Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 266,217	$ 265,642
Less: Allowance for doubtful accounts	(2,688)	(2,693)
Accounts receivable, net	263,529	262,949
Accounts receivable - trade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	230,161	214,163
Accounts receivable - grants [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	20,898	25,036	17,800
Accounts receivable - insurance claims [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 15,158	$ 26,443