SUMMARY OF ACCOUNTING POLICIES - Accounting changes (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Significant Accounting Policies [Abstract]
Impact of adopting IFRS 15	$ (18,980)	$ 18,980	$ 0

Cumulative Effect Of New Accounting Principle In Period Of Adoption1

No definition available.

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