Investments in Unconsolidated Funds - Selected Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Balance Sheet
Total assets	$ 9,271,377		$ 9,271,377		$ 9,349,301
Total liabilities	5,227,038		5,227,038		4,978,367
Total equity	2,480,977		2,480,977		2,712,072
Statement of Operations
Total revenues	207,796	$ 230,534	459,146	$ 454,720
Operating income	30,011	70,631	94,229	134,108
Net income	2,030	$ 33,966	28,953	62,667
Unconsolidated Funds
Balance Sheet
Total assets	134,245		134,245		136,479
Total liabilities	113,592		113,592		113,330
Total equity	$ 20,653		20,653		$ 23,149
Statement of Operations
Total revenues			7,597	41,174
Operating income			1,686	11,961
Net income			$ 372	$ 3,815