets | 1,438.7 | 1,482.8
Third party |  |
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items] |  |
Total restricted assets | $ 2,404.3 | $ 2,380.8

X
- Definition Percentage of cash and invested assets. + References No definition available. + Details
Name: | ahl_CashAndInvestedAssetsPercent
Namespace Prefix: | ahl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Restricted assets. + References No definition available. + Details
Name: | ahl_RestrictedAssets
Namespace Prefix: | ahl_
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_ScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_AffiliatedEntityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ahl_ThirdPartyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |