Investments - Other Than Temporary Impairment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Credit impairments	$ 3	$ 1	$ 2
Impairments on equity securities and other impairments	3	1	8
Total impairments	3	1	8
Cumulative Credit Impairments
Beginning balance	(19)	(25)	(110)
Additions for credit impairments recognized on:
Securities not previously impaired	(3)	0	(1)
Securities previously impaired	0	(1)	(1)
Reductions for credit impairments previously recognized on:
Securities that matured or were sold during the period	3	7	76
Securities due to an increase in expected cash flows	0	0	11
Ending balance	$ (19)	$ (19)	(25)
Equity securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Impairments on equity securities and other impairments			$ 6