ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Changes in AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax
Beginning balance	$ 1,301,648	$ 1,057,448	$ 975,730
Other comprehensive income (loss)	4,941	(2,669)	2,546
Ending balance	1,655,845	1,301,648	1,057,448
Unrealized Gains (Losses) on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax
Beginning balance	927	693
Other comprehensive income (loss) before reclassifications, net of taxes	737	218
Realized (gains)/losses reclassified from accumulated other comprehensive income	(54)	16
Other comprehensive income (loss)	683	234
Ending balance	1,610	927	693
Unrealized Gains (Losses) on Derivatives Designated as Hedging Instruments
AOCI Attributable to Parent, Net of Tax
Beginning balance	(1,978)
Other comprehensive income (loss) before reclassifications, net of taxes	5,027
Realized (gains)/losses reclassified from accumulated other comprehensive income	(2,072)
Other comprehensive income (loss)	2,955
Ending balance	977	(1,978)
Unrealized Gains (Losses) on Derivatives Designated as Hedging Instruments
AOCI Attributable to Parent, Net of Tax
Beginning balance	(1,978)	925
Other comprehensive income (loss) before reclassifications, net of taxes		(7,690)
Realized (gains)/losses reclassified from accumulated other comprehensive income		4,787
Other comprehensive income (loss)		(2,903)
Ending balance		(1,978)	925
Total
AOCI Attributable to Parent, Net of Tax
Beginning balance	(1,051)	1,618	(928)
Other comprehensive income (loss) before reclassifications, net of taxes	5,764	(7,472)
Realized (gains)/losses reclassified from accumulated other comprehensive income	(2,126)	4,803
Other comprehensive income (loss)	3,638	(2,669)
Ending balance	$ 2,587	$ (1,051)	$ 1,618