Fair Value Measurement - Additional Information (Detail) - USD ($)		3 Months Ended												12 Months Ended
	Jan. 05, 2015	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities measured with fair value		$ 120,848,000												$ 120,848,000
Redeemable Convertible preferred stock, shares issued		600,000				0								600,000	0
Net income (loss) attributable to common and participating stockholders		$ 5,568,000	$ (8,419,000)	$ (77,983,000)	$ 1,253,000	$ (9,573,000)	$ (1,299,000)	$ 17,322,000	$ (12,835,000)	$ 7,516,000	$ (878,000)	$ (2,484,000)	$ (3,816,000)	$ (79,581,000)	$ (6,385,000)	$ 338,000
Maximum [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percentage of closing stock price														10.00%
Estimated net loss														$ 53,000,000
Maximum [Member] | Volatility Assumption [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percentage of closing stock price														10.00%
Estimated net loss														$ 9,900,000
Maximum [Member] | Transaction Occurring Assumption [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percentage of closing stock price														10.00%
Estimated net loss														$ 13,400,000
Minimum [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Preferred stock liquidation preference per share						$ 10.00									$ 10.00
Percentage of closing stock price														10.00%
Estimated net loss														$ 51,800,000
Minimum [Member] | Volatility Assumption [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percentage of closing stock price														10.00%
Estimated net loss														$ 7,600,000
Minimum [Member] | Transaction Occurring Assumption [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percentage of closing stock price														10.00%
Estimated net loss														$ 13,400,000
Redeemable Convertible Series B Preferred Stock [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Capital	$ 600,000,000
Redeemable Convertible preferred stock, shares issued	600,000	600,000				0				0				600,000	0	0
Preferred stock liquidation preference per share	$ 1,000
Preferred stock dividend rate calculated on interest rate	3.00%
Conversion floor price of common stock		$ 1.75												$ 1.75
Redeemable Convertible Series B Preferred Stock [Member] | Maximum [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Common stock value per share		$ 2.25												$ 2.25
Redeemable Convertible Series B Preferred Stock [Member] | Minimum [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Preferred stock liquidation preference per share	$ 1,000
Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities measured with fair value						$ 0									$ 0