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Debt (Details) € in Thousands	3 Months Ended		9 Months Ended
Debt (Details) € in Thousands	Sep. 30, 2018 USD ($) Rate	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Rate	Sep. 30, 2017 USD ($)	Sep. 30, 2018 EUR (€) Rate
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 495,653,000		$ 495,653,000
Unamortized Debt Issuance Expense	(1,285,000)		(1,285,000)
Total debt	1,044,647,000		1,044,647,000
Debt, Current	55,753,000		55,753,000
Long-term Debt	988,894,000		988,894,000
Gain (Loss) on Derivative Used in Net Investment Hedge, after Tax	(10,100,000)	$ 7,100,000	(4,600,000)	$ 10,500,000
Line of Credit Facility, Remaining Borrowing Capacity	601,000,000		601,000,000
Us Dollar Amounts Member
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	349,050,000		349,050,000
Unamortized Debt Issuance Expense	(950,000)		(950,000)
Total debt	792,840,000		792,840,000
Debt, Current	14,000		14,000
Long-term Debt	792,826,000		792,826,000
Other Principal Trading Currencies [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	146,603,000		146,603,000
Unamortized Debt Issuance Expense	(335,000)		(335,000)
Total debt	251,807,000		251,807,000
Debt, Current	55,739,000		55,739,000
Long-term Debt	$ 196,068,000		$ 196,068,000
3.67% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	3.67%		3.67%		3.67%
Debt Instrument, Maturity Date			Dec. 17, 2022
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 50,000,000		$ 50,000,000
3.67% Senior Notes [Member] \| Us Dollar Amounts Member
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	50,000,000		50,000,000
3.67% Senior Notes [Member] \| Other Principal Trading Currencies [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 0		$ 0
4.10% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	4.10%		4.10%		4.10%
Debt Instrument, Maturity Date			Sep. 19, 2023
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 50,000,000		$ 50,000,000
4.10% Senior Notes [Member] \| Us Dollar Amounts Member
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	50,000,000		50,000,000
4.10% Senior Notes [Member] \| Other Principal Trading Currencies [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 0		$ 0
3.84% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	3.84%		3.84%		3.84%
Debt Instrument, Maturity Date			Sep. 19, 2024
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 125,000,000		$ 125,000,000
3.84% Senior Notes [Member] \| Us Dollar Amounts Member
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	125,000,000		125,000,000
3.84% Senior Notes [Member] \| Other Principal Trading Currencies [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 0		$ 0
4.24% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	4.24%		4.24%		4.24%
Debt Instrument, Maturity Date			Jun. 25, 2025
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 125,000,000		$ 125,000,000
4.24% Senior Notes [Member] \| Us Dollar Amounts Member
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	125,000,000		125,000,000
4.24% Senior Notes [Member] \| Other Principal Trading Currencies [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 0		$ 0
1.47% EURO Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	1.47%		1.47%		1.47%
Debt Instrument, Maturity Date			Jun. 17, 2030
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 146,938,000		$ 146,938,000		€ 125,000
1.47% EURO Senior Notes [Member] \| Us Dollar Amounts Member
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	0		0
1.47% EURO Senior Notes [Member] \| Other Principal Trading Currencies [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 146,938,000		$ 146,938,000
Credit facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	0.875%		0.875%		0.875%
Debt Instrument, Maturity Date			Jun. 15, 2023
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Senior Notes	$ 1,100,000,000		$ 1,100,000,000
Line of Credit Facility, Fair Value of Amount Outstanding	493,241,000		$ 493,241,000
Debt Instrument, Covenant Description			Borrowings under the Credit Agreement bear interest at current market rates plus a margin based on the Company’s consolidated leverage ratio, which was set at LIBOR plus 87.5 basis points as of June 15, 2018. The Company must also pay facility fees that are tied to its leverage ratio. The Credit Agreement contains covenants that are the same as those contained in the prior Credit Agreement, with which the Company was in compliance as of June 30, 2018. The Company is required to maintain a ratio of funded debt to Consolidated EBITDA of 3.5 to1.0 or less and an interest coverage ration of 3.5 to 1.0 or greater. The Credit Agreement also places certain limitations on the Company, including limiting the ability to incur liens or indebtedness at a subsidiary level. In addition, the Credit Agreement has several events of default.
Write off of Deferred Debt Issuance Cost			$ 0.1
Debt Issuance Costs, Line of Credit Arrangements, Gross	2		2
Credit facility [Member] \| Us Dollar Amounts Member
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Line of Credit Facility, Fair Value of Amount Outstanding	443,776,000		443,776,000
Credit facility [Member] \| Other Principal Trading Currencies [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Line of Credit Facility, Fair Value of Amount Outstanding	49,465,000		49,465,000
Other local arrangements [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Other Borrowings	55,753,000		55,753,000
Other local arrangements [Member] \| Us Dollar Amounts Member
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Other Borrowings	14,000		14,000
Other local arrangements [Member] \| Other Principal Trading Currencies [Member]
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Other Borrowings	$ 55,739,000		$ 55,739,000
Swiss Pension Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	0.875%		0.875%		0.875%
Long-Term Debt, by Current and Noncurrent, and Short-Term Debt
Swiss Pension Loans (local currency)	$ 38.0		$ 38.0
Notes Payable, Related Parties	$ 39.6		$ 39.6