Convertible and Long-Term Debt Obligations - 2018 Notes, Bond Hedges and Warrant Transactions - Additional Information (Detail) - Senior Notes [Member] - 1.50% Convertible Senior Notes due in 2018 ("2018 Notes") [Member]	3 Months Ended
	Mar. 31, 2018 USD ($) shares
Debt Instrument [Line Items]
Debt conversion aggregate principal amount	$ 5,200,000
Convertible instrument exchanged for cash	$ 5,200,000
Convertible instrument, shares issued | shares	25,745
Maximum [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt	$ (100,000)