Investments Investments - Debt Service and Fixed Charge Coverage Ratios (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	$ 211.5	$ 163.6
Commercial mortgage loans	147.5	97.1
Delinquent amount of loans at end of period	64.0	65.8
Commercial mortgage loans \| Nonperforming loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	0.0	0.7
Commercial mortgage loans \| Less than 50 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	0.0	14.9
Commercial mortgage loans \| 50 to 60 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	131.2	39.3
Commercial mortgage loans \| 61 to 70 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	80.3	99.5
Commercial mortgage loans \| 71 to 80 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	0.0	9.9
Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	65.4	112.1
Middle market loans \| Less than 50 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	11.0	59.8
Middle market loans \| 50 to 60 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	9.2	11.0
Middle market loans \| 61 to 70 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	15.8	6.4
Middle market loans \| 71 to 80 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	5.6	0.0
Middle market loans \| 80 to 100 Percent
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	12.0	17.2
Greater than 1.20x \| Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	66.3	82.2
Greater than 1.20x \| Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	25.8	73.6
1.00 - 1.20x \| Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	62.4	14.9
1.00 - 1.20x \| Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	22.8	0.0
Less than 1.00x \| Commercial mortgage loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	18.8	0.0
Less than 1.00x \| Middle market loans
Loans and Leases Receivable Disclosure [Line Items]
Fair market value, trading	$ 16.8	$ 38.5

CML less non-performing or future construction

No definition available.

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Namespace Prefix:	ahl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

This is the principal amount of loans (across all types of loans) that are overdue in payment by a set number of days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (e)(4)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

+ Details

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- 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

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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