Investments - Other investments by type (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Other	$ 3,786	$ 3,852
Bank loans
Schedule of Investments [Line Items]
Other	1,300	1,350
Policy loans
Schedule of Investments [Line Items]
Other	885	891
Real estate
Schedule of Investments [Line Items]
Other	776	791
Agent loans
Schedule of Investments [Line Items]
Other	639	620
Derivatives and other
Schedule of Investments [Line Items]
Other	$ 186	$ 200