Accounts Receivable - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, allowances for doubtful accounts	$ 21,000		$ 21,000	$ 23,000	$ 25,400
Bad debt expense			52,935	$ 9,934
MAT sales reversal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net sales reversal		$ 30,000
Accounts receivable reversal	(7,000)		80,000
Bad debt expense	$ (7,000)		$ 50,000