Computation of Basic and Diluted Net Income Per Common Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Numerator:
Net income	$ 478		$ 4,505		$ 518		$ 10,791
Adjustment for interest expense on convertible notes	(32)	[1]	104	[1]	(65)	[1]	212	[1]
Net income, as adjusted	$ 446		$ 4,609		$ 453		$ 11,003
Denominator:
Weighted average number of shares of common stock outstanding	6,940,831		6,863,904		6,934,182		6,856,310
Weighted average effect of assumed conversion of convertible notes	428,888		428,888		428,177		428,173
Weighted average effect of dilutive stock options and other stock compensation	115,686		172,468		131,766		160,908
Weighted average number of shares of common stock outstanding, as adjusted	7,485,405		7,465,260		7,494,125		7,445,391
Net income per common share:
Net income per common share - Basic	$ 0.07		$ 0.66		$ 0.07		$ 1.57
Net income per common share - Diluted	$ 0.06		$ 0.62		$ 0.06		$ 1.48

[1] The adjustment for interest expense on convertible notes is net of tax. For the three and six months ended June 30, 2013, the adjustment is a reduction to net income as a result of our annualized effective tax rate for 2013.