INCOME TAXES - Difference Between Statutory and Effective Rates (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Difference between statutory federal income tax rate and effective tax rates
Statutory rate (as a percent)	34.00%	34.00%
Increase (decrease) resulting from:
State taxes, net of federal tax benefit (as a percent)	7.80%	4.70%
Bank-owned life insurance (as a percent)	5.80%	1.40%
Stock compensation plans (as a percent)	8.70%	1.50%
Interest income from municipal securities (as a percent)	(4.20%)	(0.80%)
Merger related expense, non-deductible	27.30%
Other, net (as a percent)	0.40%
Effective tax rates (as a percent)	68.20%	38.00%