Debt Debt Parathenticals (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
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%
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%
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%
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%
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%
Debt Instrument, Face Amount	$ 0
Debt Instrument, Maturity Date	Jun. 17, 2030
Amortized Issuance Costs Period	15 years