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Long-Term Debt (IKE Zone Bonds) (Details) - Senior Notes [Member] - USD ($) $ in Millions | 1 Months Ended |  |  |
--- | --- | --- | --- | ---
Nov. 30, 2020 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2010
6.5% 2035 IKE Zone Senior Notes [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Long-term Debt, Gross |  | $ 0 | $ 65 | $ 65
Extinguishment of Debt, Amount | $ 65 |  |  |
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed | 100.00% |  |  |
6 1/2% GO Zone Senior Notes Due 2035 [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Long-term Debt, Gross |  | $ 0 | $ 89 | $ 89
Extinguishment of Debt, Amount | $ 89 |  |  |
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed | 100.00% |  |  |

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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Percentage of principal amount of debt redeemed. + References No definition available. + Details
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