Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue
Revenue	$ 1,312,283	$ 1,247,863
Time-and-materials
Disaggregation of Revenue
Revenue	771,312	738,309
Fixed-price
Disaggregation of Revenue
Revenue	540,971	509,554
Application outsourcing
Disaggregation of Revenue
Revenue	729,821	672,636
Consulting
Disaggregation of Revenue
Revenue	582,462	575,227
Banking Financial Services and Insurance
Disaggregation of Revenue
Revenue	752,965	776,955
Communications and Technology
Disaggregation of Revenue
Revenue	449,661	360,967
Media & Information and Other
Disaggregation of Revenue
Revenue	109,657	109,941
North America
Disaggregation of Revenue
Revenue	968,117	884,114
Europe
Disaggregation of Revenue
Revenue	230,965	261,967
Rest Of World
Disaggregation of Revenue
Revenue	$ 113,201	$ 101,782