Summary of Significant Accounting Policies - Summary of Revenue by Region (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Disaggregation Of Revenue [Line Items]
Revenue	$ 299,489	$ 271,893	$ 243,920
Service
Disaggregation Of Revenue [Line Items]
Revenue	$ 299,489	$ 271,893	$ 243,920
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	$ 217,242	$ 192,438	$ 176,120
United States | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	73.00%	71.00%	72.00%
United Kingdom
Disaggregation Of Revenue [Line Items]
Revenue	$ 63,023	$ 58,477	$ 49,386
United Kingdom | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	21.00%	22.00%	20.00%
Canada
Disaggregation Of Revenue [Line Items]
Revenue	$ 13,581	$ 14,293	$ 12,172
Canada | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	4.00%	5.00%	5.00%
Other
Disaggregation Of Revenue [Line Items]
Revenue	$ 5,643	$ 6,685	$ 6,242
Other | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Disaggregation Of Revenue [Line Items]
Percentage of Revenue	2.00%	2.00%	3.00%