Investments, Available-for-sale Securities in Gross Unrealized Loss Position (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Gross Unrealized Losses [Abstract]
Additional impairment losses	$ 0
Fixed Maturity Securities [Member]
Estimated Fair Value [Abstract]
Less than 12 months	1,666	$ 2,148
12 months or longer	64	272
Total	1,730	2,420
Gross Unrealized Losses [Abstract]
Less than 12 months	74	31
12 months or longer	3	14
Total	77	45
Corporate and Other Bonds [Member]
Estimated Fair Value [Abstract]
Less than 12 months	609	914
12 months or longer	12	186
Total	621	1,100
Gross Unrealized Losses [Abstract]
Less than 12 months	21	21
12 months or longer	1	11
Total	22	32
States, Municipalities and Political Subdivisions [Member]
Estimated Fair Value [Abstract]
Less than 12 months	33	34
Total	33	34
Total Asset-Backed [Member]
Estimated Fair Value [Abstract]
Less than 12 months	948	1,079
12 months or longer	52	83
Total	1,000	1,162
Gross Unrealized Losses [Abstract]
Less than 12 months	50	7
12 months or longer	2	3
Total	52	10
Residential Mortgage-Backed [Member]
Estimated Fair Value [Abstract]
Less than 12 months	71	249
12 months or longer	11	30
Total	82	279
Gross Unrealized Losses [Abstract]
Less than 12 months	1	1
Total	1	1
Commercial Mortgage-Backed [Member]
Estimated Fair Value [Abstract]
Less than 12 months	533	381
12 months or longer	28	20
Total	561	401
Gross Unrealized Losses [Abstract]
Less than 12 months	40	3
12 months or longer	2	2
Total	42	5
Other Asset-Backed [Member]
Estimated Fair Value [Abstract]
Less than 12 months	344	449
12 months or longer	13	33
Total	357	482
Gross Unrealized Losses [Abstract]
Less than 12 months	9	3
12 months or longer		1
Total	9	4
U.S. Treasury and Obligations of Government-sponsored Enterprises [Member]
Estimated Fair Value [Abstract]
Less than 12 months	63	62
12 months or longer		2
Total	63	64
Gross Unrealized Losses [Abstract]
Less than 12 months	3	2
Total	3	2
Foreign Government [Member]
Estimated Fair Value [Abstract]
Less than 12 months	13	59
12 months or longer		1
Total	$ 13	60
Gross Unrealized Losses [Abstract]
Less than 12 months		1
Total		$ 1