Insurance Premiums (Roll Forward Of Premiums Receivable) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017
Insurance Premiums [Abstract]
Premiums Receivable, Beginning balance		$ 369
Premium Payments Received		(74)		$ (50)
Premiums from New Business Written		0		3
Adjustments, Changes in Expected Term of Policies		2		(15)
Adjustments, Accretion of Premiums Receivable Discount	[1]	9		10
Adjustments, Other		(10)	[2]	12	[3]
Premiums Receivable, Ending balance		$ 296		$ 369

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

[2] Primarily consists of realized foreign exchange losses on policies denoted in CLF which is an inflationary currency.

[3] Primarily consists of premiums receivable of $267 million reported within "Assets held for sale" on MBIA's consolidated balance sheet.