Debt (Textuals) (Details) € in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015 EUR (€)	Dec. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Losses on Extinguishment of Debt	$ 0	$ 0	$ 200,000
Debt issuance cost		1,200,000	1,400,000
Long-term debt		335,500,000			$ 298,200,000
Long-term debt, excluding current portion		308,300,000			228,900,000
Interest expense	$ 15,600,000	18,100,000	$ 18,600,000
Aggregate annual maturities of long-term debt [Abstract]
2016					69,300,000
2017					2,200,000
2018					32,600,000
2020					27,100,000
Thereafter					$ 168,000,000
Senior A Notes Due 2022 [Member]
Line of Credit Facility [Line Items]
Debt instrument, maturity date	Jul. 05, 2022
Debt instrument, stated interest rate				3.67%	3.67%
Senior B Notes Due 2024 [Member]
Line of Credit Facility [Line Items]
Debt instrument, maturity date	Jul. 05, 2024
Debt instrument, stated interest rate				3.82%	3.82%
Senior C Notes Due 2027 [Member]
Line of Credit Facility [Line Items]
Debt instrument, maturity date	Jul. 05, 2027
Debt instrument, stated interest rate				4.02%	4.02%
Series B Floating Rate Notes Due 2015 [Member]
Line of Credit Facility [Line Items]
Long-term debt		25,000,000
Euro Note B Due 2016 [Member]
Line of Credit Facility [Line Items]
Long-term debt		74,300,000
Term of debt	10 years
Debt Instrument, face amount | €				€ 61.1
Debt instrument, maturity date	Feb. 27, 2016
Debt instrument, stated interest rate				4.38%	4.38%
Revolving Credit Facility Due 2017 [Member]
Line of Credit Facility [Line Items]
Line of credit, noncurrent		29,700,000			$ 0
Variable rate basis	LIBOR
Term Loan Due 2018 [Member]
Line of Credit Facility [Line Items]
Debt issuance cost	$ 100,000	200,000
Long-term debt		39,000,000			37,000,000
Long-term Debt, Current Maturities					2,400,000
Variable rate basis	LIBOR
Basis spread on variable interest rate	1.50%
Long-term Debt, Gross					37,100,000
Debt Instrument, face amount					$ 42,800,000
Debt Instrument, Term	5 years
Debt instrument, maturity date	Jan. 31, 2018
Debt instrument, stated interest rate				1.74%	1.74%
Revolving credit facility, due 2020 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, current borrowing capacity					$ 300,000,000.0
Line of Credit Facility Additional Borrowing Capacity					100,000,000
Credit facility is available for swing-line loans					30,000,000.0
Credit available for the issuance of letters of credit					30,000,000.0
Debt issuance cost	$ 1,600,000
Line of credit, noncurrent		0			27,100,000
Line of Credit Facility, unused commitment level					$ 269,900,000
Debt instrument, stated interest rate				1.71%	1.71%
Senior Notes [Member]
Line of Credit Facility [Line Items]
Debt issuance cost	$ 900,000	1,000,000
Debt Instrument, face amount					$ 168,000,000
Weighted average of the coupon interest rate				3.87%	3.87%
Annual effective interest rate				4.16%	4.16%
Senior Notes [Member] | Senior A Notes Due 2022 [Member]
Line of Credit Facility [Line Items]
Long-term debt		41,800,000			$ 41,800,000
Debt Instrument, face amount					$ 42,000,000
Debt instrument, stated interest rate				3.67%	3.67%
Senior Notes [Member] | Senior B Notes Due 2024 [Member]
Line of Credit Facility [Line Items]
Long-term debt		52,700,000			$ 52,700,000
Debt Instrument, face amount					$ 53,000,000
Debt instrument, stated interest rate				3.82%	3.82%
Senior Notes [Member] | Senior C Notes Due 2027 [Member]
Line of Credit Facility [Line Items]
Long-term debt		$ 72,500,000			$ 72,600,000
Debt Instrument, face amount					$ 73,000,000
Debt instrument, stated interest rate				4.02%	4.02%
Letter of Credit [Member] | Revolving credit facility, due 2020 [Member]
Line of Credit Facility [Line Items]
Outstanding amount					$ 3,000,000