CREDIT FACILITY - Old and New Credit Facility (Details) $ in Thousands	1 Months Ended	6 Months Ended	12 Months Ended
	Jul. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
CREDIT FACILITY
Face amount of debt		$ 1,114,970	$ 838,985
Credit Facility
CREDIT FACILITY
Actual total secured leverage ratio		4.05
Secured leverage ratio threshold for contingent principle payments			3.75
Credit Facility | Maximum
CREDIT FACILITY
Actual total secured leverage ratio		6.25
First Lien Term Loan
CREDIT FACILITY
Face amount of debt		$ 803,000
Quarterly installment repayments		2,007
First Lien Revolver
CREDIT FACILITY
Face amount of debt	$ 350,000
Accordion feature		650,000
Quarterly installment repayments	$ 2,891
Debt discount (as a percent)	0.25%
Maximum borrowing capacity		$ 30,000
Unused commitment fee (as a percent)		0.50%
First Lien Revolver Step Down One
CREDIT FACILITY
Unused commitment fee (as a percent)		0.375%
First Lien Revolver Step Down Two
CREDIT FACILITY
Unused commitment fee (as a percent)		0.25%
LIBOR | First Lien Term Loan
CREDIT FACILITY
Margin (as a percent)		2.50%
LIBOR | First Lien Revolver
CREDIT FACILITY
Margin (as a percent)		2.00%
LIBOR | First Lien Revolver Step Down One
CREDIT FACILITY
Margin (as a percent)		1.75%
LIBOR | First Lien Revolver Step Down Two
CREDIT FACILITY
Margin (as a percent)		1.50%
LIBOR | First Lien Revolver Step Down Three
CREDIT FACILITY
Margin (as a percent)		1.25%
Base rate | Credit Facility
CREDIT FACILITY
Margin (as a percent)		1.50%
Base rate | First Lien Revolver
CREDIT FACILITY
Margin (as a percent)		1.00%
Base rate | First Lien Revolver Step Down One
CREDIT FACILITY
Margin (as a percent)		0.75%
Base rate | First Lien Revolver Step Down Two
CREDIT FACILITY
Margin (as a percent)		0.50%
Base rate | First Lien Revolver Step Down Three
CREDIT FACILITY
Margin (as a percent)		0.25%