FAIR VALUE MEASUREMENTS - Schedule of fair values (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Temporary Equity
Noncontrolling interests subject to put provisions	$ 110,405	$ 126,483
Recurring basis
Assets
Interest rate derivative agreements asset	9	143
Liabilities
Total Liabilities	3,188	4,508
Temporary Equity
Noncontrolling interests subject to put provisions	110,405	126,483
Recurring basis | Level 1
Assets
Interest rate derivative agreements asset	0	0
Liabilities
Total Liabilities	0	0
Temporary Equity
Noncontrolling interests subject to put provisions	0	0
Recurring basis | Level 2
Assets
Interest rate derivative agreements asset	9	143
Liabilities
Total Liabilities	2,668	1,508
Temporary Equity
Noncontrolling interests subject to put provisions	0	0
Recurring basis | Level 3
Assets
Interest rate derivative agreements asset	0	0
Liabilities
Total Liabilities	520	3,000
Temporary Equity
Noncontrolling interests subject to put provisions	110,405	126,483
Prepaid expenses and other current assets | Recurring basis
Assets
Interest rate derivative agreements asset	9	143
Prepaid expenses and other current assets | Recurring basis | Level 1
Assets
Interest rate derivative agreements asset	0	0
Prepaid expenses and other current assets | Recurring basis | Level 2
Assets
Interest rate derivative agreements asset	9	143
Prepaid expenses and other current assets | Recurring basis | Level 3
Assets
Interest rate derivative agreements asset	0	0
Income tax receivable agreement payable
Liabilities
Tax receivable agreement liability	520
Income tax receivable agreement payable | Recurring basis
Liabilities
Tax receivable agreement liability	520	3,000
Income tax receivable agreement payable | Recurring basis | Level 1
Liabilities
Tax receivable agreement liability	0	0
Income tax receivable agreement payable | Recurring basis | Level 2
Liabilities
Tax receivable agreement liability	0	0
Income tax receivable agreement payable | Recurring basis | Level 3
Liabilities
Tax receivable agreement liability	520	3,000
Accrued expense and other current liabilities | Recurring basis
Liabilities
Interest rate swap agreement	2,036	783
Accrued expense and other current liabilities | Recurring basis | Level 1
Liabilities
Interest rate swap agreement	0	0
Accrued expense and other current liabilities | Recurring basis | Level 2
Liabilities
Interest rate swap agreement	2,036	783
Accrued expense and other current liabilities | Recurring basis | Level 3
Liabilities
Interest rate swap agreement	0	0
Other noncurrent liabilities | Recurring basis
Liabilities
Interest rate swap agreement	632	725
Other noncurrent liabilities | Recurring basis | Level 1
Liabilities
Interest rate swap agreement	0	0
Other noncurrent liabilities | Recurring basis | Level 2
Liabilities
Interest rate swap agreement	632	725
Other noncurrent liabilities | Recurring basis | Level 3
Liabilities
Interest rate swap agreement	$ 0	$ 0