Common Stock - Additional Information (Detail) $ / shares in Units, $ in Thousands			12 Months Ended
	Jun. 19, 2014 USD ($)	Apr. 02, 2014 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) vote_per_share $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) shares
Common Stock Disclosure [Line Items]
Stock price (in dollars per share) | $ / shares		$ 11.00
Common stock, shares authorized			150,000,000	150,000,000
Common stock, par value | $ / shares		$ 0.001	$ 0.001	$ 0.001
Holder of each share of common stock entitled vote | vote_per_share			1
Common stock, shares, issued		5,750,000	81,734,078	79,388,069
Proceeds from issuance of common stock in a public offering, net of underwriting discounts and commission | $		$ 59,200	$ 0	$ 59,209	$ 0
Convertible Senior Subordinated Notes | Early Conversion Payment
Common Stock Disclosure [Line Items]
Number of common shares issued upon early conversion of notes				2,743,475	5,541,597
2018 Notes
Common Stock Disclosure [Line Items]
Aggregate amount of debt | $				$ 22,600	$ 44,200
2018 Notes | Convertible Senior Subordinated Notes
Common Stock Disclosure [Line Items]
Aggregate amount of debt | $	$ 17,500
2018 Notes | Convertible Senior Subordinated Notes | Early Conversion Payment
Common Stock Disclosure [Line Items]
Number of common shares issued upon early conversion of notes				2,743,475	5,541,597