Net Income Per Common Share (Computation of Net Income Per Common Share) (Details) (USD $) In Thousands, except 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 (loss) income	$ (2,869)	$ (1,711)	$ 478	$ 40	$ 1,081	$ 2,745	$ 4,505	$ 6,286	$ (4,062)	$ 14,617		$ 18,122
Adjustment for interest expense on convertible notes										458		119
Net (loss) income, as adjusted									$ (4,062)	$ 15,075		$ 18,241
Denominator:
Weighted average number of shares of common stock outstanding									6,950,976	6,874,669		6,826,490
Weighted average effect of dilutive stock options and other stock compensation										151,223		153,397
Weighted average effect of assumed conversion of convertible notes										428,138	[1]	158,937	[1]
Weighted average number of shares of common stock outstanding, as adjusted									6,950,976	7,454,030		7,138,824
Net (loss) income per common share:
Net (loss) income per common share - Basic	$ (0.41)	$ (0.25)	$ 0.07	$ 0.01	$ 0.16	$ 0.40	$ 0.66	$ 0.92	$ (0.58)	$ 2.13		$ 2.65
Net (loss) income per common share - Diluted	$ (0.41)	$ (0.25)	$ 0.06	$ 0.01	$ 0.16	$ 0.38	$ 0.62	$ 0.86	$ (0.58)	$ 2.02		$ 2.56

[1] The weighted average for the assumed conversion of the Notes was calculated from the August 18, 2011 issuance.