Convertible and Long-Term Debt Obligations - Zero-coupon Convertible Senior Notes due in 2020 - Additional Information (Detail) - Zero-coupon Convertible Senior Notes due in 2020 [Member] - Chief Executive Officer [Member]	Apr. 26, 2017 USD ($)
Debt Instrument [Line Items]
Debt conversion aggregate principal amount	$ 10,000,000
Loss on extinguishment of debt	$ 2,200,000