Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2018 USD ($) Customer	Mar. 31, 2017 USD ($) Customer	Mar. 31, 2016 Customer
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Maturities of short term investment interest-bearing securities	90 days
Accounts receivable due period	30 days
Unbilled account receivables	$ 15,131,000	$ 14,579,000
Capitalized software development costs	27,679,000	25,721,000
Accumulated amortization of software development costs	88,567,000	78,952,000
Impairment of goodwill, intangible assets or other long-lived assets	0
Goodwill	36,814,000	36,814,000
Accumulated amortization of goodwill	$ 2,069,000	$ 2,069,000
Computer Software Property and Equipment [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Amortization period of computer software	5 years
Customer Concentration Risk [Member] | Sales Revenue, Net [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Maximum customer risk percentage	10.00%	10.00%	10.00%
Number of customer | Customer	0	0	0
Credit Concentration Risk [Member] | Accounts Receivable [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Maximum customer risk percentage	10.00%	10.00%
Number of customer | Customer	0	0
Private Equity Funds [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Investment	$ 2,250,000
Reduction to investments	1,169,000
Fair Value, Inputs, Level 2 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Transfer of assets	0
Fair Value, Inputs, Level 3 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Transfer of assets	$ 0