Accounts Receivable Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 392,808	$ 375,993
Allowance for doubtful accounts	(12,869)	(12,070)
Accounts receivable, net	379,939	363,923
Accounts receivable - trade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	371,990	353,347
Accounts receivable - grants from outside parties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	9,981	10,652	$ 12,500
Accounts receivable - insurance and other third-party claims [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 10,837	$ 11,994