XML 54 R43.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Investments - Summary of Investment Income (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Schedule of Investment Income, Reported Amounts, by Category [Line Items] |  |  |  |
Gross investment income | $ 52.7 | $ 50.2 | $ 102.6 | $ 100.8
Investment expenses | (2.3) | (2.8) | (4.9) | (5.7)
Net investment income | 50.4 | 47.4 | 97.7 | 95.1
Total fixed income securities — Available for sale |  |  |  |
Schedule of Investment Income, Reported Amounts, by Category [Line Items] |  |  |  |
Gross investment income | 33.5 | 33.9 | 66.8 | 67.8
Fixed Income Maturities - Trading |  |  |  |
Schedule of Investment Income, Reported Amounts, by Category [Line Items] |  |  |  |
Gross investment income | 13.2 | 10.4 | 25.2 | 20.5
Short-term investments |  |  |  |
Schedule of Investment Income, Reported Amounts, by Category [Line Items] |  |  |  |
Gross investment income | 0.3 | 0.2 | 0.5 | 0.3
Short-term Investment, Trading |  |  |  |
Schedule of Investment Income, Reported Amounts, by Category [Line Items] |  |  |  |
Gross investment income | 0.1 | 0.3 | 0.3 | 0.5
Fixed term deposits (included in cash and cash equivalents) |  |  |  |
Schedule of Investment Income, Reported Amounts, by Category [Line Items] |  |  |  |
Gross investment income | 4.2 | 1.3 | 6.6 | 2.0
Equity securities — Trading |  |  |  |
Schedule of Investment Income, Reported Amounts, by Category [Line Items] |  |  |  |
Gross investment income | 0.7 | 3.7 | 1.9 | 8.9
Catastrophe bonds — Trading |  |  |  |
Schedule of Investment Income, Reported Amounts, by Category [Line Items] |  |  |  |
Gross investment income | $ 0.7 | $ 0.4 | $ 1.3 | $ 0.8

X
- Definition Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.1-5) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
Name: | us-gaap_InterestAndDividendIncomeOperating
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of expenses related to the generation of investment income. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.9) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.2) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 + Details
Name: | us-gaap_InvestmentIncomeInvestmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(2)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: 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 G)) -URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574960-122915 + Details
Name: | us-gaap_NetInvestmentIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_ScheduleOfInvestmentIncomeReportedAmountsByCategoryLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

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

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

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

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

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

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