Summary of Significant Accounting Policies - Summary of Revenue by Region (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Revenue	$ 271,893	$ 243,920	$ 305,463
Service
Disaggregation Of Revenue [Line Items]
Revenue	$ 271,893	$ 243,920	$ 305,463
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Service
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	100.00%	100.00%	100.00%
United States
Disaggregation Of Revenue [Line Items]
Revenue	$ 192,438	$ 176,120	$ 241,769
United States | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	71.00%	72.00%	79.00%
United Kingdom
Disaggregation Of Revenue [Line Items]
Revenue	$ 58,477	$ 49,386	$ 41,770
United Kingdom | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	22.00%	20.00%	14.00%
Canada
Disaggregation Of Revenue [Line Items]
Revenue	$ 14,293	$ 12,172	$ 14,481
Canada | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	5.00%	5.00%	5.00%
Other
Disaggregation Of Revenue [Line Items]
Revenue	$ 6,685	$ 6,242	$ 7,443
Other | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	2.00%	3.00%	2.00%
International
Disaggregation Of Revenue [Line Items]
Revenue	$ 79,455	$ 67,800	$ 63,694
International | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	29.00%	28.00%	21.00%