Investments (excluding Consolidated Investment Entities) - Loans by U.S. Region (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Open Option Contracts Written [Line Items]
Recorded investment	$ 6,879	$ 7,283
Percentage of Total	100.00%	100.00%
Pacific
Open Option Contracts Written [Line Items]
Recorded investment	$ 1,627	$ 1,699
Percentage of Total	23.60%	23.30%
South Atlantic
Open Option Contracts Written [Line Items]
Recorded investment	$ 1,462	$ 1,519
Percentage of Total	21.30%	20.90%
Middle Atlantic
Open Option Contracts Written [Line Items]
Recorded investment	$ 1,326	$ 1,351
Percentage of Total	19.30%	18.60%
West South Central
Open Option Contracts Written [Line Items]
Recorded investment	$ 719	$ 817
Percentage of Total	10.50%	11.20%
Mountain
Open Option Contracts Written [Line Items]
Recorded investment	$ 670	$ 706
Percentage of Total	9.70%	9.70%
East North Central
Open Option Contracts Written [Line Items]
Recorded investment	$ 571	$ 666
Percentage of Total	8.30%	9.10%
New England
Open Option Contracts Written [Line Items]
Recorded investment	$ 117	$ 109
Percentage of Total	1.70%	1.50%
West North Central
Open Option Contracts Written [Line Items]
Recorded investment	$ 283	$ 338
Percentage of Total	4.10%	4.60%
East South Central
Open Option Contracts Written [Line Items]
Recorded investment	$ 104	$ 78
Percentage of Total	1.50%	1.10%