Debt (Details Textual) (USD $)	3 Months Ended				3 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Revolving Credit Facility	Mar. 31, 2013 2012 Credit Agreement	Mar. 31, 2013 2012 Credit Agreement Revolving Credit Facility	Mar. 31, 2013 2012 Credit Agreement Term Loan	Dec. 31, 2012 2012 Credit Agreement Term Loan	Mar. 31, 2013 2010 Convertible Notes	Dec. 31, 2012 2010 Convertible Notes
Debt (Textual) [Abstract]
Payments on long-term debt	$ 3,750,000	$ 7,000,000
Outstanding borrowings				0
Amount available under revolving credit facility				100,000,000
Credit Agreements						100,000,000
Cash payable on conversion of 2010 Convertible Notes									100.00%
Maturity date of 2010 Convertible Notes									Mar. 01, 2017
Maturity period							2017-11
2012 Credit Agreement Early Termination Date					Dec. 01, 2016
Term loan description							LIBOR plus 2.00%
Term Loan Libor rate							2.00%
Combined rate of interest on principle balance							2.29%	2.31%
Interest rate on senior subordinated convertible notes									3.00%
Unamortized OID	$ 24,003,000		$ 25,302,000						$ 24,003,000	$ 25,302,000