Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 414	$ 633	$ 1,361	$ 1,130
Insurance loss recoverable	3,212	3,046
Deferred income taxes, net	1,400
Total assets	22,295	26,873
Liabilities:
Total liabilities	19,770	25,150
Commitments and contingencies (See Note 13)
Equity:
Preferred stock, par value $1 per share; authorized shares-10,000,000; issued and outstanding-none
Common stock, par value $1 per share; authorized shares-400,000,000; issued shares-275,479,642 and 274,896,162	275	275
Additional paid-in capital	3,071	3,072
Retained earnings	1,396	805
Accumulated other comprehensive loss, net of deferred tax of $9 and $105)	36	(176)
Treasury stock, at cost-81,732,274 and 81,752,966 shares	(2,275)	(2,276)
Total shareholders' equity of MBIA Inc.	2,503	1,700
Preferred stock of subsidiary and noncontrolling interest	22	23
Total equity	2,525	1,723
Total liabilities and equity	22,295	26,873
Non Variable Interest Entities [Member]
Assets
Fixed-maturity securities held as available-for-sale, at fair value (amortized cost $4,724 and $6,259)	4,912	6,177
Fixed-maturity securities at fair value	227	295
Investments pledged as collateral, at fair value (amortized cost $397 and $642)	308	543
Short-term investments held as available-for-sale, at fair value (amortized cost $1,591 and $1,577)	1,596	1,571
Other investments (includes investments at fair value of $50 and $96)	61	107
Total investments	7,104	8,693
Cash and cash equivalents	269	473
Premiums receivable	1,262	1,360
Deferred acquisition costs	324	351
Insurance loss recoverable	3,212	3,046
Property and equipment, at cost (less accumulated depreciation of $142 and $139)	70	69
Deferred income taxes, net	1,396	1,745
Other assets	254	243
Total assets	22,295		31,668
Liabilities:
Unearned premium revenue	3,208	3,515
Loss and loss adjustment expense reserves	835	836
Investment agreements	1,171	1,578
Medium-term notes (includes financial instruments carried at fair value $151 and $165)	1,566	1,656
Securities sold under agreements to repurchase		287
Long-term debt	1,837	1,840
Derivative liabilities	3,329	5,164
Other liabilities	407	391
Variable Interest Entity [Member]
Assets
Cash	145	160
Investments held-to-maturity, at amortized cost (fair value $2,896 and $3,489)	3,051	3,843
Fixed-maturity securities held as available-for-sale, at fair value (amortized cost $4,724 and $6,259)	537	432
Fixed-maturity securities at fair value	1,733	2,884
Loans receivable at fair value	1,903	2,046
Loan repurchase commitments	1,032	1,077
Derivative assets	1	450
Other assets	2	1
Total assets	8,400	10,900
Liabilities:
Variable interest entity notes (includes financial instruments carried at fair value $3,638 and $4,754)	7,227	8,697
Long-term debt		360
Derivative liabilities	186	825
Other liabilities	4	1
Total liabilities	$ 7,400	$ 9,900