FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measure at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Assets
Derivatives	$ 18,555	$ 11,399
Investment securities available-for-sale	1,069,667	840,468
Liabilities
Derivatives	18,836	11,916
Fair Value, Measurements, Recurring
Assets
Derivatives	18,855	11,399
Investment securities available-for-sale	1,069,667	840,468
Total	1,088,522	851,867
Liabilities
Derivatives	18,920	13,662
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 1
Assets
Derivatives	0	0
Investment securities available-for-sale	8,595	8,406
Total	8,595	8,406
Liabilities
Derivatives	0	0
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 2
Assets
Derivatives	18,855	11,399
Investment securities available-for-sale	1,061,072	832,062
Total	1,079,927	843,461
Liabilities
Derivatives	18,920	13,662
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 3
Assets
Derivatives	0	0
Investment securities available-for-sale	0	0
Total	0	0
Liabilities
Derivatives	$ 0	$ 0