Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 316,238	$ 265,642
Less: Allowance for doubtful accounts	(2,956)	(2,693)
Accounts receivable, net	313,282	262,949
Accounts receivable - trade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	264,958	214,936
Accounts receivable - grants [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	33,183	26,794
Accounts receivable - insurance claims [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 18,097	$ 23,912