Reinsurance (Reinsurance on premiums - long-duration contracts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Net premiums	$ 1,395	$ 2,224	$ 2,467
Traditional long-duration products [Member]
Effects of Reinsurance [Line Items]
Direct premiums	565	621	621
Reinsurance ceded	(224)	(224)	(225)
Net premiums	$ 341	$ 397	$ 396