Investments (Securities in a gross unrealized loss position by ratings) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	$ 29,944	$ 6,065
Gross Unrealized Losses	4,583	112
U.S. Government, Government agencies and Government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	2,360	898
Gross Unrealized Losses	360	8
AAA
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	1,566	368
Gross Unrealized Losses	318	6
AA
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	4,430	875
Gross Unrealized Losses	917	17
A
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	6,548	1,516
Gross Unrealized Losses	838	23
BBB
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	13,394	1,812
Gross Unrealized Losses	1,902	42
Non-investment grade
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	1,646	596
Gross Unrealized Losses	$ 248	$ 16