Debt And Interest Expense Debt and Interest Expense (Senior Notes) (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended
	Apr. 30, 2013 Rate	Dec. 31, 2013	Apr. 16, 2013 Rate	Dec. 31, 2012	Aug. 31, 2007 Rate	Aug. 15, 2007 Rate
Debt Disclosure [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity		$ 200,000,000
Debt Instrument, Offering Date	Apr. 16, 2013
Debt Instrument, Face Amount		1,250,000,000	750,000,000	1,250,000,000		1,250,000,000
Debt Instrument, Interest Rate, Stated Percentage			4.625%		3.25%	3.25%
Debt Instrument, Maturity Date	May 01, 2023
Issue price of debt instrument as percentage of face amount			100.00%
Repayments of Lines of Credit		100,000,000
issuance cost on senior note		$ 12,000,000
Maximum percentage of Senior Notes redemmable on or before 2018	35.00%
Redemption Price Percentage For Redemption On Before 2018	104.625%
Redemption Price Of Senior Notes If Change Of Control	101.00%
Debt Instrument, Term Length		10 years