Revenue recognition - Contract assets and liabilities (Details) - Madison Industries IAQ Solutions Corporation - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Disaggregation of Revenue [Line Items]
Contract assets, current (included in accounts receivable, net)	$ 28.9	$ 43.3
Total contract assets	28.9	43.3
Contract liabilities, current (included in customer deposits and deferred revenue)	(123.1)	(128.3)
Contract liabilities, long-term (included in other long-term liabilities)	(13.2)	(13.3)
Total contract liabilities	(136.3)	(141.6)
Net contract assets (liabilities)	$ (107.4)	$ (98.3)