Summary of Information about Warrants Outstanding (Detail)	6 Months Ended
	Jun. 30, 2013
Class of Warrant or Right [Line Items]
Outstanding Warrants	2,628,923
Exercisable Warrants	2,628,923
$6.96
Class of Warrant or Right [Line Items]
Warrants Outstanding, Issue Date	Jan. 30, 2009
Exercise Price of warrants issued	6.96
Outstanding Warrants	1,604,049
Warrant expiration date	Jul. 30, 2014
Weighted Average Remaining Contractual Life (Years)	1 year 1 month 6 days
Exercisable Warrants	1,604,049
$8.70
Class of Warrant or Right [Line Items]
Warrants Outstanding, Issue Date	Jan. 30, 2009
Exercise Price of warrants issued	8.70
Outstanding Warrants	356
Warrant expiration date	Jan. 30, 2014
Weighted Average Remaining Contractual Life (Years)	7 months 6 days
Exercisable Warrants	356
$10.68
Class of Warrant or Right [Line Items]
Warrants Outstanding, Issue Date	Aug. 25, 2009
Exercise Price of warrants issued	10.68
Outstanding Warrants	1,024,518
Warrant expiration date	Aug. 31, 2014
Weighted Average Remaining Contractual Life (Years)	1 year 2 months 12 days
Exercisable Warrants	1,024,518