Accounting for derivative instruments and hedging activities (Tables)

6 Months Ended

Jun. 30, 2020

Accounting for derivative instruments and hedging activities

Schedule of notional volumes of forecasted transactions

		June 30,	December 31,
	Units	2020	2019
Natural gas swaps	Natural Gas (MMBtu)	14.5	16.3
Gas purchase agreements	Natural Gas (Gigajoules)	6.6	6.4
Interest rate swaps	Interest (US$)	441.4	468.4

Schedule of fair value of derivative instruments

	June 30, 2020
	Derivative		Derivative
	Assets		Liabilities
Derivative instruments designated as cash flow hedges:
Interest rate swaps current	$	—	$	0.6
Interest rate swaps long-term		—		1.3
Total derivative instruments designated as cash flow hedges		—		1.9
Derivative instruments not designated as cash flow hedges:
Interest rate swaps current		—		5.4
Interest rate swaps long-term		—		3.1
Natural gas swaps current		—		2.0
Natural gas swaps long-term		—		3.5
Gas purchase agreements current		—		4.1
Gas purchase agreements long-term		—		6.2
Convertible debenture conversion option		—		5.2
Total derivative instruments not designated as cash flow hedges		—		29.5
Total derivative instruments	$	—	$	31.4

	December 31, 2019
	Derivative		Derivative
	Assets		Liabilities
Derivative instruments designated as cash flow hedges:
Interest rate swaps current	$	—	$	0.4
Interest rate swaps long-term		—		1.1
Total derivative instruments designated as cash flow hedges		—		1.5
Derivative instruments not designated as cash flow hedges:
Interest rate swaps current				1.9
Interest rate swaps long-term		—		1.1
Natural gas swaps current		—		1.9
Natural gas swaps long-term		—		4.2
Gas purchase agreements current		0.7		4.6
Gas purchase agreements long-term		—		9.5
Convertible debenture conversion option		—		3.2
Total derivative instruments not designated as cash flow hedges		0.7		26.4
Total derivative instruments	$	0.7	$	27.9

Schedule of changes in OCI attributable to derivative financial instruments designated as cash flow hedges

	Interest Rate
Three Months Ended June 30, 2020	Swaps
Accumulated OCI balance at April 1, 2020	$	1.3
Change in fair value of cash flow hedges		(0.1)
Realized from OCI during the period		0.1
Accumulated OCI balance at June 30, 2020	$	1.3
	Interest Rate
Three Months Ended June 30, 2019	Swaps
Accumulated OCI balance at April 1, 2019	$	1.5
Change in fair value of cash flow hedges		0.1
Realized from OCI during the period		(0.2)
Accumulated OCI balance at June 30, 2019	$	1.4
	Interest Rate
Six Months Ended June 30, 2020	Swaps
Accumulated OCI balance at January 1, 2020	$	1.6
Change in fair value of cash flow hedges		(0.5)
Realized from OCI during the period		0.2
Accumulated OCI balance at June 30, 2020	$	1.3
	Interest Rate
Six Months Ended June 30, 2019	Swaps
Accumulated OCI balance at January 1, 2019	$	1.6
Change in fair value of cash flow hedges		0.1
Realized from OCI during the period		(0.3)
Accumulated OCI balance at June 30, 2019	$	1.4

Summary of realized loss (gain) for derivative instruments not designated as cash flow hedges

The following table summarizes realized loss (gain) for derivative instruments not designated as cash flow hedges:

	Classification of loss (gain)	Three Months Ended June 30,				Six Months Ended June 30,
	recognized in income	2020		2019		2020		2019
Gas purchase agreements	Fuel	$	1.9	$	2.0	$	4.1	$	4.0
Natural gas swaps	Fuel		0.9		0.2		1.6		(0.1)
Interest rate swaps	Interest, net		0.9		2.4		1.2		3.8

Summary of the unrealized gain (loss) resulting from changes in the fair value of derivative financial instruments that are not designated as cash flow hedges

	Classification of (loss) gain	Three Months Ended June 30,				Six Months Ended June 30,
	recognized in income	2020		2019		2020		2019
Natural gas swaps	Change in fair value of derivatives	$	1.1	$	(2.6)	$	0.6	$	(2.4)
Gas purchase agreements	Change in fair value of derivatives		1.4		0.2		2.4		(0.3)
Interest rate swaps	Change in fair value of derivatives		0.6		(4.6)		(5.5)		(6.7)
		$	3.1	$	(7.0)	$	(2.5)	$	(9.4)
Convertible debenture conversion option	Other (income) expense, net	$	(0.6)	$	(2.9)	$	2.0	$	1.8