Stockholders' Equity - Additional Information (Detail) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Nov. 24, 2008
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Series A Junior Participating Preferred Stock
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)			$ 0.01
Share price (in dollars per share)			$ 100
Percentage of preferred stock exercisable			15.00%