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STOCK-BASED COMPENSATION - Stock Options - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Granted (in shares) 0 0 0
Total intrinsic value of stock options exercised $ 146,000 $ 507,000 $ 12,000,000
Compensation expense $ 0 $ 0 $ 0
Shares tendered to net share settle (in shares) 0 0 13,959
Value of shares tendered to net share settle exercise of options     $ 429,000
Fair value of shares withheld for tax withholding obligations $ 9,432,000 $ 4,871,000 $ 5,337,000
Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares withheld for tax withholding obligations (in shares)     30,186
Fair value of shares withheld for tax withholding obligations     $ 1,300,000