Financial instruments and fair value measurements (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	$ 4,702.0	$ 4,972.2
Fair value	4,819.7	5,124.2
Receivables facility
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	0.0	0.0
Fair value	0.0	0.0
Senior secured credit facilities: | Term loans | Euro
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	254.7	344.8
Fair value	255.7	346.5
Senior secured credit facilities: | Term loans | U.S. dollars
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	420.7	546.7
Fair value	421.0	548.1
Senior secured credit facilities: | U.S. dollar term loans | U.S. dollars
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	1,172.1	1,175.0
Fair value	1,174.3	1,178.7
Notes | 2.625% secured notes
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	763.2	795.0
Fair value	783.1	815.7
Notes | 3.875% unsecured notes
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	469.6	489.2
Fair value	496.7	515.0
Notes | 4.625 % unsecured notes
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	1,550.0	1,550.0
Fair value	1,617.2	1,648.7
Finance lease liabilities
Estimated Fair Value Of Financial Instruments [Line Items]
Carrying value	71.7	71.5
Fair value	$ 71.7	$ 71.5