Fair Value of Financial Instruments, Non-Recurring Basis (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Long term debt - 2016 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Carrying Value	$ 500		$ 500
Long-term Debt, Fair Value	514		519
Long term debt - 2018 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Carrying Value	724		724
Long-term Debt, Fair Value	843		856
Long term debt - 2019 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Carrying Value	249	[1]	248	[1]
Long-term Debt, Fair Value	254		252
Long term debt - 2020 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Carrying Value	243	[1]	241	[1]
Long-term Debt, Fair Value	243		236
Long term debt - 2021 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Carrying Value	246	[1]	241	[1]
Long-term Debt, Fair Value	254		241
Long-term debt - 2022 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Carrying Value	256	[1]	247	[1]
Long-term Debt, Fair Value	240		226
Long term debt - 2038 Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Carrying Value	264	[1]	252	[1]
Long-term Debt, Fair Value	$ 352		$ 317

[1] The carrying amount includes the unamortized discounts on the issuance of debt and adjustments related to the change in the fair value of interest rate swaps designated as fair value hedges on the 2019, 2020, 2021, 2022 and 2038 Notes. Refer to Note 6 for additional information regarding derivatives.