Receivables (Schedule of Trade Accounts Receivables Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts receivable - trade	$ 418,064	$ 330,855
Allowance for doubtful accounts	(1,062)	(7,393)	$ (8,468)	$ (6,505)
Accounts receivable - trade, net	$ 417,002	$ 323,462

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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