Schedule II (Condensed Balance Sheets) (Detail) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets [Abstract]
Cash and cash equivalents	$ 146	$ 187	$ 522	$ 782
Total assets	9,095	11,137	14,836
Liabilities:
Long-term debt	2,121	1,986
Total liabilities	7,670	7,898
Equity:
Preferred stock, par value $1 per share; authorized shares--10,000,000; issued and outstanding--none	0	0
Common stock, par value $1 per share; authorized shares--400,000,000; issued shares-- 283,717,973 and 283,989,999	284	284
Additional paid-in capital	3,171	3,160
Retained earnings	1,095	2,700
Accumulated other comprehensive income (loss), net of tax	(19)	(128)	(61)	21
Treasury stock, at cost-- 192,233,526 and 148,789,168 shares	(3,118)	(2,789)
Total shareholders' equity of MBIA Inc.	1,413	3,227
Total liabilities and equity	9,095	11,137
Fixed-maturity securities held as available-for-sale, amortized cost	$ 4,438	$ 5,450
Preferred stock, par value	$ 1	$ 1
Preferred stock, authorized shares	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	283,717,973	283,989,999
Treasury stock, shares	192,233,526	148,789,168
Parent Company [Member]
Assets [Abstract]
Fixed-maturity securities held as available-for-sale, at fair value (amortized cost $590 and $687)	$ 639	$ 725
Investments carried at fair value	8	6
Investments pledged as collateral, at fair value (amortized cost $155 and $242)	148	233
Short-term investments held as available-for-sale, at fair value (amortized cost $283 and $278)	283	278
Other investments	1	2
Total investments	1,079	1,244
Cash and cash equivalents	10	13	$ 35	$ 100
Investment in wholly-owned subsidiaries	2,290	3,673
Deferred income taxes, net	0	1,003
Other assets	144	107
Total assets	3,523	6,040
Liabilities:
Investment agreements	301	361
Long-term debt	576	576
Affiliate loans payable	772	901
Income taxes payable	237	696
Other liabilities	224	279
Total liabilities	2,110	2,813
Equity:
Preferred stock, par value $1 per share; authorized shares--10,000,000; issued and outstanding--none	0	0
Common stock, par value $1 per share; authorized shares--400,000,000; issued shares-- 283,717,973 and 283,989,999	284	284
Additional paid-in capital	3,171	3,160
Retained earnings	1,095	2,700
Accumulated other comprehensive income (loss), net of tax	(19)	(128)
Treasury stock, at cost-- 192,233,526 and 148,789,168 shares	(3,118)	(2,789)
Total shareholders' equity of MBIA Inc.	1,413	3,227
Total liabilities and equity	3,523	6,040
Fixed-maturity securities held as available-for-sale, amortized cost	590	687
Investments pledged as collateral, amortized cost	155	242
Short-term investments held as available-for-sale, amortized cost	$ 283	$ 278
Preferred stock, par value	$ 1	$ 1
Preferred stock, authorized shares	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	283,717,973	283,989,999
Treasury stock, shares	192,233,526	148,789,168