INCOME TAXES - Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	35.00%	35.00%	35.00%
Tax computed at statutory rate of 35%	$ 24,718	$ 9,491	$ 2,815
Effect of state income taxes, net of federal benefit	2,635	1,287	1,348
Change in state income tax rates	(361)	(1,899)	1,544
Gain on acquisition	0	0	(2,643)
Non-taxable interest income	(828)	(437)	(79)
Non-taxable bank-owned life insurance	(655)	(549)	(348)
Non-deductible merger costs	94	1,006	309
Write-off of acquired net operating losses subject to Section 382 limitation	0	652	0
Change in deferred tax asset valuation allowance	(126)	(4,797)	(460)
Other	518	659	(472)
Income tax expense	$ 25,995	$ 5,413	$ 2,014