Investments (Pledged Assets) (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2016	Dec. 31, 2015
Revolving Credit Facility [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Maximum borrowing capacity	$ 200.0
Term of credit facility	5 years
Additional commitments subject to lender approval	$ 150.0
Compliance With Reinsurance Contract Provisions Or Insurance Laws [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Restricted cash and investments	2,873.4	$ 2,748.9
Pledged As Collateral For Letter Of Credit Facilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Restricted cash and investments	$ 587.1	$ 579.3

An additional amount of commitments that may be added to the aggregate balance with approval of the lenders.

No definition available.

Name:	awh_LetterOfCreditOptionalIncrease
Namespace Prefix:	awh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

No definition available.

+ Details

Name:	us-gaap_RestrictedCashAndInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAxis=awh_ComplianceWithReinsuranceContractProvisionsOrInsuranceLawsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAxis=awh_PledgedAsCollateralForLetterOfCreditFacilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: