Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 354,364	$ 329,208
Less: Allowance for doubtful accounts	(5,455)	(3,755)
Accounts receivable, net	348,909	325,453
Accounts receivable - trade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	294,851	264,562
Accounts receivable - grants from outside parties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	29,305	33,003	33,200
Accounts receivable - insurance and other third-party claims
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 30,208	$ 31,643