Summary of Warrant Activity (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Warrants Outstanding Shares
Warrants outstanding at beginning of the period	501,494	2,628,923	791,508	3,127,618
Exercised	(475,901)	(1,669,640)	(765,915)	(2,168,335)
Expired	(25,593)		(25,593)
Warrants outstanding at end of the period	0	959,283	0	959,283
Warrants exercisable at end of the period		959,283		959,283
Weighted Average Exercise Price
Warrants outstanding at beginning of the period	10.20	8.41	10.05	8.48
Exercised	10.32	7.62	10.12	7.91
Expired	7.92		7.92
Warrants outstanding at end of the period		9.78		9.78
Warrants exercisable at end of the period		9.78		9.78