LOANS - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) industry_concentration loan	Dec. 31, 2015 USD ($) loan	Dec. 31, 2014 USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of industry segment concentration above threshold limit | industry_concentration	1
Concentration risk of the loan portfolio (more than)	10.00%
Loans exposure in oil and gas industry	$ 237,400
Exposure in the oil and gas industry specified as percentage of total loans	18.50%
Loans on nonaccrual status	$ 62,580	$ 50,051
Loans with exposure in commercial real estate	559,400
Interest lost on nonaccrual loans	3,400	2,000	$ 594
Interest received on nonaccrual loans	$ 168	$ 47	$ 105
Number of loans with a pre-modification balance identified as a TDR | loan	1	1
Pre-modification balance	$ 5,500	$ 21,400
Number of defaults on loans modified as TDRs | loan	1	1
TDR defaulted on modified terms, total	$ 5,500	$ 20,300
Real estate – commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans on nonaccrual status	$ 28,688	$ 19,907
Percentage of loans on nonaccrual status	5.10%
Percentage of CRE loans secured by owner occupied commercial properties	48.00%
Oil and gas industry
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans on nonaccrual status	$ 31,900
Percentage of loans on nonaccrual status	13.40%