Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Customer Accounts Receivable and Note Receivable [Line Items]
Customer Accounts Receivable and Note Receivable	$ 27,850	$ 20,000
Accounts receivable	7,124,677	6,798,943
Allowances for doubtful accounts	(54,048)	(52,256)
Accounts receivable, net	$ 7,070,629	$ 6,746,687