Share-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Compensation expense in stock compensation plans	$ 494,974	$ 155,069	$ 1,500,000	$ 482,897
Income tax benefit of stock compensation plans	173,241	54,274	536,725	169,014
Unrecognized compensation expense related to nonvested share-based compensation	3,100,000		3,100,000
Weighted average period of unrecognized compensation cost			1 year 8 months 12 days
Cash from option exercises	3,900,000	910,838	5,200,000	4,500,000
Tax benefit for tax deductions from option exercises	$ 177,717	$ 21,986	$ 241,391	$ 208,867