Total Equity and Other Comprehensive Income (Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax [Abstract]
Net unrealized gains (losses) on securities, pre-tax	$ (476)	$ (2,929)	$ 178	$ (9,247)
Less: Net realized gains (losses) reclassified to earnings	(235)	(214)	(450)	(217)
Net increase (decrease), pre-tax	(241)	(2,715)	628	(9,030)
Other Comprehensive Income (Loss), Available-for-sale Securities, before Reclassification Adjustments, Tax [Abstract]
Net unrealized gains (losses) on securities, tax effect	112	690	(42)	2,179
Less: Net realized gains (losses) reclassified to earnings, tax effect	55	50	106	51
Effect of income taxes	57	640	(148)	2,128
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, After Reclassification Adjustments, after Tax [Abstract]
Net unrealized gains (losses) on securities, after tax	(364)	(2,239)	136	(7,068)
Less: Net realized gains (losses) reclassified to earnings, after tax	(180)	(164)	(344)	(166)
Net increase (decrease), after-tax	(184)	(2,075)	480	(6,902)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax [Abstract]
Net unrealized gains (losses) on cash flow hedges, pre-tax	(689)	(676)	(492)	(2,332)
Less: Net realized gains (losses) reclassified to earnings, pre-tax	(373)	25	(703)	127
Net increase (decrease), pre-tax	(316)	(701)	211	(2,459)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax [Abstract]
Net unrealized gains (losses) on cash flow hedges, tax effect	162	159	116	549
Less: Net realized gains (losses) reclassified to earnings, tax effect	88	(6)	166	(30)
Effect of income taxes	74	165	(50)	579
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract]
Net unrealized gains (losses) on cash flow hedges, after tax	(527)	(517)	(376)	(1,783)
Less: Net realized gains (losses) reclassified to earnings, after tax	(285)	19	(537)	97
Net increase (decrease), after-tax	(242)	(536)	161	(1,880)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Reclassification Adjustment, before Tax [Abstract]
Net pension and other postretirement benefit plan activity and other reclassified to earnings, pre-tax	6	8	(4)	62
Net increase (decrease), pre-tax	6	8	(4)	62
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax [Abstract]
Net pension and other postretirement benefit plan activity and other reclassified to earnings, tax effect	(1)	(2)	1	(15)
Effect of income taxes	(1)	(2)	1	(15)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract]
Net pension and other postretirement benefit plan activity and other reclassified to earnings, after-tax	5	6	(3)	47
Net increase (decrease), after-tax	5	6	(3)	47
Other Comprehensive Income Other Adjustments [Abstract]
Net unrealized gains (losses) on other transactions, pre-tax	3	(4)	7	(7)
Net increase (decrease), pre-tax	3	(4)	7	(7)
Net unrealized gains (losses) on other transactions, tax effect	1	(18)	2	(25)
Effect of income taxes	1	(18)	2	(25)
Net unrealized gains (losses) on other transactions, after tax	4	(22)	9	(32)
Net increase (decrease), after-tax	4	(22)	9	(32)
Other comprehensive income (loss), before tax and net of reclassifications into Net income	(548)	(3,412)	842	(11,434)
Total other comprehensive income (loss), tax effect	131	785	(195)	2,667
Other comprehensive income (loss), after tax and net of reclassifications into Net income	$ (417)	$ (2,627)	$ 647	$ (8,767)