Total Equity and Other Comprehensive Income (Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax [Abstract]
Net unrealized gains (losses) on securities, pre-tax	$ 654	$ (6,318)
Less: Net realized gains (losses) reclassified to earnings	(215)	(3)
Net increase (decrease), pre-tax	869	(6,315)
Other Comprehensive Income (Loss), Available-for-sale Securities, before Reclassification Adjustments, Tax [Abstract]
Net unrealized gains (losses) on securities, tax effect	(154)	1,489
Less: Net realized gains (losses) reclassified to earnings, tax effect	51	1
Effect of income taxes	(205)	1,488
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, After Reclassification Adjustments, after Tax [Abstract]
Net unrealized gains (losses) on securities, after tax	500	(4,829)
Less: Net realized gains (losses) reclassified to earnings, after tax	(164)	(2)
Net increase (decrease), after-tax	664	(4,827)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax [Abstract]
Net unrealized gains (losses) on cash flow hedges, pre-tax	197	(1,656)
Less: Net realized gains (losses) reclassified to earnings, pre-tax	(330)	102
Net increase (decrease), pre-tax	527	(1,758)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax [Abstract]
Net unrealized gains (losses) on cash flow hedges, tax effect	(46)	390
Less: Net realized gains (losses) reclassified to earnings, tax effect	78	(24)
Effect of income taxes	(124)	414
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract]
Net unrealized gains (losses) on cash flow hedges, after tax	151	(1,266)
Less: Net realized gains (losses) reclassified to earnings, after tax	(252)	78
Net increase (decrease), after-tax	403	(1,344)
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	(10)	54
Net increase (decrease), pre-tax	(10)	54
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	2	(13)
Effect of income taxes	2	(13)
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	(8)	41
Net increase (decrease), after-tax	(8)	41
Other Comprehensive Income Other Adjustments [Abstract]
Net unrealized gains (losses) on other transactions, pre-tax	4	(3)
Net increase (decrease), pre-tax	4	(3)
Net unrealized gains (losses) on other transactions, tax effect	1	(7)
Effect of income taxes	1	(7)
Net unrealized gains (losses) on other transactions, after tax	5	(10)
Net increase (decrease), after-tax	5	(10)
Other comprehensive income (loss), before tax and net of reclassifications into Net income	1,390	(8,022)
Total other comprehensive income (loss), tax effect	(326)	1,882
Other comprehensive income (loss), after tax and net of reclassifications into Net income	$ 1,064	$ (6,140)