Debt - Schedule of Payments on Outstanding Debt (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
Debt Instrument [Line Items]
Total - 2012 (Six Months)	$ 58,094
Total - 2013	11,387
Total - 2014	8,946
Total - 2015	7,730
Total - 2016	5,937
Total - 2017	79,427
Line of Credit | Equipment financing credit facility
Debt Instrument [Line Items]
Principal - 2012 (Six Months)	3,999
Interest - 2012 (Six Months)	658
Principal - 2013	6,571
Interest - 2013	941
Principal - 2014	4,515
Interest - 2014	556
Principal - 2015	3,567
Interest - 2015	288
Principal - 2016	1,961
Interest - 2016	101
Principal - 2017	370
Interest - 2017	6
4.00% Convertible Debentures | Convertible Debt
Debt Instrument [Line Items]
Principal - 2012 (Six Months)	50,490
Interest - 2012 (Six Months)	1,010
Principal - 2013	0
Interest - 2013	0
Principal - 2014	0
Interest - 2014	0
Principal - 2015	0
Interest - 2015	0
Principal - 2016	0
Interest - 2016	0
Principal - 2017	0
Interest - 2017	0
5.00% Convertible Debentures | Convertible Debt
Debt Instrument [Line Items]
Principal - 2012 (Six Months)	0
Interest - 2012 (Six Months)	1,937
Principal - 2013	0
Interest - 2013	3,875
Principal - 2014	0
Interest - 2014	3,875
Principal - 2015	0
Interest - 2015	3,875
Principal - 2016	0
Interest - 2016	3,875
Principal - 2017	77,490
Interest - 2017	$ 1,937