CHANGES IN ACCOUNTING POLICIES - Narrative (Details) - Retained earnings/(deficit) $ in Millions	Jan. 01, 2020 CAD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Additional deficit on Statements of Financial Position	$ 66
ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Additional deficit on Statements of Financial Position	$ 66

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

No definition available.

Name:	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant