Accumulated Other Comprehensive Income (Changes In The Components Of AOCI) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Beginning balance			$ 115
Other comprehensive income (loss) before reclassifications			(50)
Amounts reclassified from AOCI			25
Total other comprehensive income (loss)	$ (13)	$ 1	(25)	$ 132
Ending balance	90		90
Unrealized gains (losses) on AFS, net [Member]
Beginning balance			176
Other comprehensive income (loss) before reclassifications			(42)
Amounts reclassified from AOCI			(11)
Total other comprehensive income (loss)			(53)
Ending balance	123		123
Foreign currency translation, net [Member]
Beginning balance			(10)
Other comprehensive income (loss) before reclassifications			3
Amounts reclassified from AOCI			0
Total other comprehensive income (loss)			3
Ending balance	(7)		(7)
Instrument-specific credit risk of liabilities measured at fair value, net [Member]
Beginning balance			(51)
Other comprehensive income (loss) before reclassifications			(11)
Amounts reclassified from AOCI			36
Total other comprehensive income (loss)			25
Ending balance	$ (26)		$ (26)