Debt - Schedule of Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Current debt	$ 6,968	$ 128,459
Long term debt	110,507	10,759
Equipment financing loans | Equipment financing credit facility
Debt Instrument [Line Items]
Current debt	6,968	7,036
Long term debt	11,232	10,759
Capital Lease
Debt Instrument [Line Items]
Current debt	0	224
4.00% Convertible Debentures | Convertible debentures
Debt Instrument [Line Items]
Current debt	0	121,199
5.00% Convertible Debentures | Convertible debentures
Debt Instrument [Line Items]
Long term debt	$ 99,275	$ 0