Investments - Other investments by type (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Other	$ 3,856	$ 3,852
Bank loans
Schedule of Investments [Line Items]
Other	1,259	1,350
Policy loans
Schedule of Investments [Line Items]
Other	880	891
Real estate
Schedule of Investments [Line Items]
Other	872	791
Agent loans
Schedule of Investments [Line Items]
Other	654	620
Derivatives and other
Schedule of Investments [Line Items]
Other	$ 191	$ 200