Convertible Notes, Long-Term Debt and Credit Facility Convertible Notes, Long-Term Debt and Credit Facility (Revolving Credit Facility) (Details) (USD $)			12 Months Ended
	Dec. 31, 2013 Revolving Credit Facility [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Dec. 31, 2013 Line of Credit [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 Term loan [Member]	Dec. 31, 2013 Letter of Credit [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 PNC Bank base lending rate [Member] Line of Credit [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 LIBOR [Member] Line of Credit [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 Minimum [Member] PNC Bank base lending rate [Member] Line of Credit [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 Minimum [Member] PNC Bank base lending rate [Member] Term loan [Member]	Dec. 31, 2013 Minimum [Member] LIBOR [Member] Line of Credit [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 Maximum [Member] PNC Bank base lending rate [Member] Line of Credit [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 Maximum [Member] PNC Bank base lending rate [Member] Term loan [Member]	Dec. 31, 2013 Maximum [Member] LIBOR [Member] Line of Credit [Member] Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 75,000,000.0		$ 10,000,000
Maturity date				May 10, 2018
Basis spread on variable rate								0.50%	1.25%	1.50%	1.00%	1.75%	2.00%
Base lending rate							3.25%
Monthly facility fee			0.25%
Amount borrowed	16,272,000	0	16,300,000			1,300,000	15,000,000
Interest Rate at Period End						3.75%	1.67%
Credit facility, current borrowing capacity			$ 71,900,000