Accumulated Other Comprehensive Income (Details Of The Reclassification From AOCI) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 22	$ (61)	$ 13	$ (44)
Income (loss) before income taxes	(146)	(210)	(242)	(330)
Provision (benefit) for income taxes	0	1,019	2	971
Net income (loss)	(146)	(1,229)	(244)	(1,301)
Amounts reclassified from AOCI [Member]
Net income (loss)	0	4	0	4
Unrealized gains (losses) on AFS, net [Member] | Amounts reclassified from AOCI [Member]
Net gains (losses) on financial instruments at fair value and foreign exchange	0	4	1	6
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)	0	0	(1)	(2)
Net investment income	0	(1)	0	(1)
Income (loss) before income taxes	0	3	0	3
Provision (benefit) for income taxes	$ 0	$ (1)	$ 0	$ (1)