XML 133 R115.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Commitments and Contingencies - Additional Information (Details) £ in Millions, SGD in Millions, SFr in Millions, CAD in Millions, AUD in Millions, $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2017 USD ($) Investment | Dec. 31, 2016 USD ($) Investment | Dec. 31, 2017 SGD Investment | Dec. 31, 2017 AUD Investment | Dec. 31, 2017 CAD Investment | Dec. 31, 2017 CHF (SFr) Investment | Dec. 31, 2017 GBP (£) Investment | Dec. 31, 2016 SGD Investment | Dec. 31, 2016 AUD Investment | Dec. 31, 2016 CAD Investment | Dec. 31, 2016 CHF (SFr) Investment | Dec. 31, 2016 GBP (£) Investment
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Total as percent of investable assets | 53.40% | 49.30% |  |  |  |  |  |  |  |  |  |
Investable assets held by the Company | $ 8,700.0 | $ 9,200.0 |  |  |  |  |  |  |  |  |  |
Restricted assets | 4,638.8 | 4,535.7 |  |  |  |  |  |  |  |  |  |
Investable assets held by insurance regulators | $ 458.7 | 447.3 |  |  |  |  |  |  |  |  |  |
Minimum capital required | £ |  |  |  |  |  |  | £ 0.4 |  |  |  |  | £ 0.4
Percentage of reinsurance liabilities | 100.00% |  | 100.00% | 100.00% | 100.00% | 100.00% | 100.00% |  |  |  |  |
Reinsurance liabilities | $ 1,268.4 | 1,101.5 |  |  |  |  |  |  |  |  |  |
Assets held-in-trust | 1,350.9 | 1,351.2 |  |  |  |  |  |  |  |  |  |
Regulatory deposits | 6.0 | 6.0 |  |  |  |  |  |  |  |  |  |
Deposit with states | 6.1 | 6.0 |  |  |  |  |  |  |  |  |  |
Rental and premises expenses | 26.3 | 24.1 |  |  |  |  |  |  |  |  |  |
Depreciation for fixed assets | 34.6 | 22.6 |  |  |  |  |  |  |  |  |  |
Accumulated depreciation | $ 146.2 | $ 111.6 |  |  |  |  |  |  |  |  |  |
Number of investments | Investment | 2 | 3 | 2 | 2 | 2 | 2 | 2 | 3 | 3 | 3 | 3 | 3
Us Multi Beneficiary Trust Fund |  |  |  |  |  |  |  |  |  |  |  |
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Minimum trust fund | $ 20.0 |  |  |  |  |  |  |  |  |  |  |
Assets held-in-trust | 1,333.6 | $ 1,267.4 |  |  |  |  |  |  |  |  |  |
Us Surplus Lines Trust Fund |  |  |  |  |  |  |  |  |  |  |  |
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Assets held-in-trust | $ 195.0 | 185.7 |  |  |  |  |  |  |  |  |  |
Canadian Trust Fund |  |  |  |  |  |  |  |  |  |  |  |
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Assets held-in-trust | CAD |  |  |  |  | CAD 169.9 |  |  |  |  | CAD 249.2 |  |
Australian Trust Fund |  |  |  |  |  |  |  |  |  |  |  |
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Assets held-in-trust | AUD |  |  |  | AUD 198.7 |  |  |  |  | AUD 137.8 |  |  |
Swiss Trust Fund |  |  |  |  |  |  |  |  |  |  |  |
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Assets held-in-trust | SFr |  |  |  |  |  | SFr 9.8 |  |  |  |  | SFr 18.3 |
Singapore Trust Fund |  |  |  |  |  |  |  |  |  |  |  |
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Assets held-in-trust | SGD |  |  | SGD 120.6 |  |  |  |  | SGD 106.4 |  |  |  |
Bermuda |  |  |  |  |  |  |  |  |  |  |  |
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Percentage of reinsurance liabilities | 100.00% |  | 100.00% | 100.00% | 100.00% | 100.00% | 100.00% |  |  |  |  |
Reinsurance liabilities | $ 895.5 | 953.2 |  |  |  |  |  |  |  |  |  |
Real estate fund |  |  |  |  |  |  |  |  |  |  |  |
Restricted Cash And Collateral [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Restricted assets | $ 100.0 | $ 0.0 |  |  |  |  |  |  |  |  |  |

X
- Definition Accumulated depreciation. + References No definition available. + Details
Name: | ahl_AccumulatedDepreciation
Namespace Prefix: | ahl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Collateral funds held as percentage of cash and short term investments. + References No definition available. + Details
Name: | ahl_CollateralFundsHeldAsPercentageOfCashAndShortTermInvestments
Namespace Prefix: | ahl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Deposit with states. + References No definition available. + Details
Name: | ahl_DepositWithStates
Namespace Prefix: | ahl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Minimum trust fund. + References No definition available. + Details
Name: | ahl_MinimumTrustFund
Namespace Prefix: | ahl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 Percentage of reinsurance liabilities. + References No definition available. + Details
Name: | ahl_PercentageOfReinsuranceLiabilities
Namespace Prefix: | ahl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Regulatory deposits. + References No definition available. + Details
Name: | ahl_RegulatoryDeposits
Namespace Prefix: | ahl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Reinsurance Liabilities + References No definition available. + Details
Name: | ahl_ReinsuranceLiabilities
Namespace Prefix: | ahl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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 Restricted Cash And Collateral [Line Items] + References No definition available. + Details
Name: | ahl_RestrictedCashAndCollateralLineItems
Namespace Prefix: | ahl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 320 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=75027294&loc=d3e22002-158495 + Details
Name: | us-gaap_AssetsHeldByInsuranceRegulators
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(b)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_AssetsHeldInTrust
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_CashCashEquivalentsAndShortTermInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
Name: | us-gaap_DepreciationAndAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line. + References No definition available. + Details
Name: | us-gaap_LeaseAndRentalExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of minimum net capital required to be maintained to engage in securities transactions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Rule 15c3-1 -Number 240 -Section 15c3-1 + Details
Name: | us-gaap_MinimumNetCapitalRequired1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=ahl_UsMultiBeneficiaryTrustFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=ahl_UsSurplusLinesTrustFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=ahl_CanadianTrustFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=ahl_AustralianTrustFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=ahl_SwissTrustFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=ahl_SingaporeTrustFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ahl_BermudaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_RealEstateFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |