Commitment and contingencies - Environmental Liabilities Balance Sheet Information (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Other accrued expenses
Other Commitments [Line Items]
Current environmental liabilities	$ 26.6	$ 25.0
Other long-term liabilities
Other Commitments [Line Items]
Long-term environmental liabilities	$ 56.4	$ 53.7

Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable in twelve months or in the next operating cycle if longer.

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