Activity of Non-Vested Stock Options (Detail) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of shares
Nonvested common stock options, beginning balance	81,400	673,833	872,373
Common stock options granted			205,000
Common stock options vested	(31,400)	(592,433)	(383,208)
Common stock options forfeited	(50,000)		(20,332)
Nonvested common stock options, ending balance		81,400	673,833
Weighted Average Exercise Price Per Share
Nonvested common stock options, beginning balance	$ 7.62	$ 6.59	$ 5.41
Common stock options granted			9.52
Common stock options vested	3.84	6.29	5.47
Common stock options forfeited	$ 10.00		3.62
Nonvested common stock options, ending balance		$ 7.62	$ 6.59