Goodwill, Deferred Leasing Costs and Other Intangibles - Goodwill and Impairment of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) multiple	Mar. 31, 2019 USD ($)
Goodwill [Line Items]
Goodwill impairment	$ 79,000	$ 0
Discount rate for carried interest (percent)	20.00%
Minimum
Goodwill [Line Items]
Terminal year residual multiples on fee related earnings | multiple	16
Terminal year residual discount rate (percentage)	10.00%
Maximum
Goodwill [Line Items]
Terminal year residual multiples on fee related earnings | multiple	20
Terminal year residual discount rate (percentage)	15.00%
Other investment management
Goodwill [Line Items]
Goodwill transferred between reporting units	$ (51,000)
Goodwill impairment	79,000
Digital
Goodwill [Line Items]
Goodwill transferred between reporting units	$ 51,000