Basis of Preparation and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Mar. 31, 2019 USD ($) Customer shares	Mar. 31, 2018 USD ($) Customer shares	Mar. 31, 2017 USD ($) Customer shares	Apr. 01, 2017 USD ($)
Summary Of Significant Accounting Policy [Line Items]
Expected dividend yield	0.00%
Excess tax benefits related to restricted stock unit vestings or stock option exercises, decrease in financing activities			$ 12,038
Excess tax benefits related to restricted stock unit vestings or stock option exercises, increase in operating activities			$ 12,038
Adoption of ASU 2016-09 in Fiscal 2018
Summary Of Significant Accounting Policy [Line Items]
Cumulative effect to increase retained earnings and deferred tax assets				$ 76,400
Excess tax benefit	$ 69,300	$ 31,000
Excess tax benefits related to restricted stock unit vestings or stock option exercises, decrease in financing activities		31,000
Excess tax benefits related to restricted stock unit vestings or stock option exercises, increase in operating activities	$ 69,300	$ 31,000
Increase additional paid in capital				1,800
Increase deferred tax assets				700
Decrease retained earnings				$ (1,100)
Net Income Per Share - Anti-dilutive securities
Summary Of Significant Accounting Policy [Line Items]
Shares excluded from the calculation of diluted weighted average shares outstanding | shares	64,000	155,000	24,000
Customer Concentration Risk | Total Revenues
Summary Of Significant Accounting Policy [Line Items]
Number of customers that accounted for more than 10% of total revenues / receivables | Customer	0	0	0
Customer Concentration Risk | Total Accounts Receivable
Summary Of Significant Accounting Policy [Line Items]
Number of customers that accounted for more than 10% of total revenues / receivables | Customer	0	0