INCOME TAXES (Details 1) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed statutory federal income tax provision									$ 39,226	$ 32,262	$ 29,310
State taxes, net of federal tax benefit									5,643	4,500	4,104
Nontaxable interest, net									(996)	(973)	(795)
New Markets Tax Credits									(6,360)	(6,514)	(6,708)
Low Income Housing Project Investments									(1,641)	(1,182)	(594)
Increase in cash surrender value of life insurance and gain on life insurance benefits									(1,431)	(1,292)	(1,782)
Merger and other related costs (non-deductible)									210	185	274
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount									28	41	0
Other, net									748	191	90
Total expense	$ 7,698	$ 9,793	$ 9,508	$ 8,428	$ 8,268	$ 7,867	$ 7,213	$ 3,869	$ 35,427	$ 27,218	$ 23,899
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Computed statutory federal income tax provision									35.00%	35.00%	35.00%
State taxes, net of federal tax benefit									5.03%	4.88%	4.90%
Nontaxable interest, net									(0.89%)	(1.06%)	(0.95%)
New Markets Tax Credits									(5.67%)	(7.07%)	(8.01%)
Low Income Housing Project Investments									(1.46%)	(1.28%)	(0.71%)
Increase in cash surrender value of life insurance and gain on life insurance benefits									(1.28%)	(1.40%)	(2.13%)
Merger and other related costs (non-deductible)									0.19%	0.20%	0.33%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent									0.02%	0.04%	0.00%
Other, net									0.67%	0.22%	0.11%
Total expense									31.61%	29.53%	28.54%