Investments, Investment Gains (Losses) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Investment Gains (Losses) [Abstract]
Investment gains (losses)	[1]	$ 57	$ (216)
Gross investment gains on available-for-sale securities		58	29
Gross investment losses on available-for-sale securities		20	104
Fixed Maturity Securities [Member]
Investment Gains (Losses) [Abstract]
Investment gains (losses)		38	(75)
Equity Securities [Member]
Investment Gains (Losses) [Abstract]
Investment gains (losses)		2	(133)
Derivative Instruments [Member]
Investment Gains (Losses) [Abstract]
Investment gains (losses)		17	5
Short Term Investments and Other [Member]
Investment Gains (Losses) [Abstract]
Investment gains (losses)			(13)
Nonredeemable Preferred Stock [Member]
Investment Gains (Losses) [Abstract]
Recognized gains (losses) on securities		$ 2	$ (133)

[1] Gross investment gains on available-for-sale securities were $58 and $29 for the three months ended March 31, 2021 and 2020. Gross investment losses on available-for-sale securities were $20 and $104 for the three months ended March 31, 2021 and 2020. During the three months ended March 31, 2021 and 2020, $2 of investment gains and $133 of investment losses were recognized due to the change in fair value of non-redeemable preferred stock still held as of March 31, 2021 and 2020.