Investments (excluding Consolidated Investment Entities) - Loans by Property Type (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investment Holdings [Line Items]
Recorded investment	$ 6,879	$ 7,283
Percentage of Total	100.00%	100.00%
Retail
Investment Holdings [Line Items]
Recorded investment	$ 1,873	$ 2,067
Percentage of Total	27.30%	28.30%
Industrial
Investment Holdings [Line Items]
Recorded investment	$ 1,636	$ 1,803
Percentage of Total	23.80%	24.80%
Apartments
Investment Holdings [Line Items]
Recorded investment	$ 1,797	$ 1,696
Percentage of Total	26.10%	23.30%
Office
Investment Holdings [Line Items]
Recorded investment	$ 999	$ 1,144
Percentage of Total	14.50%	15.70%
Hotel/Motel
Investment Holdings [Line Items]
Recorded investment	$ 188	$ 162
Percentage of Total	2.70%	2.20%
Other
Investment Holdings [Line Items]
Recorded investment	$ 324	$ 347
Percentage of Total	4.70%	4.80%
Mixed Use
Investment Holdings [Line Items]
Recorded investment	$ 62	$ 64
Percentage of Total	0.90%	0.90%