Accumulated Other Comprehensive Income (Details Of The Reclassification From AOCI) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net gains (losses) on financial instruments at fair value and foreign exchange	$ (26)	$ 22	$ (4)	$ 13
Income (loss) before income taxes	(207)	(146)	(226)	(242)
Net income (loss)	(170)	(146)	(187)	(244)
Amounts reclassified from AOCI [Member]
Net income (loss)	(44)	0	(37)	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	(16)	0	23	1
Net investment losses related to OTTI	(9)	0	(37)	(1)
Income (loss) before income taxes	(25)	0	(14)	0
Instrument-specific credit risk of liabilities measured at fair value, net [Member] | Amounts reclassified from AOCI [Member]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ (19)	$ 0	$ (23)	$ 0