Debt - Schedule of Payments on Outstanding Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Debt Instrument [Line Items]
Total - 2013	$ 11,846
Total - 2014	9,211
Total - 2015	7,995
Total - 2016	6,203
Total - 2017	79,930
Line of Credit | Equipment financing loans
Debt Instrument [Line Items]
Principal - 2013	6,968
Interest - 2013	1,003
Principal - 2014	4,732
Interest - 2014	604
Principal - 2015	3,798
Interest - 2015	322
Principal - 2016	2,208
Interest - 2016	120
Principal - 2017	494
Interest - 2017	9
5.00% Convertible Debentures | Convertible Debt
Debt Instrument [Line Items]
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