Schedule II - Condensed Financial Information, Short-term and Long-term Debt (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Notes due 2016 2.75% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2016 2.75% Interest [Member] Uncollateralized Debt [Member]	Nov. 10, 2011 Notes due 2016 2.75% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2017 5.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2017 5.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2018 6.35% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2018 6.35% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2019 8.5% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2019 8.5% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2020 4.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2020 4.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2020 5.125% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2020 5.125% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes Due 2021 4.5% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes Due 2021 4.5% Interest [Member] Uncollateralized Debt [Member]	Mar. 31, 2011 Notes Due 2021 4.5% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2022 4% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2022 4% Interest [Member] Uncollateralized Debt [Member]	Nov. 10, 2011 Notes due 2022 4% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2023 7.65% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2023 7.65% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2023 8.3% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2023 8.3% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Debentures due 2027 7.875% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Debentures due 2027 7.875% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Step Down Notes Due 2033 8.3% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Step Down Notes Due 2033 8.3% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2036 6.15% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2036 6.15% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes Due 2041 5.875% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes Due 2041 5.875% Interest [Member] Uncollateralized Debt [Member]	Mar. 31, 2011 Notes Due 2041 5.875% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Notes due 2042 5.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Notes due 2042 5.375% Interest [Member] Uncollateralized Debt [Member]	Nov. 10, 2011 Notes due 2042 5.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member]	Dec. 31, 2012 Parent Company [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2016 2.75% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2016 2.75% Interest [Member] Uncollateralized Debt [Member]	Nov. 10, 2011 Parent Company [Member] Notes due 2016 2.75% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2017 5.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2017 5.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2018 6.35% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2018 6.35% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2019 8.5% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2019 8.5% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2020 4.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2020 4.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2020 5.125% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2020 5.125% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes Due 2021 4.5% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes Due 2021 4.5% Interest [Member] Uncollateralized Debt [Member]	Mar. 31, 2011 Parent Company [Member] Notes Due 2021 4.5% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2022 4% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2022 4% Interest [Member] Uncollateralized Debt [Member]	Nov. 10, 2011 Parent Company [Member] Notes due 2022 4% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2023 7.65% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2023 7.65% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2023 8.3% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2023 8.3% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Debentures due 2027 7.875% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Debentures due 2027 7.875% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Step Down Notes Due 2033 8.3% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Step Down Notes Due 2033 8.3% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2036 6.15% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2036 6.15% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes Due 2041 5.875% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes Due 2041 5.875% Interest [Member] Uncollateralized Debt [Member]	Mar. 31, 2011 Parent Company [Member] Notes Due 2041 5.875% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2013 Parent Company [Member] Notes due 2042 5.375% Interest [Member] Uncollateralized Debt [Member]	Dec. 31, 2012 Parent Company [Member] Notes due 2042 5.375% Interest [Member] Uncollateralized Debt [Member]	Nov. 10, 2011 Parent Company [Member] Notes due 2042 5.375% Interest [Member] Uncollateralized Debt [Member]
Debt Instrument [Line Items]
Commercial paper	$ 100	$ 200																																				$ 100	$ 200
Total short-term debt	233	201																																				100	200
Long-term debt	$ 5,014	$ 4,986	$ 600	$ 600	$ 600	$ 250	$ 250	$ 131	$ 131	$ 251	$ 251	$ 249	$ 249	$ 299	$ 299	$ 299	$ 299	$ 298	$ 744	$ 743	$ 743	$ 100	$ 100	$ 17	$ 17	$ 300	$ 300	$ 83	$ 83	$ 500	$ 500	$ 298	$ 298	$ 298	$ 750	$ 750	$ 750	$ 4,871	$ 4,870	$ 600	$ 600	$ 600	$ 250	$ 250	$ 131	$ 131	$ 251	$ 251	$ 249	$ 249	$ 299	$ 299	$ 299	$ 299	$ 298	$ 744	$ 743	$ 743	$ 100	$ 100	$ 17	$ 17	$ 300	$ 300	$ 83	$ 83	$ 500	$ 500	$ 298	$ 298	$ 298	$ 750	$ 750	$ 750