SECURITIES - Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Total	$ 397,096	$ 372,498
Held for Investment, Fair Value, Total	397,357	369,881
Available for Sale, Amortized Cost, Total	1,018,297
Available for Sale, Fair Value, Total	1,016,744	950,503
Collateralized Loan Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Due in less than one year	0
Held for Investment, Fair Value, Due in less than one year	0
Available for Sale Amortized Cost, Due in less than one year	10,076
Available for Sale, Fair Value, Due in less than one year	10,318
Held for Investment, Amortized Cost, Due after one year through five years	3,600
Held for Investment, Fair Value, Due after one year through five years	3,600
Available for Sale, Amortized Cost, Due after one year through five years	85,126
Available for Sale, Fair Value, Due after one year through five years	85,641
Held for Investment, Amortized Cost, Due after five years through ten years	50,725
Held for Investment, Fair Value, Due after five years through ten years	51,103
Available for Sale, Amortized Cost, Due after five years through ten years	233,030
Available for Sale, Fair Value, Due after five years through ten years	234,071
Held for Investment, Amortized Cost, Due after ten years	0
Held for Investment, Fair Value, Due after ten years	0
Available for Sale, Amortized Cost, Due after ten years	28,636
Available for Sale, Fair Value, Due after ten years	28,605
Held for Investment, Amortized Cost, Total	54,325
Held for Investment, Fair Value, Total	54,703
Available for Sale, Amortized Cost, Total	356,868
Available for Sale, Fair Value, Total	358,635
Mortgage-backed securities of U.S. Government Sponsored Entities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Total	183,877
Held for Investment, Fair Value, Total	184,331	159,402
Available for Sale, Amortized Cost, Total	291,482
Available for Sale, Fair Value, Total	290,100	283,488
Collateralized Mortgage Obligations Of US Government Sponsored Entities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Total	135,596
Held for Investment, Fair Value, Total	134,493	144,964
Available for Sale, Amortized Cost, Total	217,634
Available for Sale, Fair Value, Total	214,297	234,054
Commercial mortgage backed securities of U.S. Government Sponsored Entities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Total	17,420
Held for Investment, Fair Value, Total	18,005	17,534
Available for Sale, Amortized Cost, Total	22,304
Available for Sale, Fair Value, Total	22,801	22,545
Private mortgage backed securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Total	0
Held for Investment, Fair Value, Total	0
Available for Sale, Amortized Cost, Total	32,860
Available for Sale, Fair Value, Total	33,632	31,989
Private collateralized mortgage obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Total	5,878
Held for Investment, Fair Value, Total	5,825	6,318
Available for Sale, Amortized Cost, Total	55,828
Available for Sale, Fair Value, Total	55,956	67,289
Other debt securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Total	0
Held for Investment, Fair Value, Total	0
Available for Sale, Amortized Cost, Total	10,541
Available for Sale, Fair Value, Total	71,438	73,861
Private commercial mortgage backed securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held for Investment, Amortized Cost, Total	0
Held for Investment, Fair Value, Total	0
Available for Sale, Amortized Cost, Total	30,780
Available for Sale, Fair Value, Total	$ 30,774	$ 37,172