STOCK-BASED COMPENSATION - Additional Information (Details) - USD ($) $ in Millions |
12 Months Ended | ||||
---|---|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
Shares issued during the period (in shares) | 72,760,969 | 72,932,222 | |||
Time Lapse Restricted Shares | |||||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||
Vesting increment, starting with the second anniversary, over six years | 20.00% | ||||
Award vesting period | 6 years | ||||
Shares issued during the period (in shares) | 0 | 0 | 700,000 | ||
Common stock reserved for issuance upon exercise of stock options (in shares) | 4,300,000 | ||||
Unrecognized compensation cost | $ 32.9 | $ 29.9 | |||
Unrecognized compensation cost, period for recognition | 3 years 10 months 24 days | 3 years 9 months 18 days |