XML 33 R79.htm IDEA: XBRL DOCUMENT
v3.20.1

Reinsurance - Additional Information (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 USD ($)
Reinsurance Disclosures [Abstract] |
Liability for unpaid claims and claims adjustment expense amount ceded | $ (125.5)

X
- Definition Liability For Unpaid Claims And Claims Adjustment Expense Amount Disposed of or Ceded + References No definition available. + Details
Name: | ahl_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAmountDisposedoforCeded
Namespace Prefix: | ahl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_ReinsuranceDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration