Debt - Schedule of Long-Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019
Debt Disclosure [Abstract]
Total debt	$ 145,000	$ 120,000
Long-term debt	145,000	120,000
Deferred debt costs and royalty liability, net of amortization	3,088	1,855
Long-term debt, less current portion	$ 148,088	$ 121,855