Summary of Warrant Activity (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Warrants Outstanding Shares
Warrants outstanding at beginning of the period	791,508	3,127,618
Exercised	(157,768)	(33,942)
Warrants outstanding at end of the period	633,740	3,093,676
Warrants exercisable at end of the period	633,740	3,093,676
Weighted Average Exercise Price
Warrants outstanding at beginning of the period	10.50	8.48
Exercised	10.59	8.16
Warrants outstanding at end of the period	9.92	8.49
Warrants exercisable at end of the period	9.92	8.49