Reserves for Future Policy Benefits and Contract Owner Account Balances - Contract Owner Account Balances (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Liability for Future Policy Benefit, by Product Segment [Line Items]
Contract owner account balances	$ 40,923	$ 41,183
Universal life-type contracts
Liability for Future Policy Benefit, by Product Segment [Line Items]
Contract owner account balances	5,300	5,563
Fixed annuities and payout contracts without life contingencies
Liability for Future Policy Benefit, by Product Segment [Line Items]
Contract owner account balances	34,746	34,962
Funding agreements and other
Liability for Future Policy Benefit, by Product Segment [Line Items]
Contract owner account balances	$ 877	$ 658