SHARE-BASED COMPENSATION - Share-based Compensation Expense (Details) - General and Administrative Expense - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	$ 8,611	$ 3,295	$ 11,859	$ 6,959
Restricted share expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	194	336	454	1,087
Stock option expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	3,259	999	4,127	2,070
LTIP expense(1)
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	4,117	995	5,300	2,203
Performance-based LTI expense(2)
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	1,027	923	1,942	1,487
Deferred share unit (“DSU”) expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total Share-based compensation expense	$ 14	$ 42	$ 36	$ 112