Deferred revenues - Remaining Performance Obligation (Details) $ in Billions	Mar. 31, 2021 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contracted not recognized revenue	$ 2.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contracted not recognized revenue	$ 1.7
Contracted not recognized revenue, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contracted not recognized revenue	$ 0.4
Contracted not recognized revenue, period	1 year