Loans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Rate On Term Loan	4.68%ambc_InterestRateOnTermLoan	4.62%ambc_InterestRateOnTermLoan
Loan Maturity Date	Jun. 30, 2026
Loans, Unpaid principal balance	$ 6,936ambc_LoansUnpaidPrincipalBalance	$ 7,734ambc_LoansUnpaidPrincipalBalance

This represents the amount of principal outstanding on loans receivable that are presented on the balance sheet at fair value, whether such presentation is as a separate caption or parenthetical disclosure.

No definition available.

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