Debt - Schedule of Debt (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Current debt	$ 57,476	$ 128,459
Long term debt	87,326	10,759
Line of Credit | Equipment financing credit facility
Debt Instrument [Line Items]
Current debt	7,341	7,036
Long term debt	13,641	10,759
Capital Lease
Debt Instrument [Line Items]
Current debt	0	224
4.00% Convertible Debentures | Convertible Debt
Debt Instrument [Line Items]
Current debt	50,135	121,199
5.00% Convertible Debentures | Convertible Debt
Debt Instrument [Line Items]
Long term debt	$ 73,685	$ 0