Common and Preferred Stock - (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	12 Months Ended
	Dec. 07, 2023	Aug. 31, 2022	Dec. 31, 2023	May 03, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Treasury stock shares acquired			3,600,000
Preferred stock shares issued			0		0
Shares repurchased under share repurchase program, average price per share			$ 8.12
Preferred stock shares outstanding			0		0
Preferred stock par or stated value per share			$ 1		$ 1
Shares repurchased under share repurchase program remaining authorized amount			$ 71	$ 100
Excise tax percenatge		1.00%
Dividend declared per common share	$ 8
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]
Preferred stock shares issued			2,759
Preferred stock, carrying value issued and outstanding			$ 28
Preferred stock repurchased during period shares			1,444
Shares repurchased under share repurchase program, average price per share			$ 10,900
Face value of repurchased preferred stock			10.90%
Dividend rate on preferred stock determined rate			SOFR plus 2.26161%
Preferred Stock [Member] | MBIA Insurance Corporation [Member] | Secured Overnight Financing Rate ("SOFR") [Member]
Class of Stock [Line Items]
Preferred stock dividend rate			2.26161%
Unaffiliated Investors [Member] | MBIA Insurance Corporation [Member]
Class of Stock [Line Items]
Preferred stock shares outstanding			1,315