FAIR VALUE - Summary of Carrying Value and Fair Value of Company's Financial Instruments (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity		$ 392,138	$ 203,525
Loans, net		2,746,654	2,137,202
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	[1]	0	0
Loans, net		0	0
Deposit liabilities		0	0
Borrowings	[2]		0
Subordinated debt		0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	[1]	397,264	202,813
Loans, net		0	0
Deposit liabilities		0	0
Borrowings	[2]		51,788
Subordinated debt		52,785	52,785
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	[1]	0	0
Loans, net		2,743,652	2,147,024
Deposit liabilities		3,512,632	2,843,800
Borrowings	[2]		0
Subordinated debt		0	0
Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	[1]	392,138	203,525
Loans, net		2,741,950	2,129,691
Deposit liabilities		3,510,493	2,844,387
Borrowings	[2]		50,000
Subordinated debt		$ 70,171	$ 69,961

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

[2] Redemption in April 2016 and no longer outstanding