Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Millions, except Share data	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total Shareholders' Equity Of MBIA Inc. [Member]	Preferred Stock Of Subsidiary And Noncontrolling Interest [Member]	Total
Beginning Balance at Dec. 31, 2010	$ 275	$ 3,064	$ 2,124	$ (406)	$ (2,225)	$ 2,832	$ 14	$ 2,832
Beginning Balance (in shares) at Dec. 31, 2010	274,719,578				(74,973,978)		1,426
Comprehensive income (loss):
Net income (loss)			(693)			(693)		(693)
Other comprehensive income (loss):
Change in unrealized gains and losses on investments net of tax of $117				257		257
Portion of other-than-temporary impairment losses recognized in other comprehensive loss, net of tax of $15				29		29
Change in fair value of derivative instruments net of tax of $3				5		5
Change in foreign currency translation net of tax of $0				(33)		(33)
Other comprehensive income (loss)						258
Total comprehensive income (loss)						(435)
Share-based compensation, net of tax of $4 (in shares)	193,684				(240,401)
Share-based compensation, net of tax of $4		6			(1)	5
Treasury shares acquired under share repurchase program (in shares)					(6,541,076)
Treasury shares acquired under share repurchase program					(50)	(50)
Preferred shares of subsidiary acquired (in shares)							(111)
Preferred shares of subsidiary acquired							(2)
Change in noncontrolling interest in subsidiary							11
Significant Accounting Policies [Abstract]
Change in unrealized gains and losses and other-than-temporary impairments on investments arising during the period, net of taxes								321
Reclassification adjustment, net of taxes								(35)
Change in net unrealized gains and losses, net of taxes								286
Ending Balance at Sep. 30, 2011	$ 275	$ 3,070	$ 1,431	$ (148)	$ (2,276)	$ 2,352	$ 23	$ 2,352
Ending Balance (in shares) at Sep. 30, 2011	274,913,262				(81,755,455)		1,315