Common and Preferred Stock (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2020	Dec. 31, 2021
Class of Stock [Line Items]
Preferred stock shares issued	0		0
Preferred stock shares outstanding	0		0
Preferred stock par or stated value per share	$ 1		$ 1
Treasury stock shares acquired		26,400,000
Treasury stock acquired cost		$ 198
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