Earnings per Share - Additional Information (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Earnings Per Share [Line Items]
Series A Preferred stock, par value (in usd per share)	$ 0.001		$ 0.001		$ 0.001
Assumed average market price per share exercise of warrants treasury method (in usd per share)	37.93	$ 31.57	42.22	$ 28.96
Series A Convertible Preferred Stock
Earnings Per Share [Line Items]
Series A Preferred stock, par value (in usd per share)	$ 0.001		$ 0.001