Revenues - Remaining performance obligation (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2020 USD ($)
Remaining performance obligation
Aggregate amount of transaction price allocated to remaining performance obligations	$ 36,302
Upfront payments
Unamortized upfront payments for services	$ 32,244
Amortization period for upfront payments for services	5 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-03-31
Remaining performance obligation
Remaining performance obligation, expected period of recognition	5 years