Common and Preferred Stock (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Aug. 05, 2013	May 06, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2008
Class of Stock [Line Items]
Fair value of warrants			$ 33	$ 18
Treasury stock shares acquired			16,600,000	39,900,000	3,300,000
Treasury stock value acquired cost method			$ 105	$ 303	$ 35
Shares repurchased under share repurchase program, average price per share			$ 6.37	$ 7.6	$ 10.45
Remaining amount available under repurchase program			$ 88	$ 94	$ 188
Preferred stock shares issued			0	0
Preferred stock shares outstanding			0	0
Preferred Stock Par Or Stated Value Per Share			$ 1	$ 1
Blue Ridge [Member]
Class of Stock [Line Items]
Warrants outstanding		9,940,000
Warrant exercise price		$ 9.59
Preferred Stock [Member] | MBIA Insurance Corporation [Member]
Class of Stock [Line Items]
Shares repurchased under share repurchase program, average price per share			$ 10,900
Preferred stock shares issued			2,759
Preferred stock repurchased during period shares			1,444
Preferred stock, carrying value issued and outstanding			$ 28
Face value of repurchased preferred stock			10.90%
Preferred Stock Par Or Stated Value Per Share			$ 1,000
Preferred stock liquidation preference			$ 100,000
Dividend rate on preferred stock determined rate			LIBOR plus 200 basis points
2007 Repurchase Authorization [Member]
Class of Stock [Line Items]
Authorized repurchase of common stock, value			$ 1,000
2014 Repurchase Authorization [Member]
Class of Stock [Line Items]
Authorized repurchase of common stock, value			200
Remaining amount available under repurchase program			61
2016 Repurchase Authorization [Member]
Class of Stock [Line Items]
Authorized repurchase of common stock, value			100
Remaining amount available under repurchase program			$ 88
Unaffiliated Investors [Member] | MBIA Insurance Corporation [Member]
Class of Stock [Line Items]
Preferred stock shares outstanding			1,315
July 29, 2015 Repurchase Authorization [Member]
Class of Stock [Line Items]
Authorized repurchase of common stock, value			$ 100
October 28, 2015 Repurchase Authorization [Member]
Class of Stock [Line Items]
Authorized repurchase of common stock, value			$ 100
Long-Term Incentive Plan [Member]
Class of Stock [Line Items]
Treasury stock shares acquired			419,806	580,692
Warrant [Member] | Blue Ridge [Member]
Class of Stock [Line Items]
Warrant Term		5 years
Warrant [Member] | Warburg Pincus [Member]
Class of Stock [Line Items]
Warrants outstanding	11,800,000					11,500,000
Warrant exercise price	$ 29.44					$ 30.25
B Warrants [Member] | Warburg Pincus [Member]
Class of Stock [Line Items]
Warrants outstanding	10,100,000					9,800,000
Warrant exercise price	$ 29.44					$ 30.25
B2 Warrants [Member] | Warburg Pincus [Member]
Class of Stock [Line Items]
Warrants outstanding	4,004,945					4,000,000
Warrant exercise price	$ 16.18					$ 16.2
Grossup Warrant [Member] | Warburg Pincus [Member]
Class of Stock [Line Items]
Warrants outstanding	1,910,000
Warrant exercise price	$ 9.59
Warrant Term	5 years