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Income taxes: - Loss carry-forwards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($)
Income taxes
Net operating loss carry-forwards	$ 1,200.0
UNITED STATES
Income taxes
Net operating loss carry-forwards	131.7
Europe
Income taxes
Net operating loss carry-forwards	1,000.0
Carry-forwards not limited for use	883.6
Carry-forwards limited for use	156.7
Other than Europe
Income taxes
Net operating loss carry-forwards	$ 32.7

X

- Definition

Amount of operating loss carryforwards not available for use in the future.

+ References

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- Definition

The amount of operating loss carryforwards which are not subject to expiration dates.

+ References

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X

- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-3

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-3

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