ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 2,757,596	$ 2,437,150	$ 2,647,088	$ 2,469,582
Reclassification for gains included in net income, net of tax	0	0	0	0
Current year changes, net of tax	(1,066)	62	(8,481)	21,618
Balance at end of period	2,837,004	2,460,130	2,837,004	2,460,130
Unrealized Gain (Loss) on Derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	0	(244)	0	(147)
Reclassification for gains included in net income, net of tax	0	0	0	0
Current year changes, net of tax	0	111	0	14
Balance at end of period	0	(133)	0	(133)
Unrealized Gain (Loss) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	26,090	39,795	33,505	18,142
Reclassification for gains included in net income, net of tax	0	0	0	0
Current year changes, net of tax	(1,066)	(49)	(8,481)	21,604
Balance at end of period	25,024	39,746	25,024	39,746
Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	26,090	39,551	33,505	17,995
Balance at end of period	$ 25,024	$ 39,613	$ 25,024	$ 39,613