Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Contingency [Line Items]
Unrealized excess tax benefits associated with share based compensation	$ 58,700,000
Realized excess tax benefits	0
Valuation allowance	17,728,000	$ 17,089,000
Impact on effective tax rate	40,200,000
Accrued interest or penalties associated with uncertain tax positions	0	$ 0
Tax Credit Carryforward Alternative Minimum Tax [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward amount	400,000
Tax Credit Carryforward Foreign [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward amount	$ 1,300,000
Tax credit carryforwards expiration beginning date	Apr. 01, 2020
United States [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 673,600,000
Operating loss carryforwards expiration beginning date	Apr. 01, 2019
Tax years subject to examination	2014
United States [Member] | Research [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward amount	$ 109,600,000
United States [Member] | Research [Member] | Minimum [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards expiration beginning date	Apr. 01, 2025
State [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 556,000,000
Operating loss carryforwards expiration beginning date	Apr. 04, 2015
Tax years subject to examination	2013
State [Member] | Research [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward amount	$ 113,800,000
State [Member] | Research [Member] | Minimum [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards expiration beginning date	Apr. 01, 2017
Foreign [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination	2013