DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING ACTIVITIES - AOCI (Details) - USD ($) $ in Thousands	3 Months Ended					9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 966,260	$ 617,275	$ 624,440	$ 624,485	$ 626,705	$ 617,275	$ 626,705
Other comprehensive income before reclassifications	0		214			0	1,973
Amounts reclassified from accumulated other comprehensive income (loss)	0		(397)			(1,806)	(566)
Net current period other comprehensive income	0	(1,806)	(183)	407	1,183	(1,806)	1,407
Ending balance	360,601	909,507	623,438	624,440	624,485	360,601	623,438
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0	$ 1,806	3,221		$ 1,631	1,806	1,631
Ending balance	$ 0		$ 3,038	$ 3,221		$ 0	$ 3,038