XML 89 R71.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Variable Interest Entities - Narrative (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 USD ($) Investment | Dec. 31, 2016 USD ($) Investment | Dec. 31, 2015 USD ($)
Variable Interest Entity [Line Items] |  |  |
Number of investments in VIEs | Investment | 2 | 3 |
Proceeds from sale of equity method investments | $ (9.3) | $ 0.0 | $ 0.0
Chaspark |  |  |
Variable Interest Entity [Line Items] |  |  |
Proceeds from sale of equity method investments | $ (9.3) |  |

X
- Definition Number Of Investments In Variable Interest Entities + References No definition available. + Details
Name: | ahl_NumberOfInvestmentsInVariableInterestEntities
Namespace Prefix: | ahl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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_VariableInterestEntityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ahl_ChasparkMaritimeHoldingsLtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |