Accounts Receivable Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 457,225	$ 436,360
Allowance for doubtful accounts	(13,057)	(10,055)
Accounts receivable, net	444,168	426,305
Accounts receivable - trade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	406,770	397,255
Accounts receivable - grants from outside parties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	18,748	19,376	$ 10,900
Accounts receivable - insurance and other third-party claims [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 31,707	$ 19,729