Revenue from contracts with customers Remaining performance obligations (Details 3) $ in Millions	Dec. 31, 2019 USD ($)
Remaining performance obligation, expected timing of satisfaction, start date: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	$ 1,500.0
Remaining performance obligation, expected timing of satisfaction, start date: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	229.4
Remaining performance obligation, expected timing of satisfaction, start date: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	259.3
Remaining performance obligation, expected timing of satisfaction, start date: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	$ 2,000.0