Net Loss Per Common Share - Additional Information (Detail) - $ / shares	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 15, 2013
Convertible Notes due 2018
Earnings Per Share [Line Items]
Debt instrument, interest rate, stated percentage, per annum	0.70%			0.75%
The Notes
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price, per share	$ 94.15	$ 94.15	$ 94.15
Convertible Notes due 2020
Earnings Per Share [Line Items]
Debt instrument, interest rate, stated percentage, per annum	1.50%			1.50%