Insurance Premiums (Roll Forward Of Premiums Receivable) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020
Insurance Premiums [Abstract]
Premiums Receivable, Beginning balance		$ 216		$ 249
Premium Payments Received		(44)		(30)
Premiums from New Business Written		0		0
Adjustments, Changes in Expected Term of Policies		7		(1)
Adjustments, Accretion of Premiums Receivable Discount	[1]	5		6
Adjustments, Other		(6)	[2]	(8)	[3]
Premiums Receivable, Ending balance		$ 178		$ 216

[1] Recorded within premiums earned on MBIA’s consolidated statement of operations.

[2] The change primarily relates to a foreign exchange loss due to the termination of an international public finance credit.

[3] The change primarily relates to a reduction in installment premiums due to refunding activity and the recording of an allowance for credit losses under Financial Instruments-Credit Losses, partially offset by changes in foreign exchange currency rates.