Accounts Receivable Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 329,208	$ 265,642
Less: allowance for doubtful accounts	(3,755)	(2,693)	(2,807)	(3,079)
Accounts receivable, net	325,453	262,949
Accounts receivable - trade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	264,562	216,694
Accounts receivable - grants from outside parties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	33,003	25,036	20,800
Accounts receivable - insurance and other third party claims [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 31,643	$ 23,912