Asset Management Fees - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Asset Management Fees [Member]
Disaggregation of Revenue [Line Items]
Management fee, interest and principal proceeds after incentive management fee threshold, percent	20.00%
Performance fees, net profits in excess of high water mark and credit for management fees, percent	30.00%
Asset Management Fees [Member] | Minimum [Member]
Disaggregation of Revenue [Line Items]
Management fee, net asset value of respective funds, percent	0.70%
Management Fee, Cash Received by Investors in Excess of Benchmarks, Percent	0.35%
Performance fee, net profit in excess of high water mark of respective fund, percent	10.00%
Performance fee, cash received by investors in excess of benchmarks, percent	18.00%
Asset Management Fees [Member] | Maximum [Member]
Disaggregation of Revenue [Line Items]
Management fee, net asset value of respective funds, percent	2.00%
Management Fee, Cash Received by Investors in Excess of Benchmarks, Percent	0.50%
Performance fee, net profit in excess of high water mark of respective fund, percent	20.00%
Performance fee, cash received by investors in excess of benchmarks, percent	30.00%
Asset Management and Performance Allocation Fees [Member]
Disaggregation of Revenue [Line Items]
Management and performance fees receivable	$ 9
Unearned revenues	$ 0