Investments (excluding Consolidated Investment Entities) - Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 2,862	$ 2,735	$ 2,681
Less: Investment expenses	70	66	40
Net investment income	2,792	2,669	2,641
Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	2,241	2,181	2,138
Investments in fixed maturities that did not produce net investment income	1	5
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	11	12	8
Mortgage loans on real estate
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	334	335	333
Policy loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	42	47	48
Short-term investments and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	12	14	10
Other
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 222	$ 146	$ 144