Investments - Other investments by type (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Other	$ 3,904	$ 3,852
Bank loans
Schedule of Investments [Line Items]
Other	1,223	1,350
Policy loans
Schedule of Investments [Line Items]
Other	892	891
Real estate
Schedule of Investments [Line Items]
Other	917	791
Agent loans
Schedule of Investments [Line Items]
Other	663	620
Derivatives and other
Schedule of Investments [Line Items]
Other	$ 209	$ 200