EARNINGS PER SHARE - Antidilutive securities (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Options to purchase common shares, RSUs and PSUs
Potential common shares excluded from the calculation of diluted net loss per share
Number of antidilutive shares	9,128	7,334	9,128	7,334
Warrants to purchase common shares - equity classified
Potential common shares excluded from the calculation of diluted net loss per share
Number of antidilutive shares	884	3,561	884	992
2022 Notes convertible into common shares
Potential common shares excluded from the calculation of diluted net loss per share
Number of antidilutive shares	9,057	9,057	9,057	9,057