Accumulated Other Comprehensive Income (Details Of The Reclassification From AOCI) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net gains (losses) on financial instruments at fair value and foreign exchange	$ (9)	$ 17
Income (loss) before income taxes	(96)	(120)
Provision (benefit) for income taxes	2	(48)
Net income (loss)	(98)	(72)
Amounts reclassified from AOCI [Member]
Net income (loss)	0	0
Unrealized gains (losses) on AFS, net [Member] | Amounts reclassified from AOCI [Member]
Net gains (losses) on financial instruments at fair value and foreign exchange	1	2
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)	(1)	(2)
Net investment income	0	0
Income (loss) before income taxes	0	0
Provision (benefit) for income taxes	$ 0	$ 0