Long-Term Debt - Summary of Long-Term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total principal amount	$ 147,985		$ 143,250
Less: unamortized discount and issuance costs	(9,122)		(13,821)
Total long-term debt	138,863		129,429
Senior Notes [Member]
Debt Instrument [Line Items]
Total principal amount	40,250		40,250
Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Total principal amount	89,990		$ 103,000
Less: unamortized discount and issuance costs		$ 1,591
4% Promissory Note [Member]
Debt Instrument [Line Items]
Total principal amount	8,821
3.75% Promissory Note [Member]
Debt Instrument [Line Items]
Total principal amount	$ 8,924