Earnings (Loss) Per Common Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Numerator:
Net income (loss)	$ (6,397)	$ 4,877	$ 1,831	$ (497)	$ 1,533	$ 2,565	$ 1,002	$ 292	$ (186)	$ 5,392	$ 2,816
Denominator:
Weighted-average common shares outstanding (shares)									29,169	25,566	24,634
Basic earnings per common share (usd per share)	$ (0.22)	$ 0.17	$ 0.06	$ (0.02)	$ 0.06	$ 0.10	$ 0.04	$ 0.01	$ (0.01)	$ 0.21	$ 0.11
Numerator:
Net income (loss)	$ (6,397)	$ 4,877	$ 1,831	$ (497)	$ 1,533	$ 2,565	$ 1,002	$ 292	$ (186)	$ 5,392	$ 2,816
Denominator:
Weighted-average common shares outstanding (shares)									29,169	25,566	24,634
Incremental shares from stock-based compensation plans (shares)									0	571	395
Denominator for diluted earnings (loss) per common share (shares)									29,169	26,137	25,029
Diluted earnings per common share (usd per share)	$ (0.22)	$ 0.16	$ 0.06	$ (0.02)	$ 0.06	$ 0.10	$ 0.04	$ 0.01	$ (0.01)	$ 0.21	$ 0.11