FAIR VALUE - Fair Value Measurements for Items Measured at Fair Value (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	[1]		$ 100
Loans held for sale		$ 24,306	15,332
Other real estate owned		7,640	9,949
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	[1]	955,804	950,503
Loans held for sale	[2]	24,306	15,332
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	[1]	6,600
Loans held for sale	[2]	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	[1]	949,204	950,403
Loans held for sale	[2]	24,306	15,332
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	[1]	0	0
Loans held for sale	[2]	0	0
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	[3]	4,192	4,120
Other real estate owned	[4]	7,640	9,949
Fair Value, Measurements, Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	[3]	0	0
Other real estate owned	[4]	0	0
Fair Value, Measurements, Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	[3]	3,454	3,170
Other real estate owned	[4]	60	0
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	[3]	738	950
Other real estate owned	[4]	$ 7,580	$ 9,949

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

[2] Recurring fair value basis determined using observable market data.

[3] See Note E. Nonrecurring fair value adjustments to loans identified as impaired reflect full or partial write- downs that are based on the loan’s observable market price or current appraised value of the collateral in accordance with ASC 310.

[4] Fair value is measured on a nonrecurring basis in accordance with ASC 360.