Concentration of Revenue and Assets - Geographic concentration (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020
Concentration of Revenue and Assets
Revenue	$ 301,064	$ 319,024
Long-lived assets, net	517,833		$ 528,646
United States of America
Concentration of Revenue and Assets
Revenue	212,480	218,092
Long-lived assets, net	264,366		272,422
United Kingdom
Concentration of Revenue and Assets
Revenue	39,574	49,879
India
Concentration of Revenue and Assets
Long-lived assets, net	235,326		238,367
Rest Of World
Concentration of Revenue and Assets
Revenue	49,010	$ 51,053
Long-lived assets, net	$ 18,141		$ 17,857