Debt Debt Parathenticals (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 250,000
6.30% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.30%	6.30%
Debt Instrument, Face Amount	100,000	100,000
Debt Instrument, Maturity Date	Jun. 25, 2015
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	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