Name:	bwinb_CollateralHeldThatIsEqualToUltimateLossesThatWouldBePaidOrDueInEventOfInsuredSDefault
Namespace Prefix:	bwinb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Amount of assets held either as collateral or by third parties that, upon the occurrence of any triggering event or condition under the guarantee, the guarantor can obtain and liquidate to recover all or a portion of the amounts paid under the guarantee.

No definition available.

Name:	bwinb_GuarantorObligationsCollateralHeldDirectlyOrByThirdParties
Namespace Prefix:	bwinb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The estimated amount recoverable as of the balance sheet date due from first individual reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported, and policy benefits, net of any related valuation allowance.

No definition available.

Name:	bwinb_ReinsuranceRecoverablesDueFromFirstIndividualReinsurerEstimated
Namespace Prefix:	bwinb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The estimated amount recoverable as of the balance sheet date due from second reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported, and policy benefits, net of any related valuation allowance.

No definition available.

Name:	bwinb_ReinsuranceRecoverablesDueFromSecondIndividualReinsurerEstimated
Namespace Prefix:	bwinb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The percentage of uncollateralized exposure to shareholder's equity related to a major customer.

No definition available.

Name:	bwinb_UncollateralizedExposureAsPercentageOfShareholderSEquity
Namespace Prefix:	bwinb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.