SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Anti-dilution (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Anti-dilutive common shares not included for computation of earnings per share
Basic weighted-average shares of common stock outstanding	16,138	16,131	16,022
Stock options (in shares)	72	96	120
Diluted weighted-average shares of common stock outstanding	16,210	16,227	16,142
Anti-dilutive potential shares excluded from the computation of diluted weighted average shares outstanding (in shares)	7	5	2
Stock options
Anti-dilutive common shares not included for computation of earnings per share
Anti-dilutive potential shares excluded from the computation of diluted weighted average shares outstanding (in shares)	7	5	2