Financial Guarantee Insurance Contracts Financial Guarantee Insurance Contracts - Summary of Percentage Ceded to Reinsurers and Reinsurance Recoverable and Rating Levels (Details) $ in Thousands	Jun. 30, 2015 USD ($)
Insurance [Abstract]
Loss Reserves Ceded To Reinsurers	$ 71,031

The known and estimated amount recoverable as of the balance sheet date from reinsurers for claims expected to be paid or incurred by the ceding insurer.

No definition available.

Name:	ambc_LossReservesCededToReinsurers
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant