Summary of Significant Accounting Policies (New Accounting Pronouncements) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 4,235	$ 13,014	$ 14,352	$ 11,601
Other Comprehensive Income (Loss), Net of Tax	(9,247)	(1,717)	2,222
Accounting Standards Update 2018-12 | Cumulative Effect, Period of Adoption, Adjusted Balance | Minimum [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			1,000
Other Comprehensive Income (Loss), Net of Tax	2,900	3,200	5,100
Accounting Standards Update 2018-12 | Cumulative Effect, Period of Adoption, Adjusted Balance | Minimum [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	600	500
Accounting Standards Update 2018-12 | Cumulative Effect, Period of Adoption, Adjusted Balance | Maximum [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			1,300
Other Comprehensive Income (Loss), Net of Tax	4,900	5,200	$ 7,100
Accounting Standards Update 2018-12 | Cumulative Effect, Period of Adoption, Adjusted Balance | Maximum [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 900	$ 800