Schedule II - Additional Information Schedule II - Additional Information (Detail) - USD ($)	1 Months Ended	8 Months Ended	12 Months Ended
	Apr. 30, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	May. 01, 2013
Condensed Financial Statements, Captions [Line Items]
Date of incorporation			Apr. 29, 1991	Apr. 29, 1991
Capital stock, shares authorized	150,000,000
Common stock, shares authorized	130,000,000
Common stock, par value	$ 0.01
Preferred stock, shares authorized	20,000,000
Preferred stock, par value	$ 0.01
Common stock, shares issued	45,000,000
Warrants issued exercise price	$ 16.67
Amount transferred to escrow account	$ 30,000,000
Junior surplus note of Ambac Assurance Segregated Account	$ 350,000,000					$ 350,000,000
Percentage of voting rights, common stock				10.00%
Common Stock Voting Restriction Less One Vote				10.00%
Holder's ownership				5.00%
Change in holder's ownership				5.00%
Voting shares of the emerging entity	50.00%
Par Value of Owner Trust Certificate				$ 74,794,000
Par Value of Private Placement				$ 299,175,000
Private Placement Par Value Proceeds				80.00%
Private Placement Maturity Date				Aug. 28, 2039
Interest Rate on Private Placement Obligations				5.10%
Ambac Financial Group, Inc Parent Company Only [Member]
Condensed Financial Statements, Captions [Line Items]
Common stock, shares authorized			130,000,000	130,000,000
Common stock, par value			$ 0.01	$ 0.01
Preferred stock, shares authorized			20,000,000	20,000,000
Preferred stock, par value			$ 0.01	$ 0.01
Common stock, shares issued			45,044,222	45,005,932
Ambac Assurance [Member]
Condensed Financial Statements, Captions [Line Items]
Reimbursement of operating expenses	$ 5,000,000
Ambac Assurance [Member] | 2017 [Member]
Condensed Financial Statements, Captions [Line Items]
Maximum Reimbursement Of Operating Expenses after 2017	$ 4,000,000
Successor [Member]
Condensed Financial Statements, Captions [Line Items]
Common stock, shares authorized			130,000,000	130,000,000
Common stock, par value			$ 0.01	$ 0.01		$ 0.01
Preferred stock, shares authorized			20,000,000	20,000,000
Preferred stock, par value			$ 0.01	$ 0.01
Common stock, shares issued			45,044,222	45,005,932		45,000,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	5,047,138					5,047,138
Warrants issued exercise price						$ 16.67
Stock Issued During Period, Shares, New Issues			236	949	2,524
Warrant exercised			740	949	6,312
Proceeds from the sale of Junior Surplus Notes of the Segregated Account		$ 0	$ 0	$ 224,262,000
Successor [Member] | Ambac Financial Group, Inc Parent Company Only [Member]
Condensed Financial Statements, Captions [Line Items]
Proceeds from the sale of Junior Surplus Notes of the Segregated Account		$ 0	$ 0	$ 224,262,000