Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 210,194	$ 297,961
Research and development and other tax credit carryforwards	12,828	11,965
Accruals and reserves	22,406	26,222
Fixed assets and intangible assets	1,568	2,250
Other	12,996	12,454
Gross deferred tax assets	259,992	350,852
Valuation allowance	(227,686)	(315,092)
Total deferred tax assets	32,306	35,760
Intercompany debt	(29,130)	(25,841)
Other	(2,744)	(9,637)
Total deferred tax liabilities	(31,874)	(35,478)
Net deferred tax asset	$ 432	$ 282