Investments (excluding Consolidated Investment Entities) - Loans by Loan to Value Ratio and Debt Service Coverage Ratio (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule of Loans by Loan to Value Ratio [Line Items]
Benchmark loan to value ratio, greater than indicates unpaid loan amount exceeds underlying collateral	100.00%	100.00%
Benchmark debt service coverage ratio, less than indicates property's operations income is less than debt payments	100.00%	100.00%
Recorded investment	$ 6,879	$ 7,283
Percent of Total	100.00%	100.00%
Greater than 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 5,333	$ 5,654
Debt Service Coverage Ratio, minimum	150.00%	150.00%
Greater than 1.25x - 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 793	$ 689
Debt Service Coverage Ratio, minimum	125.00%	125.00%
Debt Service Coverage Ratio, maximum	150.00%	150.00%
Greater than 1.0x - 1.25x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 497	$ 797
Debt Service Coverage Ratio, minimum	100.00%	100.00%
Debt Service Coverage Ratio, maximum	125.00%	125.00%
Less than 1.0x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 256	$ 84
Debt Service Coverage Ratio, maximum	100.00%	100.00%
0% - 50%
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 687	$ 620
Percent of Total	10.00%	8.50%
Loan to Value Ratio, minimum	0.00%	0.00%
Loan to Value Ratio, maximum	50.00%	50.00%
0% - 50% | Greater than 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 650	$ 553
0% - 50% | Greater than 1.25x - 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	24	39
0% - 50% | Greater than 1.0x - 1.25x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	11	26
0% - 50% | Less than 1.0x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	2	2
Greater than 50% - 60%
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 1,723	$ 1,753
Percent of Total	25.00%	24.10%
Loan to Value Ratio, minimum	50.00%	50.00%
Loan to Value Ratio, maximum	60.00%	60.00%
Greater than 50% - 60% | Greater than 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 1,597	$ 1,653
Greater than 50% - 60% | Greater than 1.25x - 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	53	57
Greater than 50% - 60% | Greater than 1.0x - 1.25x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	36	37
Greater than 50% - 60% | Less than 1.0x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	37	6
Greater than 60% - 70%
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 3,710	$ 4,285
Percent of Total	53.90%	58.80%
Loan to Value Ratio, minimum	60.00%	60.00%
Loan to Value Ratio, maximum	70.00%	70.00%
Greater than 60% - 70% | Greater than 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 2,669	$ 3,106
Greater than 60% - 70% | Greater than 1.25x - 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	581	463
Greater than 60% - 70% | Greater than 1.0x - 1.25x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	329	631
Greater than 60% - 70% | Less than 1.0x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	131	53
Greater than 70% - 80%
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 703	$ 568
Percent of Total	10.20%	7.80%
Loan to Value Ratio, minimum	70.00%	70.00%
Loan to Value Ratio, maximum	80.00%	80.00%
Greater than 70% - 80% | Greater than 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 384	$ 324
Greater than 70% - 80% | Greater than 1.25x - 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	119	124
Greater than 70% - 80% | Greater than 1.0x - 1.25x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	121	93
Greater than 70% - 80% | Less than 1.0x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	79	23
Greater than 80% and above
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 56	$ 57
Percent of Total	0.90%	0.80%
Loan to Value Ratio, minimum	80.00%	80.00%
Greater than 80% and above | Greater than 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 33	$ 18
Greater than 80% and above | Greater than 1.25x - 1.5x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	16	6
Greater than 80% and above | Greater than 1.0x - 1.25x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	0	10
Greater than 80% and above | Less than 1.0x
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	7	0
Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	0	59
Commercial mortgage loans secured by land or construction loans | 0% - 50%
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	0	0
Commercial mortgage loans secured by land or construction loans | Greater than 50% - 60%
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	0	0
Commercial mortgage loans secured by land or construction loans | Greater than 60% - 70%
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	0	32
Commercial mortgage loans secured by land or construction loans | Greater than 70% - 80%
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	0	4
Commercial mortgage loans secured by land or construction loans | Greater than 80% and above
Schedule of Loans by Loan to Value Ratio [Line Items]
Recorded investment	$ 0	$ 23