SECURITIES - Amortized Cost and Fair Value of Securities Available for Sale and Held for Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	$ 916,406	$ 960,809
Gross Unrealized Gains, Available for Sale	4,457	3,767
Gross Unrealized Losses, Available for Sale	(11,588)	(14,073)
Fair Value, Available for Sale	909,275	950,503
Gross Amortized Cost, Held for Investment Securities	379,657	372,498
Gross Unrealized Gains, Held for Investment Securities	2,083	1,753
Gross Unrealized Losses, Held for Investment Securities	(3,508)	(4,370)
Fair Value, Held for Investment Securities	378,232	369,881
U.S. Treasury Securities and obligations of U.S. Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	11,366	12,073
Gross Unrealized Gains, Available for Sale	273	255
Gross Unrealized Losses, Available for Sale	0	0
Fair Value, Available for Sale	11,639	12,328
Mortgage-backed securities of U.S. Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	290,933	287,726
Gross Unrealized Gains, Available for Sale	706	585
Gross Unrealized Losses, Available for Sale	(3,847)	(4,823)
Fair Value, Available for Sale	287,792	283,488
Gross Amortized Cost, Held for Investment Securities	188,402	159,941
Gross Unrealized Gains, Held for Investment Securities	871	704
Gross Unrealized Losses, Held for Investment Securities	(1,332)	(1,243)
Fair Value, Held for Investment Securities	187,941	159,402
Collateralized Mortgage Obligations Of US Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	228,035	238,805
Gross Unrealized Gains, Available for Sale	385	314
Gross Unrealized Losses, Available for Sale	(4,778)	(5,065)
Fair Value, Available for Sale	223,642	234,054
Gross Amortized Cost, Held for Investment Securities	140,786	147,208
Gross Unrealized Gains, Held for Investment Securities	395	386
Gross Unrealized Losses, Held for Investment Securities	(2,041)	(2,630)
Fair Value, Held for Investment Securities	139,140	144,964
Commercial mortgage backed securities of U.S. Government Sponsored Entities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	22,328	22,351
Gross Unrealized Gains, Available for Sale	369	222
Gross Unrealized Losses, Available for Sale	(21)	(28)
Fair Value, Available for Sale	22,676	22,545
Gross Amortized Cost, Held for Investment Securities	17,399	17,375
Gross Unrealized Gains, Held for Investment Securities	383	233
Gross Unrealized Losses, Held for Investment Securities	(23)	(74)
Fair Value, Held for Investment Securities	17,759	17,534
Private mortgage backed securities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	32,816	32,780
Gross Unrealized Gains, Available for Sale	0	0
Gross Unrealized Losses, Available for Sale	(651)	(791)
Fair Value, Available for Sale	32,165	31,989
Fair Value, Held for Investment Securities	6,084
Private collateralized mortgage obligations [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	61,173	67,542
Gross Unrealized Gains, Available for Sale	548	563
Gross Unrealized Losses, Available for Sale	(647)	(816)
Fair Value, Available for Sale	61,074	67,289
Gross Amortized Cost, Held for Investment Securities	6,166	6,427
Gross Unrealized Gains, Held for Investment Securities	4	0
Gross Unrealized Losses, Held for Investment Securities	(86)	(109)
Fair Value, Held for Investment Securities	6,084	6,318
Collateralized loan obligations [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	101,883	124,716
Gross Unrealized Gains, Available for Sale	917	838
Gross Unrealized Losses, Available for Sale	(71)	(665)
Fair Value, Available for Sale	102,729	124,889
Gross Amortized Cost, Held for Investment Securities	26,904	41,547
Gross Unrealized Gains, Held for Investment Securities	430	430
Gross Unrealized Losses, Held for Investment Securities	(26)	(314)
Fair Value, Held for Investment Securities	27,308	41,663
Obligations of state and political subdivisions [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	62,989	63,161
Gross Unrealized Gains, Available for Sale	709	622
Gross Unrealized Losses, Available for Sale	(860)	(895)
Fair Value, Available for Sale	62,838	62,888
Corporate and other debt securities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	72,480	74,121
Gross Unrealized Gains, Available for Sale	410	257
Gross Unrealized Losses, Available for Sale	(341)	(517)
Fair Value, Available for Sale	72,549	73,861
Fair Value, Held for Investment Securities	0
Commercial mortgage backed securities [Member]
Amortized cost and fair value of securities available for sale and held for investment
Gross Amortized Cost, Available for Sale	32,403	37,534
Gross Unrealized Gains, Available for Sale	140	111
Gross Unrealized Losses, Available for Sale	(372)	(473)
Fair Value, Available for Sale	32,171	$ 37,172
Fair Value, Held for Investment Securities	$ 0