Investments (EITF info-Number of securities and unrealized losses) (Details) $ in Millions	Sep. 30, 2020 USD ($) item	Dec. 31, 2019 USD ($) item
Number of Securities
Less than 12 months | item	132	78
12 months or more | item	26	53
Total | item	158	131
Unrealized Losses
Less than 12 months | $	$ (39)	$ (3)
12 months or more | $	(8)	(11)
Total | $	$ (47)	$ (14)
investment grade AFS securities with gross unrealized losses	56.00%
Corporate debt securities [Member]
Number of Securities
Less than 12 months | item	69	15
12 months or more | item	2	7
Total | item	71	22
Unrealized Losses
Less than 12 months | $	$ (29)	$ 0
12 months or more | $	(4)	(2)
Total | $	$ (33)	$ (2)
Residential mortgage backed securities [Member]
Number of Securities
Less than 12 months | item	21	29
12 months or more | item	6	20
Total | item	27	49
Unrealized Losses
Less than 12 months | $	$ (2)	$ (1)
12 months or more | $	0	(3)
Total | $	$ (2)	$ (4)
Commercial mortgage backed securities [Member]
Number of Securities
Less than 12 months | item	23	18
12 months or more | item	6	7
Total | item	29	25
Unrealized Losses
Less than 12 months | $	$ (5)	$ (1)
12 months or more | $	(2)	(2)
Total | $	$ (7)	$ (3)
State and municipal obligations [Member]
Number of Securities
Less than 12 months | item	4	5
12 months or more | item	1	3
Total | item	5	8
Unrealized Losses
Less than 12 months | $	$ (1)	$ 0
12 months or more | $	0	(2)
Total | $	$ (1)	$ (2)
Asset backed securities [Member]
Number of Securities
Less than 12 months | item	9	10
12 months or more | item	2	6
Total | item	11	16
Unrealized Losses
Less than 12 months | $	$ (1)	$ (1)
12 months or more | $	(1)	0
Total | $	$ (2)	$ (1)
Foreign government bonds and obligations [Member]
Number of Securities
Less than 12 months | item	6	1
12 months or more | item	9	10
Total | item	15	11
Unrealized Losses
Less than 12 months | $	$ (1)	$ 0
12 months or more | $	(1)	(2)
Total | $	$ (2)	$ (2)