FAIR VALUE MEASUREMENTS - Fair Value Hierarchy (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Liabilities / Other Current Liabilities:
Total	$ (49,735)	$ (14,168)
Money market funds
Cash equivalents:
Cash equivalents	42,063	41,933
Level 1
Liabilities / Other Current Liabilities:
Total	42,063	41,933
Level 1 | Money market funds
Cash equivalents:
Cash equivalents	42,063	41,933
Level 2
Liabilities / Other Current Liabilities:
Total	(74,899)	(39,311)
Level 2 | Money market funds
Cash equivalents:
Cash equivalents	0	0
Level 3
Liabilities / Other Current Liabilities:
Total	(16,899)	(16,790)
Level 3 | Money market funds
Cash equivalents:
Cash equivalents	0	0
Other Current Liabilities | Contingent consideration
Liabilities / Other Current Liabilities:
Contingent consideration	(3,828)	(3,719)
Other Current Liabilities | Interest rate swaps
Liabilities / Other Current Liabilities:
Interest rate swaps	(16,949)	(8,354)
Other Current Liabilities | Level 1 | Contingent consideration
Liabilities / Other Current Liabilities:
Contingent consideration	0	0
Other Current Liabilities | Level 1 | Interest rate swaps
Liabilities / Other Current Liabilities:
Interest rate swaps	0	0
Other Current Liabilities | Level 2 | Contingent consideration
Liabilities / Other Current Liabilities:
Contingent consideration	0	0
Other Current Liabilities | Level 2 | Interest rate swaps
Liabilities / Other Current Liabilities:
Interest rate swaps	(16,949)	(8,354)
Other Current Liabilities | Level 3 | Contingent consideration
Liabilities / Other Current Liabilities:
Contingent consideration	(3,828)	(3,719)
Other Current Liabilities | Level 3 | Interest rate swaps
Liabilities / Other Current Liabilities:
Interest rate swaps	0	0
Other Liabilities | Contingent consideration
Liabilities / Other Current Liabilities:
Contingent consideration	(13,071)	(13,071)
Other Liabilities | Interest rate swaps
Liabilities / Other Current Liabilities:
Interest rate swaps	(57,950)	(30,957)
Other Liabilities | Level 1 | Contingent consideration
Liabilities / Other Current Liabilities:
Contingent consideration	0	0
Other Liabilities | Level 1 | Interest rate swaps
Liabilities / Other Current Liabilities:
Interest rate swaps	0	0
Other Liabilities | Level 2 | Contingent consideration
Liabilities / Other Current Liabilities:
Contingent consideration	0	0
Other Liabilities | Level 2 | Interest rate swaps
Liabilities / Other Current Liabilities:
Interest rate swaps	(57,950)	(30,957)
Other Liabilities | Level 3 | Contingent consideration
Liabilities / Other Current Liabilities:
Contingent consideration	(13,071)	(13,071)
Other Liabilities | Level 3 | Interest rate swaps
Liabilities / Other Current Liabilities:
Interest rate swaps	$ 0	$ 0