Accumulated Other Comprehensive Income - Activity in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	$ (1,826)	$ 1,836	$ 1,696
Other comprehensive income (loss), tax effect	432	(427)	(392)
Other	0	(4)	0
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	23,111	21,203	16,250
Other comprehensive (loss) income, net of tax	(1,394)	1,409	1,304
Ending balance	22,210	23,111	21,203
Net unrealized gains on available-for-sale debt securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(1,366)	1,514	1,369
Other comprehensive income (loss), before reclassifications, tax effect	323	(361)	(323)
Other comprehensive income (loss), before reclassifications, net activity	(1,043)	1,153	1,046
Reclassification adjustment, pre-tax activity	4	(45)	(9)
Reclassification adjustment, tax effect	(1)	11	2
Reclassification adjustment, net activity	3	(34)	(7)
Other comprehensive income (loss), pre-tax activity	(1,362)	1,469	1,360
Other comprehensive income (loss), tax effect	322	(350)	(321)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	1,931	812	(227)
Other comprehensive (loss) income, net of tax	(1,040)	1,119	1,039
Ending balance	891	1,931	812
Net unrealized gains on cash flow hedge derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	(185)	611	348
Other comprehensive income (loss), before reclassifications, tax effect	43	(128)	(73)
Other comprehensive income (loss), before reclassifications, net activity	(142)	483	275
Reclassification adjustment, pre-tax activity	(293)	(237)	(16)
Reclassification adjustment, tax effect	70	50	3
Reclassification adjustment, net activity	(223)	(187)	(13)
Other comprehensive income (loss), pre-tax activity	(478)	374	332
Other comprehensive income (loss), tax effect	113	(78)	(70)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	718	422	160
Other comprehensive (loss) income, net of tax	(365)	296	262
Ending balance	353	718	422
Defined benefit pension plans, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, pre-tax activity	5	(12)	(5)
Other comprehensive income (loss), before reclassifications, tax effect	(1)	3	0
Other comprehensive income (loss), before reclassifications, net activity	4	(9)	(5)
Reclassification adjustment, pre-tax activity	9	9	9
Reclassification adjustment, tax effect	(2)	(2)	(1)
Reclassification adjustment, net activity	7	7	8
Other comprehensive income (loss), pre-tax activity	14	(3)	4
Other comprehensive income (loss), tax effect	(3)	1	(1)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(44)	(42)	(45)
Other comprehensive (loss) income, net of tax	11	(2)	3
Ending balance	(33)	(44)	(42)
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pre-tax activity	0	(4)
Other comprehensive income (loss), tax effect	0	0
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(4)	0
Other comprehensive (loss) income, net of tax	0	(4)
Ending balance	(4)	(4)	0
AOCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	2,601	1,192	(112)
Ending balance	$ 1,207	$ 2,601	$ 1,192