Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 329,812	$ 329,208
Less: Allowance for doubtful accounts	(3,652)	(3,755)
Accounts receivable, net	326,160	325,453
Accounts receivable - trade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	257,264	264,562
Accounts receivable - grants from outside parties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	23,052	33,003	20,900
Accounts receivable - insurance and other third-party claims [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 49,496	$ 31,643