Other Comprehensive Income (Accumulated Other Comprehensive Income (Loss) Components) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity, Beginning Balance	[1]	$ 54,041	$ 49,343	$ 47,770
Other comprehensive income, net of tax		(2,361)	1,971	1,524
Total Equity, Ending Balance	[1]	55,726	54,041	49,343	$ 47,770
Continuing Operations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income, net of tax		(2,361)	1,856	1,520
Discontinued Operations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income, net of tax			115	4
Debt securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity, Beginning Balance		2,462	1,067	(80)
Cumulative effect of adopting ASU 2018-02					1,147
Other comprehensive income, net of tax		(1,873)	1,395
Total Equity, Ending Balance		589	2,462	1,067	(80)
Cash flow hedge derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity, Beginning Balance		659	276	47
Cumulative effect of adopting ASU 2018-02					229
Other comprehensive income, net of tax		(860)	383
Total Equity, Ending Balance		(201)	659	276	47
Pension and other postretirement benefit plan adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity, Beginning Balance		(345)	(408)	(530)
Cumulative effect of adopting ASU 2018-02					122
Other comprehensive income, net of tax		372	63
Total Equity, Ending Balance		27	(345)	(408)	(530)
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity, Beginning Balance		(6)	(21)	(43)
Cumulative effect of adopting ASU 2018-02					22
Other comprehensive income, net of tax			15
Total Equity, Ending Balance		(6)	(6)	(21)	(43)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity, Beginning Balance	[1]	2,770	799	(725)
Cumulative effect of adopting ASU 2018-02					1,524
Other comprehensive income, net of tax		(2,361)	1,971	1,524
Total Equity, Ending Balance	[1]	409	2,770	799	(725)
Accumulated Other Comprehensive Income (Loss) | Continuing Operations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity, Beginning Balance		2,770	914	(606)
Cumulative effect of adopting ASU 2018-02					1,520
Other comprehensive income, net of tax		(2,361)	1,856
Total Equity, Ending Balance		409	2,770	914	(606)
Accumulated Other Comprehensive Income (Loss) | Discontinued Operations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Equity, Beginning Balance			(115)	(119)
Cumulative effect of adopting ASU 2018-02					4
Other comprehensive income, net of tax			115
Total Equity, Ending Balance				$ (115)	$ (119)

[1] The par value of our preferred stock outstanding was less than $0.5 million at each date and, therefore, is excluded from this presentation.