Investments (Equity Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt and Equity Securities, FV-NI [Line Items]
Equity Securities, FV-NI, Unrealized Gain (Loss)	$ 2,256	$ 1,980
Equity securities	1,269	1,079
Common Stock [Member]
Debt and Equity Securities, FV-NI [Line Items]
Equity Securities, FV-NI, Cost	784	644
Equity Securities, FV-NI, Unrealized Gain (Loss)	295	135
Equity securities	1,079	779
Nonredeemable Preferred Stock [Member]
Debt and Equity Securities, FV-NI [Line Items]
Equity Securities, FV-NI, Cost	189	297
Equity Securities, FV-NI, Unrealized Gain (Loss)	1	3
Equity securities	190	300
Equity securities
Debt and Equity Securities, FV-NI [Line Items]
Equity Securities, FV-NI, Cost	973	941
Equity Securities, FV-NI, Unrealized Gain (Loss)	296	138
Equity securities	$ 1,269	$ 1,079