Restructuring and other impairment charges - Expected costs to be incurred (Details) $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
2019 Footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Aggregate restructuring charges	$ 15.3
Restructuring expenses	14.5
Aggregate restructuring related charges	21.1
2019 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	56.0
Expected cash outlays	50.0
Expected capital expenditures	28.0
2019 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	63.0
Expected cash outlays	57.0
Expected capital expenditures	33.0
2018 Footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Aggregate restructuring charges	60.0
Restructuring expenses	9.5
Aggregate restructuring related charges	16.7
2018 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	103.0
Expected cash outlays	99.0
Expected capital expenditures	19.0
2018 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	133.0
Expected cash outlays	127.0
Expected capital expenditures	23.0
2014 Footprint realignment plan
Restructuring Cost and Reserve [Line Items]
Aggregate restructuring charges	13.6
Restructuring expenses	3.8
Aggregate restructuring related charges	36.0
2014 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	52.0
Expected cash outlays	42.0
Expected capital expenditures	26.0
2014 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	55.0
Expected cash outlays	46.0
Expected capital expenditures	27.0
Termination benefits \| 2019 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	16.0
Termination benefits \| 2019 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	18.0
Termination benefits \| 2018 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	60.0
Termination benefits \| 2018 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	70.0
Termination benefits \| 2014 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	13.0
Termination benefits \| 2014 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	13.0
Other costs \| 2019 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	2.0
Other costs \| 2019 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	2.0
Other costs \| 2018 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	3.0
Other costs \| 2018 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	4.0
Other costs \| 2014 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	1.0
Other costs \| 2014 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	2.0
Restructuring charges \| 2019 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	18.0
Restructuring charges \| 2019 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	20.0
Restructuring charges \| 2018 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	63.0
Restructuring charges \| 2018 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	74.0
Restructuring charges \| 2014 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	14.0
Restructuring charges \| 2014 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	15.0
Restructuring related charges \| 2019 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	38.0
Restructuring related charges \| 2019 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	43.0
Restructuring related charges \| 2018 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	40.0
Restructuring related charges \| 2018 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	59.0
Restructuring related charges \| 2014 Footprint realignment plan \| Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	38.0
Restructuring related charges \| 2014 Footprint realignment plan \| Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	$ 40.0

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Restructuring and Related Cost, Expected Cash Outlays

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Amount expected to be recognized in earnings for the specified restructuring cost.

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Discloses the amount charged against the accrued restructuring reserves, or earnings if not previously accrued, during the period for the specified type of restructuring cost.

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Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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