GOODWILL AND OTHER INTANGIBLE ASSETS- Intangible assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortizing acquired intangible assets
Gross Carry Amount	$ 1,547,345	$ 1,517,725
Accumulated Amortization	(548,475)	(514,269)
Net Book Value	998,870	1,003,456
Customer relationships
Amortizing acquired intangible assets
Gross Carry Amount	1,390,984	1,362,104
Accumulated Amortization	(503,469)	(471,361)
Net Book Value	887,515	890,743
Management contracts
Amortizing acquired intangible assets
Gross Carry Amount	151,010	150,464
Accumulated Amortization	(41,785)	(39,888)
Net Book Value	109,225	110,576
Other intangibles
Amortizing acquired intangible assets
Gross Carry Amount	5,351	5,157
Accumulated Amortization	(3,221)	(3,020)
Net Book Value	$ 2,130	$ 2,137