Long-term Debt and Short-term Borrowings (Notes Payable and Long-term Debt) (Details) AUD in Millions	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 22, 2016 USD ($)	May 02, 2016 USD ($)	May 02, 2016 AUD
Debt Instrument [Line Items]
Total debt	$ 939,500,000	$ 703,500,000
Current portion	43,200,000	68,500,000
Debt issuance costs, unamortized	7,100,000	7,300,000
Long-term debt, net	889,200,000	627,700,000
Other borrowings
Debt Instrument [Line Items]
Total debt	600,000	600,000
Senior Secured Notes | Euro Senior Secured Term Loan A, due January 2022 (floating interest rate of 1.50% at December 31, 2017)
Debt Instrument [Line Items]
Total debt	$ 345,000,000	0
Line of Credit Facility, Interest Rate at Period End	1.50%
Senior Secured Notes | U.S. Dollar Senior Secured Term Loan A, due April 2020 (floating interest rate of 2.27% at December 31, 2016)
Debt Instrument [Line Items]
Total debt	$ 0	$ 81,000,000
Line of Credit Facility, Interest Rate at Period End		2.27%
Senior Secured Notes | Australian Dollar Senior Secured Term Loan A, due January 2022 (floating interest rate of 3.29% at December 31, 2017)
Debt Instrument [Line Items]
Total debt	$ 60,000,000	$ 0
Line of Credit Facility, Interest Rate at Period End	3.29%
Senior Secured Notes | Australian Dollar Senior Secured Term Loan A, due April 2020 (floating interest rate of 3.25% at December 31, 2016)
Debt Instrument [Line Items]
Total debt	$ 0	$ 70,300,000		$ 76,600,000	AUD 100.0
Line of Credit Facility, Interest Rate at Period End		3.25%
Senior Secured Notes | U.S. Dollar Senior Secured Revolving Credit Facility, due January 2022 (floating interest rate of 3.53% at December 31, 2017)
Debt Instrument [Line Items]
Total debt	$ 48,900,000	$ 0
Line of Credit Facility, Interest Rate at Period End	3.53%
Senior Secured Notes | U.S. Dollar Senior Secured Revolving Credit Facility, due April 2020 (floating interest rate of 2.59% at December 31, 2016)
Debt Instrument [Line Items]
Total debt	$ 0	$ 63,700,000
Line of Credit Facility, Interest Rate at Period End		2.59%
Senior Secured Notes | Australian Dollar Senior Secured Revolving Credit Facility, due January 2022 (floating interest rate of 3.28% at December 31, 2017)
Debt Instrument [Line Items]
Total debt	$ 85,000,000	$ 0
Line of Credit Facility, Interest Rate at Period End	3.28%
Senior Secured Notes | Australian Dollar Senior Secured Revolving Credit Facility, due April 2020 (floating interest rate of 3.27% at December 31, 2016)
Debt Instrument [Line Items]
Total debt	$ 0	$ 87,900,000		$ 116,400,000	AUD 152.0
Line of Credit Facility, Interest Rate at Period End		3.27%
Senior Notes | Senior Unsecured Notes, due December 2024 (fixed interest rate of 5.25%)
Debt Instrument [Line Items]
Total debt	$ 400,000,000	$ 400,000,000	$ 400,000,000.0
Stated percentage	5.25%	5.25%