COMMITMENTS AND CONTINGENCIES Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet financial instruments	$ 2,443,478	$ 2,227,955
Standby letters of credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet financial instruments	15,534	18,190
Deferred standby letter of credit fees [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet financial instruments	$ 102	$ 108