Accounts Receivable Securitization Programs (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) bank	Sep. 30, 2017 USD ($)	Sep. 30, 2018 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)
Qualitative And Quantitative Information Transferors Continuing Involvement [Line Items]
Interest paid	$ 44,800,000	$ 49,100,000	$ 131,300,000	$ 143,400,000
U.S. Accounts Receivable Securitization Program | U.S. Program
Qualitative And Quantitative Information Transferors Continuing Involvement [Line Items]
Number of banks involved in sale of fractional ownership interest of accounts receivable | bank			2
Level of eligible assets available under accounts receivable securitization program			$ 60,000,000
Amount available for accounts receivable securitization program	60,000,000		60,000,000
Amount utilized under accounts receivable securitization program	0		0			$ 0
U.S. Accounts Receivable Securitization Program | Maximum | U.S. Program
Qualitative And Quantitative Information Transferors Continuing Involvement [Line Items]
Maximum purchase limit for receivable interests under accounts receivable securitization program	60,000,000		60,000,000
European Accounts Receivable Securitization Program | European Program
Qualitative And Quantitative Information Transferors Continuing Involvement [Line Items]
Amount available for accounts receivable securitization program	85,500,000		85,500,000		€ 73,400,000
Amount utilized under accounts receivable securitization program	83,900,000		83,900,000		72,000,000		€ 0
European Accounts Receivable Securitization Program | Maximum | European Program
Qualitative And Quantitative Information Transferors Continuing Involvement [Line Items]
Maximum purchase limit for receivable interests under accounts receivable securitization program	93,100,000		93,100,000		€ 80,000,000
Accounts Receivable Securitization Programs
Qualitative And Quantitative Information Transferors Continuing Involvement [Line Items]
Interest paid	$ 200,000	$ 600,000	$ 400,000	$ 1,000,000