Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2017
Income Tax Contingency [Line Items]
U.S. statutory federal income tax rate, percent	21.00%	35.00%	31.60%
Cumulative effect adjustment related to unrecognized excess tax benefits on share based compensation				$ 58,700,000
Valuation allowance	$ 29,049,000		$ 29,049,000		$ 17,728,000
Impact on effective tax rate	49,500,000		49,500,000
Accrued interest or penalties associated with uncertain tax positions	0		0		$ 0
Provisional income tax expense			5,300,000
United States [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	697,800,000		$ 697,800,000
Operating loss carryforwards expiration beginning year			2021
United States [Member] | Earliest Tax Year [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination			2015
United States [Member] | Latest Tax Year [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination			2017
United States [Member] | Research [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward amount	135,800,000		$ 135,800,000
United States [Member] | Research [Member] | Earliest Tax Year [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards expiration beginning year			2026
State [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	637,800,000		$ 637,800,000
Operating loss carryforwards expiration beginning year			2019
State [Member] | Earliest Tax Year [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination			2014
State [Member] | Latest Tax Year [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination			2017
State [Member] | Research [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward amount	$ 130,000,000		$ 130,000,000
State [Member] | Research [Member] | Earliest Tax Year [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards expiration beginning year			2019
Foreign [Member] | Earliest Tax Year [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination			2014
Foreign [Member] | Latest Tax Year [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination			2017