Consolidation - Revenue and Expenses of Consolidated Investment Product (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income:
Total revenues	$ 146,084	$ 145,955	$ 140,489	$ 130,718	$ 138,065	$ 152,210	$ 132,932	$ 129,028
Expenses:
Net Income (Loss) Attributable to Common Stockholders	$ 20,808	$ 22,000	$ 24,842	$ 19,662	$ 77	$ 24,913	$ 20,986	$ 21,216	$ 87,312	$ 67,192	$ 28,676
CLOs
Income:
Realized and unrealized gain (loss), net									(8,914)
Interest Income									113,053
Total revenues									104,139
Expenses:
Other operating expenses									3,367
Interest expense									92,005
Total Expense									95,372
Noncontrolling interests									1,028
Net Income (Loss) Attributable to Common Stockholders									$ 9,795