FAIR VALUE MEASUREMENTS - Financial Liabilities at Fair Value on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financial Liabilities:
Total liabilities measured at fair value on a recurring basis	$ 6,838	$ 5,900
Restricted Stock
Financial Liabilities:
Performance-based equity awards	6,754	3,789
Cash-Settled Award | Restricted Stock Units
Financial Liabilities:
Cash-settled restricted stock units	84	2,111
Level 1
Financial Liabilities:
Total liabilities measured at fair value on a recurring basis	6,838	5,900
Level 1 | Restricted Stock
Financial Liabilities:
Performance-based equity awards	6,754	3,789
Level 1 | Cash-Settled Award | Restricted Stock Units
Financial Liabilities:
Cash-settled restricted stock units	84	2,111
Level 2
Financial Liabilities:
Total liabilities measured at fair value on a recurring basis	0	0
Level 2 | Restricted Stock
Financial Liabilities:
Performance-based equity awards	0	0
Level 2 | Cash-Settled Award | Restricted Stock Units
Financial Liabilities:
Cash-settled restricted stock units	0	0
Level 3
Financial Liabilities:
Total liabilities measured at fair value on a recurring basis	0	0
Level 3 | Restricted Stock
Financial Liabilities:
Performance-based equity awards	0	0
Level 3 | Cash-Settled Award | Restricted Stock Units
Financial Liabilities:
Cash-settled restricted stock units	$ 0	$ 0