Businesses, Developments, Risks And Uncertainties (Schedule Of Error Corrections And Prior Period Adjustments, Balance Sheet) (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010	Mar. 31, 2011 MBIA [Member] Balance As Reported [Member]	Mar. 31, 2011 Balance As Reported [Member]	Mar. 31, 2011 MBIA [Member] Correction Of Error [Member]	Mar. 31, 2011 Correction Of Error [Member]	Mar. 31, 2011 MBIA [Member] Balance As Revised [Member]	Mar. 31, 2011 Balance As Revised [Member]
Deferred income taxes, net				$ 1,293		$ 70		$ 1,363
Total assets				32,173		70		32,243
Derivative liabilities			1,910	5,927	108	99	2,018	6,026
Total liabilities	29,763	29,433		30,400		207		30,607
Retained earnings	986	2,124		987		(137)		850
Total shareholders' equity of MBIA Inc.	1,881	2,832		1,759		(137)		1,622
Total equity	1,905	2,846		1,773		(137)		1,636
Total liabilities and equity	$ 31,668	$ 32,279		$ 32,173		$ 70		$ 32,243