DERIVATIVES AND HEDGING - Fair Value of Derivatives of Consolidated Funds (Details) - Not Designated as Hedging Instrument - Consolidated Funds - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Notional	$ 45,047
Fair Value	339
Liabilities
Notional	(27,713)
Fair Value	(546)
Foreign-currency forward contracts
Assets
Notional	44,310	$ 166,917
Fair Value	319	6,890
Liabilities
Notional	(17,045)	(140,276)
Fair Value	(375)	$ (2,551)
Total-return and interest-rate and credit default swaps
Assets
Notional	0
Fair Value	0
Liabilities
Notional	(3,783)
Fair Value	(159)
Options and futures
Assets
Notional	737
Fair Value	20
Liabilities
Notional	(6,885)
Fair Value	$ (12)