Accumulated Other Comprehensive Income Loss - AOCI Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 17,843
Other comprehensive income (loss), net of tax	$ (1,563)	$ 306	(3,434)	$ (600)
Ending balance	14,226	18,244	14,226	18,244
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(266)	1,909	1,616	2,834
OCI before reclassifications	(2,080)	426	(4,549)	(740)
Amounts reclassified from AOCI	65	(53)	152	(57)
OCI, before tax	(2,015)	373	(4,397)	(797)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	423	(78)	923	167
Other comprehensive income (loss), net of tax	(1,592)	295	(3,474)	(630)
Ending balance	(1,858)	2,204	(1,858)	2,204
AOCI, Gain (Loss), Debt Securities, Available-for-sale, with Allowance for Credit Loss, Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(2)	(2)	(2)	(2)
OCI before reclassifications	0	0	0	0
Amounts reclassified from AOCI	0	0	0	0
OCI, before tax	0	0	0	0
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	0	0	0	0
Other comprehensive income (loss), net of tax	0	0	0	0
Ending balance	(2)	(2)	(2)	(2)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	5	17	6	12
OCI before reclassifications	38	2	45	17
Amounts reclassified from AOCI	(6)	(8)	(14)	(17)
OCI, before tax	32	(6)	31	0
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(7)	1	(7)	0
Other comprehensive income (loss), net of tax	25	(5)	24	0
Ending balance	30	12	30	12
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	41	44	41	43
OCI before reclassifications	(10)	2	(10)	4
Amounts reclassified from AOCI	0	0	0	0
OCI, before tax	(10)	2	(10)	4
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	2	0	2	(1)
Other comprehensive income (loss), net of tax	(8)	2	(8)	3
Ending balance	33	46	33	46
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,477)	(1,704)	(1,489)	(1,717)
OCI before reclassifications	(1)	(1)	(1)	(2)
Amounts reclassified from AOCI	16	19	31	36
OCI, before tax	15	18	30	34
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(3)	(4)	(6)	(7)
Other comprehensive income (loss), net of tax	12	14	24	27
Ending balance	(1,465)	(1,690)	(1,465)	(1,690)
AOCI Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,699)	264	172	1,170
OCI before reclassifications	(2,053)	429	(4,515)	(721)
Amounts reclassified from AOCI	75	(42)	169	(38)
OCI, before tax	(1,978)	387	(4,346)	(759)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	415	(81)	912	159
Other comprehensive income (loss), net of tax	(1,563)	306	(3,434)	(600)
Ending balance	$ (3,262)	$ 570	$ (3,262)	$ 570