NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES - The weighted average assumptions used in the model for valuing option grants (Details 1) - Stock Options - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Nature Of Business And Significant Accounting Policies [Line Items]    
Dividend yield 0.00% 0.00%
Expected volatility 25.00% 25.00%
Risk-free interest rate 1.52% 1.68%
Expected average life 7 years 7 years
Weighted average per share fair value of options $ 11.04 $ 8.11