LONG-TERM DEBT - Net Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Disclosure [Abstract]
Interest expense	$ 21,650	$ 21,505	$ 42,617	$ 45,059
Amortization of deferred financing costs	1,197	998	2,238	1,943
Amortization of original issue discount (premium) of senior notes	(242)	(849)	(1,090)	(1,698)
Interest income and other investment income	(52)	(12)	(52)	(41)
Total net interest expense	$ 22,553	$ 21,642	$ 43,713	$ 45,263