ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 2,469,582	$ 1,456,347
Reclassification for gains included in net income, net of tax	0	(94)
Current year changes, net of tax	19,257	20,402
Ending balance	2,564,683	2,420,723
Unrealized Gain (Loss) on Derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(147)	351
Reclassification for gains included in net income, net of tax	0	0
Current year changes, net of tax	147	(471)
Ending balance	0	(120)
Unrealized Gain (Loss) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	18,142	(5,177)
Reclassification for gains included in net income, net of tax	0	(94)
Current year changes, net of tax	19,110	20,873
Ending balance	37,252	15,602
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	17,995	(4,826)
Ending balance	$ 37,252	$ 15,482