Business and Risks (Narrative) (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014 segments	Jun. 30, 2014 Mbia Inc [Member]	Dec. 31, 2013 Mbia Inc [Member]	Jun. 30, 2014 Mbia Inc General Corporate Purposes [Member]	Dec. 31, 2013 Mbia Inc General Corporate Purposes [Member]	Jun. 30, 2014 Asset Liability Products Segment [Member]	Dec. 31, 2013 Asset Liability Products Segment [Member]
Business Acquisition [Line Items]
Number of operating segments	3
Liquid assets		$ 365,000,000	$ 359,000,000	$ 317,000,000	$ 307,000,000	$ 48,000,000	$ 52,000,000
Amount released from tax escrow account	202,000,000
Commuted gross insured exposure	$ 3,900,000,000