Accounts Receivable - Company's Accounts Receivable and Securitized Accounts Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	$ 2,218,399	$ 1,825,515
Gross domestic securitized accounts receivable	741,000	591,000
Less allowance for doubtful accounts	(47,836)	(32,506)	$ (25,236)	$ (21,903)
Net accounts and securitized accounts receivable	2,170,563	1,793,009
Gross domestic accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	711,681	529,885
Gross foreign receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	$ 765,718	$ 704,630