DERIVATIVE AND HEDGING INSTRUMENTS - Summary of Derivative Notional Amounts (Details) - Cross Currency Interest Rate Swaps [Member] - Designated as Hedging Instrument [Member] CAD in Thousands, $ in Thousands	Sep. 30, 2017 USD ($)	Sep. 30, 2017 CAD	Dec. 31, 2016 USD ($)	Dec. 31, 2016 CAD
Cash Flow Hedging [Member]
Derivative [Line Items]
Notional amount	$ 845,000	CAD 125,000	$ 245,000	CAD 125,000
Net Investment Hedging [Member]
Derivative [Line Items]
Notional amount		56,300		56,300
Derivative liability, notional amount		CAD 125,000		CAD 125,000