Investments (EITF info-Number of securities and unrealized losses) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) item		Dec. 31, 2019 USD ($) item
Number of Securities
Less than 12 months | item	384		78
12 months or more | item	22		53
Total | item	406		131
Unrealized Losses
Less than 12 months	$ (490)		$ (3)
12 months or more	(14)		(11)
Total	(504)	[1]	$ (14)
Allowance for credit loss	$ 13
Corporate debt securities [Member]
Number of Securities
Less than 12 months | item	183		15
12 months or more | item	3		7
Total | item	186		22
Unrealized Losses
Less than 12 months	$ (332)		$ 0
12 months or more	(9)		(2)
Total	$ (341)	[1]	$ (2)
Residential mortgage backed securities [Member]
Number of Securities
Less than 12 months | item	88		29
12 months or more | item	7		20
Total | item	95		49
Unrealized Losses
Less than 12 months	$ (24)		$ (1)
12 months or more	(1)		(3)
Total	$ (25)		$ (4)
Commercial mortgage backed securities [Member]
Number of Securities
Less than 12 months | item	62		18
12 months or more | item	1		7
Total | item	63		25
Unrealized Losses
Less than 12 months	$ (34)		$ (1)
12 months or more	0		(2)
Total	$ (34)		$ (3)
State and municipal obligations [Member]
Number of Securities
Less than 12 months | item	5		5
12 months or more | item	1		3
Total | item	6		8
Unrealized Losses
Less than 12 months	$ (4)		$ 0
12 months or more	(1)		(2)
Total	$ (5)		$ (2)
Asset backed securities [Member]
Number of Securities
Less than 12 months | item	28		10
12 months or more | item	2		6
Total | item	30		16
Unrealized Losses
Less than 12 months	$ (90)		$ (1)
12 months or more	(1)		0
Total	$ (91)		$ (1)
Foreign government bonds and obligations [Member]
Number of Securities
Less than 12 months | item	18		1
12 months or more | item	8		10
Total | item	26		11
Unrealized Losses
Less than 12 months	$ (6)		$ 0
12 months or more	(2)		(2)
Total	$ (8)		$ (2)

[1] Unrealized losses of $13 million due to credit-related factors is recorded in the allowance for credit losses as of March 31, 2020.