CAPITAL STOCK - PSU Outstanding (Details) - PSUs	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Awards outstanding (in shares) \| shares	1,103,311	892,077
Weighted average fair value per award outstanding (in dollars per share) \| $	$ 14.14	$ 13.41

The number of other equity instruments (ie other than share options) outstanding in a share-based payment arrangement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 2
-IssueDate 2017-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_NumberOfOtherEquityInstrumentsOutstandingInSharebasedPaymentArrangement
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant