Investments (EITF info-Fair value) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value [Line Items]
Less than 12 months	$ 1,700	$ 1,079
12 months or more	115	593
Total	1,815	1,672
Corporate debt securities [Member]
Fair Value [Line Items]
Less than 12 months	789	64
12 months or more	12	90
Total	801	154
Residential mortgage backed securities [Member]
Fair Value [Line Items]
Less than 12 months	304	571
12 months or more	10	298
Total	314	869
Commercial mortgage backed securities [Member]
Fair Value [Line Items]
Less than 12 months	428	310
12 months or more	43	82
Total	471	392
State and municipal obligations [Member]
Fair Value [Line Items]
Less than 12 months	14	23
12 months or more	4	54
Total	18	77
Asset backed securities [Member]
Fair Value [Line Items]
Less than 12 months	139	111
12 months or more	36	54
Total	175	165
Foreign government bonds and obligations [Member]
Fair Value [Line Items]
Less than 12 months	26	0
12 months or more	10	15
Total	$ 36	$ 15