Accounts Receivable Securitization (Details) - USD ($) $ in Thousands					3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018	Jul. 11, 2018	Mar. 31, 2019	Mar. 31, 2018
Servicing Liabilities at Fair Value [Line Items]
Program fees					$ 2,000	$ 2,000
2018 RSA [Member]
Servicing Liabilities at Fair Value [Line Items]
Effective date				Jul. 11, 2018
Final maturity date				Jul. 09, 2021
Receivables Sales Agreement, Borrowing Capacity				$ 325,000
Accordion Option Accounts Receivable Securitization	[1]			$ 175,000
Unused commitment fee rate	[2]			20 to 40 basis points
Program fees on outstanding balances	[3]			one-month LIBOR + 80 to 100 basis points
RSA Borrowing Base		$ 280,700	$ 325,000		280,700
Accounts receivable securitization	[4]	(175,000)	(240,000)		(175,000)
Letters of Credit Outstanding, Amount		(70,649)	(70,900)		(70,649)
Availability under accounts receivable securitization facilities		$ 35,051	$ 14,100		$ 35,051
Debt Instrument, Interest Rate During Period		3.40%	3.20%

[1] The accordion option increases the maximum borrowing capacity, subject to participation of the purchasers.

[2] The 2018 RSA commitment fee rate is based on the percentage of the maximum borrowing capacity utilized.

[3] The 2018 RSA program fee is based on the Company's consolidated total net leverage ratio.

[4] Outstanding borrowings are included in "Accounts receivable securitization" in the condensed consolidated balance sheets. Interest accrued on the aggregate principal balance at a rate of 3.4% and 3.2% as of March 31, 2019 and December 31, 2018, respectively.