Reconciliation of Shares Used to Determine Net Income per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share Disclosure [Line Items]
Net income (loss)	$ (9,115)	$ 2,194	$ (4,312)	$ 9,837
Weighted average number of shares - basic	25,070,386	23,928,081	24,751,674	23,834,685
Weighted average number of shares outstanding - diluted	25,070,386	26,566,674	24,751,674	26,241,273
Warrants
Earnings Per Share Disclosure [Line Items]
Weighted average number of shares underlying	0	398,492	0	297,826
Options
Earnings Per Share Disclosure [Line Items]
Weighted average number of shares underlying	0	2,240,101	0	2,108,762