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The period of time prior to intended redemption that notice must be given.

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Principal amount received on stock transaction before deduction of issuance costs.

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The amount of the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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The price per share of the conversion feature embedded in the debt instrument.

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Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

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Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

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Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

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Cash received on stock transaction after deduction of issuance costs.

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Convertible debentures - Series E Debentures (Details) $ / shares in Units, $ in Thousands, $ in Millions	Feb. 02, 2018 CAD ($)	Jan. 29, 2018 CAD ($) item $ / shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Apr. 10, 2019 CAD ($)	Mar. 03, 2018 CAD ($)	Mar. 02, 2018 USD ($)
Convertible debentures
Accrued interest			$ 2.5	$ 2.6
Series E Debentures
Convertible debentures
Sale offering, principal amount		$ 100,000
Amount of underwriters option to purchase additional debentures		15,000
Sale of offering, principal amount after issuance costs		$ 94,700
Series E Debentures \| Maximum
Convertible debentures
Period of underwriters option to purchase		30 days
Series E Debentures \| Over-Allotment Option
Convertible debentures
Net proceeds from issuance of convertible debentures, after underwriting discounts and expenses	$ 15,000
Sale of offering, principal amount after issuance costs		$ 14,400
Series E Debentures \| 6.00% Debenture Due January 31, 2025
Convertible debentures
Conversion debt principal amount		$ 1,000
Conversion rate of the debentures (in Shares per Dollar)		238.0952
Conversion price of shares (in dollars per share) \| $ / shares		$ 4.20
Number of consecutive trading days used to determine weighted average trading price \| item		20
Number of days common stock price must exceed threshold percentage \| item		5
Series E Debentures \| 6.00% Debenture Due January 31, 2025 \| Maximum
Convertible debentures
Period of prior notice of redemption		60 days
Series E Debentures \| 6.00% Debenture Due January 31, 2025 \| Minimum
Convertible debentures
Period of prior notice of redemption		30 days
Debt instrument, redemption price threshold, percentage		125.00%
Series D Debentures
Convertible debentures
Notice to redeem remaining principal amount						$ 56,200
Series D Debentures \| 6.00% Debenture due December 2019
Convertible debentures
Accrued interest					$ 400
Notice to redeem remaining principal amount					$ 24,700
Series C Debentures
Convertible debentures
Notice to redeem remaining principal amount							$ 42.5