Debt and Credit Arrangements Convertible Debt (Details) (USD $)	12 Months Ended			1 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 4.75% Convertible Senior Notes due 2023	Mar. 15, 2013 4.75% Convertible Senior Notes due 2023	Mar. 31, 2012 4.25% Convertible Senior Notes due 2023	Mar. 15, 2012 4.25% Convertible Senior Notes due 2023
Debt Conversion [Line Items]
Extinguishment of Debt, Amount		$ 200,000,000		$ 400,000,000
Debt Instrument, Convertible, Conversion Price					$ 82,461,200
Debt Conversion, Converted Instrument, Amount				400,000
Debt Instrument, Convertible, Convertible Shares Eliminated due to Retirement					33,000,000
Debt Instrument, Convertible, Conversion Ratio		84.3402
RedemptionOfConvertibleNotesforCash			$ 199,997,000		$ 399,600,000
Debt Conversion, Converted Instrument, Shares Issued				30,000
Stock Issued During Period, Shares, Conversion of Convertible Securities	17,300,000	16,900,000