Common and Preferred Stock (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Shares repurchased under share repurchase program, average price per share	$ 0	$ 7.50	$ 9.12
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0
Preferred stock par or stated value per share	$ 1	$ 1
MBIA Insurance Corporation [Member]
Class of Stock [Line Items]
Preferred stock par or stated value per share	1,000
Preferred stock liquidation preference	100,000
Preferred Stock [Member] | MBIA Insurance Corporation [Member]
Class of Stock [Line Items]
Shares repurchased under share repurchase program, average price per share	$ 10,900
Preferred stock shares issued	2,759
Preferred stock repurchased during period shares	1,444
Preferred stock, carrying value issued and outstanding	$ 28
Face value of repurchased preferred stock	10.90%
Dividend rate on preferred stock determined rate	LIBOR plus 200 basis points
Unaffiliated Investors [Member] | MBIA Insurance Corporation [Member]
Class of Stock [Line Items]
Preferred stock shares outstanding	1,315