SHARE-BASED COMPENSATION - Share-based Compensation Expense (Details) - General and Administrative Expense - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	$ 2,604	$ 3,310	$ 14,463	$ 10,269
Restricted share expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	199	297	653	1,384
Stock option expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	432	992	4,559	3,062
LTIP expense(1)
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	1,023	1,171	6,323	3,374
Performance-based LTI expense(2)
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	944	828	2,886	2,315
Deferred share unit (“DSU”) expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	$ 6	$ 22	$ 42	$ 134