CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 1,427	$ 2,512	$ 2,193
Unrealized gains (losses) on available-for-sale debt securities:
Unrealized holding gains (losses) arising during the year	1,153	1,046	(371)
Reclassification adjustment for net (gains) losses included in net income	(34)	(7)	9
Unrealized gains on cash flow hedge derivatives:
Unrealized holding gains arising during the year	483	275
Unrealized holding gains arising during the year			169
Reclassification adjustment for net (gains) losses included in net income	(187)	(13)
Reclassification adjustment for net (gains) losses included in net income			2
Defined benefit pension plans, net:
Net actuarial (loss) gain arising during the year	(9)	(5)	1
Reclassification of amounts to net periodic benefit costs	7	8	7
Other	(4)	0	0
Other comprehensive income (loss), net of tax	1,409	1,304	(183)
Comprehensive Income	$ 2,836	$ 3,816	$ 2,010