v3.20.2

Accounting for derivative instruments and hedging activities (Tables) | 6 Months Ended
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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

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- Definition Tabular disclosure for realized gains and losses on derivative instruments not designated as hedging instruments of (a) the location and amount of gains and losses reported in the statement of financial performance and (b) the location and fair value amounts of the instruments reported in the statement of financial position. + References No definition available. + Details
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- Definition Tabular disclosure for unrealized gains and losses on derivative instruments not designated as hedging instruments of (a) the location and amount of gains and losses reported in the statement of financial performance and (b) the location and fair value amounts of the instruments reported in the statement of financial position. + References No definition available. + Details
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- Definition Tabular disclosure of gain (loss) on derivative and nonderivative instruments designated and qualifying as cash flow hedge recorded in accumulated other comprehensive income (AOCI) and reclassified into earnings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 + Details
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- Definition Tabular disclosure of the location and fair value amounts of derivative instruments (and nonderivative instruments that are designated and qualify as hedging instruments) reported in the statement of financial position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 + Details
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- Definition Tabular disclosure of the notional amounts of outstanding derivative positions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
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