Derivative Financial Instruments Derivative Financial Instruments (Schedule of Cross Currency Swaps) (Details) € in Millions, $ in Millions	Mar. 31, 2015 USD ($)	Mar. 31, 2015 EUR (€)	Dec. 31, 2014 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Value			$ 500
Swap Derivative 4 Point 27 Percent Maturing September 11, 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Value	$ 250
Swap Derivative 2 Point 63 Percent Maturing September 11, 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Value | €		€ 193
Swap Derivative 3 Point 62 Percent Maturing April 17, 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Value | €		€ 162
Swap Derivative 2 Point 77 Percent Maturing April 17, 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Value	225
Cross-currency swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Cash Received on Hedge	$ 88