Debt Debt Parathenticals (Details) € in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2015 EUR (€)
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 250,000
4.24% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.24%	4.24%
Debt Instrument, Face Amount	$ 125,000
Debt Instrument, Maturity Date	Jun. 25, 2025
3.67% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.67%	3.67%
Debt Instrument, Face Amount	$ 50,000
Debt Instrument, Maturity Date	Dec. 17, 2022
4.10% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.10%	4.10%
Debt Instrument, Face Amount	$ 50,000
Debt Instrument, Maturity Date	Sep. 19, 2023
3.84% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.84%	3.84%
Debt Instrument, Face Amount	$ 125,000
Debt Instrument, Maturity Date	Sep. 19, 2024
1.47% EURO Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.47%	1.47%
Debt Instrument, Face Amount | €		€ 125,000
Debt Instrument, Maturity Date	Jun. 17, 2030