Fresh Start Financial Statement Reporting - Schedule of Liabilities Subject to Compromise (Parenthetical) (Detail) (USD $)	6 Months Ended
Jun. 30, 2013
Reorganizations [Abstract]
Litigation settlement amount	$ 14,007

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

No definition available.

Name:	ambc_LitigationSettlementAmount
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration