Accumulated Other Comprehensive Income (Details Of The Reclassification From AOCI) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net gains (losses) on financial instruments at fair value and foreign exchange	$ (17)	$ (24)	$ 84
Income (loss) before income taxes	(296)	(661)	(339)
Provision (benefit) for income taxes	0	944	(1)
Net income (loss)	(296)	(1,605)	(338)
Amounts reclassified from AOCI [Member]
Net income (loss)	0	(8)	(1)
Unrealized gains (losses) on AFS, net [Member] | Amounts reclassified from AOCI [Member]
Net gains (losses) on financial instruments at fair value and foreign exchange	6	3	7
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss)	(5)	(7)	(4)
Net investment income	(1)	(5)	(6)
Income (loss) before income taxes	0	(9)	(3)
Provision (benefit) for income taxes	$ 0	$ (1)	$ (2)