Fair Value of Assets and Liabilities - Change in unrealized gains and losses included in net income for level 3 assets and liabilities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Gains (losses) included in net income for Level 3 assets and liabilities:
Recurring Level 3 assets	$ 9	$ 13	$ 13	$ 15
Gains (losses) for Level 3 liabilities still held at the balance sheet date, included in earnings	(12)	1	(40)	24
Derivatives embedded in life and annuity contracts
Gains (losses) included in net income for Level 3 assets and liabilities:
Gains (losses) for Level 3 liabilities still held at the balance sheet date, included in earnings	(12)	1	(40)	24
Equity securities
Gains (losses) included in net income for Level 3 assets and liabilities:
Recurring Level 3 assets	10	13	14	15
Free-standing derivatives, net
Gains (losses) included in net income for Level 3 assets and liabilities:
Recurring Level 3 assets	$ (1)	$ 0	$ (1)	$ 0