Investments (EITF info-Fair value) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Fair Value [Line Items]
Less than 12 months	$ 1,768	$ 1,079
12 months or more	61	593
Total	1,829	1,672
Corporate debt securities [Member]
Fair Value [Line Items]
Less than 12 months	387	64
12 months or more	15	90
Total	402	154
Residential mortgage backed securities [Member]
Fair Value [Line Items]
Less than 12 months	331	571
12 months or more	8	298
Total	339	869
Commercial mortgage backed securities [Member]
Fair Value [Line Items]
Less than 12 months	384	310
12 months or more	0	82
Total	384	392
State and municipal obligations [Member]
Fair Value [Line Items]
Less than 12 months	54	23
12 months or more	4	54
Total	58	77
Asset backed securities [Member]
Fair Value [Line Items]
Less than 12 months	595	111
12 months or more	24	54
Total	619	165
Foreign government bonds and obligations [Member]
Fair Value [Line Items]
Less than 12 months	17	0
12 months or more	10	15
Total	$ 27	$ 15