Description of Business and Basis of Presentation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Schedule of computation of basic and diluted net income (loss) per share
Net income	$ 3,405	$ 31	$ 3,127	$ (921)
Effect of assumed conversion of convertible debentures
Weighted-average common shares outstanding	28,858	28,672	28,842	28,397
Weighted-average common shares outstanding, assuming dilution	28,860	28,780	28,859	28,397
Net income per share
Basic	$ 0.12	$ 0.00	$ 0.11	$ (0.03)
Diluted	$ 0.12	$ 0.00	$ 0.11	$ (0.03)
Stock Options
Effect of assumed conversion of convertible debentures
Effect of potentially dilutive securities	0	85	12	0
Restricted Stock [Member]
Effect of assumed conversion of convertible debentures
Effect of potentially dilutive securities	2	5	5	0
Restricted Stock Unit
Effect of assumed conversion of convertible debentures
Effect of potentially dilutive securities	0	0	0	0
Employee Stock Purchase Plan
Effect of assumed conversion of convertible debentures
Effect of potentially dilutive securities	0	18	0	0