FAIR VALUE - Summary of Carrying Value and Fair Value of Company's Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014	Mar. 31, 2014
Securities held to maturity	$ 223,061		$ 207,904
Loans, net	1,836,766		1,804,814
Quoted Prices in Active Markets for Identical Assets Level 1 [Member]
Securities held to maturity	0	[1]	0
Loans, net	0			0
Deposit liabilities	0			0
Borrowings	0			0
Subordinated debt	0			0
Significant Other Observable Inputs Level 2 [Member]
Securities held to maturity	226,506	[1]	208,788
Loans, net	0			0
Deposit liabilities	0			0
Borrowings	52,729			53,584
Subordinated debt	53,898			53,861
Significant Unobservable Inputs Level 3 [Member]
Securities held to maturity	0	[1]	0
Loans, net	1,849,559			1,814,746
Deposit liabilities	2,610,845			2,417,355
Borrowings	0			0
Subordinated debt	0			0
Carrying Amount [Member]
Securities held to maturity	223,061	[1]	207,904
Loans, net	1,827,526			1,794,405
Deposit liabilities	2,609,825			2,416,534
Borrowings	50,000			50,000
Subordinated debt	$ 64,627			$ 64,583

[1] See Note D for further detail of fair value of individual investment categories.