SHARE-BASED COMPENSATION - Restricted Stock Units and Restricted Stock Awards (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Restricted Stock Units
Number of Shares Subject to Restriction
Outstanding at the beginning of the period (in shares)			1,869,029
Granted (in shares)			5,864,924
Vested and issued (in shares)			(310,936)
Cancelled/expired (in shares)			(877,119)
Outstanding at the end of the period (in shares)	6,545,898		6,545,898
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)			$ 21.67
Granted (in dollars per share)			7.55
Vested and issued (in dollars per share)			20.29
Forfeited (in dollars per share)			22.46
Outstanding at the end of the period (in dollars per share)	$ 8.94		$ 8.94
Performance-based RSUs
Additional disclosures
Share-based compensation expense	$ 1,015	$ 845	$ 1,074	$ 852
Percentage of performance-based RSUs granted shares accounted will be earned			28.60%
Total compensation cost not yet recognized	$ 3,891		$ 3,891
Weighted average period to recognize compensation cost related to non-vested options not yet recognized			1 year 3 months 10 days
Make-whole inducement award, performance-based RSUs | Key employees
Number of Shares Subject to Restriction
Granted (in shares)	172,838
Make-whole inducement award, service-based RSUs | Key employees
Number of Shares Subject to Restriction
Granted (in shares)			243,209
Sign-on inducement award, performance-based RSUs | Executive
Number of Shares Subject to Restriction
Granted (in shares)		1,498,500
Restricted Stock Awards
Number of Shares Subject to Restriction
Outstanding at the beginning of the period (in shares)			43,355
Granted (in shares)			186,969
Vested and issued (in shares)			(20,829)
Cancelled/expired (in shares)			(5,929)
Outstanding at the end of the period (in shares)	203,566		203,566
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)			$ 20.91
Granted (in dollars per share)			4.51
Vested and issued (in dollars per share)			22.20
Forfeited (in dollars per share)			21.63
Outstanding at the end of the period (in dollars per share)	$ 5.69		$ 5.69
Additional disclosures
Vesting period			1 year
Share-based compensation expense	$ 215	$ 139	$ 341	277
Total compensation cost not yet recognized	859		$ 859
Weighted average period to recognize compensation cost related to non-vested options not yet recognized			10 months 13 days
Weighted average service-based RSUs
Additional disclosures
Share-based compensation expense	2,205	$ 3,974	$ 3,798	$ 4,841
Total compensation cost not yet recognized	$ 24,807		$ 24,807
Weighted average period to recognize compensation cost related to non-vested options not yet recognized			2 years 4 months 13 days
Minimum | Restricted Stock Units
Additional disclosures
Vesting period			1 year
Minimum | Performance-based RSUs
Additional disclosures
Percentage of performance-based RSUs granted shares accounted will be earned	0.00%
Maximum | Restricted Stock Units
Additional disclosures
Vesting period			3 years
Maximum | Performance-based RSUs
Additional disclosures
Percentage of performance-based RSUs granted shares accounted will be earned	30.00%
2014 Plan | Performance-based RSUs | Key employees
Number of Shares Subject to Restriction
Granted (in shares)	1,835,000
2014 Plan | Restricted Stock Awards | Non-employee director
Number of Shares Subject to Restriction
Granted (in shares)			186,969
2014 Plan | Weighted average service-based RSUs | Key employees
Number of Shares Subject to Restriction
Granted (in shares)			2,115,377