Summary of Warrant Activity (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Warrants Outstanding Shares
Warrants outstanding at beginning of year	3,127,618	4,867,477	4,944,241
Granted
Exercised	(2,336,110)	(1,739,859)	(76,764)
Expired
Warrants outstanding at end of year	791,508	3,127,618	4,867,477
Exercisable at end of year	791,508	3,127,618	4,867,477
Weighted Average Exercise Price
Warrants outstanding at beginning of year	8.48	9.54	9.48
Granted
Exercised	7.96	11.81	8.34
Expired
Warrants outstanding at end of year	10.05	8.48	9.54
Exercisable at end of year	10.05	8.48	9.54