Reinsurance (Reinsurance on premiums - long-duration contracts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effects of Reinsurance [Line Items]
Net premiums	$ 1,426	$ 1,394	$ 1,491
Traditional Long-Duration Products [Member]
Effects of Reinsurance [Line Items]
Direct premiums	621	637	642
Reinsurance ceded	(225)	(227)	(225)
Net premiums	$ 396	$ 410	$ 417