Long-Term Debt (Debt Tender Offers and Redemption) (Details) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | |||||
---|---|---|---|---|---|---|---|
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
Extinguishment of Debt [Line Items] | |||||||
Premiums and fees | $ 809 | $ 226 | |||||
Write-off of unamortized debt discounts and debt issuance costs | 14 | 2 | |||||
Loss on early extinguishment of debt | $ 0 | $ 823 | $ 0 | $ 0 | $ 0 | 823 | 228 |
Senior Notes [Member] | |||||||
Extinguishment of Debt [Line Items] | |||||||
Notes Purchased | 933 | 793 | |||||
9.95% Notes due 2038 [Member] | Senior Notes [Member] | |||||||
Extinguishment of Debt [Line Items] | |||||||
Notes Purchased | 441 | 0 | |||||
Stated interest rate | 9.95% | ||||||
10.20% Note due 2039 [Member] | Senior Notes [Member] | |||||||
Extinguishment of Debt [Line Items] | |||||||
Notes Purchased | 492 | 0 | |||||
Stated interest rate | 10.20% | ||||||
9.70% Notes due 2018 [Member] | Senior Notes [Member] | |||||||
Extinguishment of Debt [Line Items] | |||||||
Notes Purchased | $ 0 | $ 793 | |||||
Stated interest rate | 9.70% | 9.70% |