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Significant transactions (Details) - USD ($) $ in Millions				3 Months Ended	9 Months Ended
Significant transactions (Details) - USD ($) $ in Millions	Sep. 30, 2026	Jan. 01, 2026	Oct. 03, 2025	Dec. 31, 2025	Sep. 30, 2026
Business Interruption Loss [Line Items]
Assets held for sale	$ 0.0			$ 115.2	$ 0.0
Goodwill	46.0			$ 0.0	46.0
Assist America
Business Interruption Loss [Line Items]
Aggregate consideration		$ 44.0
Goodwill	18.6				18.6
World Nomads
Business Interruption Loss [Line Items]
Aggregate consideration	48.0
Goodwill	$ 27.5				27.5
Arcadian Holdings Limited
Business Interruption Loss [Line Items]
Equity method investment, amount sold			$ 140.4
Equity method investment, expected gain (loss) on disposal					$ 25.2
Variable Interest Entity, Primary Beneficiary, Arcadian Risk Capital Ltd
Business Interruption Loss [Line Items]
VIE, ownership percentage			49.00%	49.00%