Investments - Unrealized loss and Limited partnerships (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Other details of unrealized loss
Limited partnership interests	$ 8,078	$ 7,505
EMA limited partnerships
Other details of unrealized loss
Limited partnership interests	6,260	5,730
Limited partnership interests
Other details of unrealized loss
Limited partnership interests	$ 1,810	$ 1,780