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Financial Derivative Instruments Narrative (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Derivative [Line Items] |  |  |  |
Percent of fuel consumption hedged |  | 63.00% |  |
Premiums paid for fuel derivative contracts |  | $ 135,000,000 | $ 153,000,000 | $ 124,000,000
Current Unrealized Net Loss in OCI |  | 11,000,000 |  |
Proceeds from termination of interest rate derivative instrument |  | 0 | 0 | $ 12,000,000
Maximum sum of derivatives of counterparty to be included in other (less than $10 million) |  | $ 5,000,000 |  |
Cash collateral provided as a percentage of derivative contract value (in hundredths) |  | 100.00% |  |
Derivative Asset, Fair Value, Gross Asset | [1] | $ 283,000,000 | 444,000,000 |
Derivative Liability, Fair Value, Gross Liability | [1] | 57,000,000 | 805,000,000 |
Term Loan Agreement payable through 2020 - 5.223% |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 600,000,000 |  |
Interest rate stated in the debt agreement (in hundredths) |  | 5.223% |  |
Term Loan Agreement payable through 2019 - 6.315% |  |  |  |
Derivative [Line Items] |  |  |  |
Interest rate stated in the debt agreement (in hundredths) |  | 6.315% |  |
Term Loan Agreement payable through 2019 - 6.315% | Maximum |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 332,000,000 |  |
Unsecured Senior Notes Due 2027 |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 300,000,000 |  |
Interest rate stated in the debt agreement (in hundredths) |  | 3.45% |  |
2.75% Unsecured Senior Notes Due 2019 |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 300,000,000 |  |
Interest rate stated in the debt agreement (in hundredths) |  | 2.75% |  |
2.65% Notes due 2020 |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 500,000,000 |  |
Interest rate stated in the debt agreement (in hundredths) |  | 2.65% |  |
Notes Payable to Banks | Term Loan Agreement payable through 2020 - 5.223% |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 600,000,000 |  |
Interest rate stated in the debt agreement (in hundredths) |  | 5.223% |  |
Notes Payable to Banks | Term Loan Agreement payable through 2019 - 6.315% |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 332,000,000 |  |
Interest rate stated in the debt agreement (in hundredths) |  | 6.315% |  |
Unsecured Debt | 2.75% Unsecured Senior Notes Due 2019 |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 300,000,000 |  |
Interest rate stated in the debt agreement (in hundredths) |  | 2.75% |  |
Average Floating Rate |  | 2.29% |  |
Unsecured Debt | 2.65% Notes due 2020 |  |  |  |
Derivative [Line Items] |  |  |  |
Face amount of debt |  | $ 500,000,000 |  |
Interest rate stated in the debt agreement (in hundredths) |  | 2.65% |  |
Average Floating Rate |  | 2.47% |  |
Fuel derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Total collateral already posted aggregate fair value |  | $ (15,000,000) | 301,000,000 |
Interest rate derivatives | AirTran Airways |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount |  | $ 124,000,000 |  |
Interest rate derivatives | AirTran Airways | Minimum |  |  |  |
Derivative [Line Items] |  |  |  |
Interest rate stated in the debt agreement (in hundredths) |  | 4.35% |  |
Interest rate derivatives | AirTran Airways | Maximum |  |  |  |
Derivative [Line Items] |  |  |  |
Interest rate stated in the debt agreement (in hundredths) |  | 6.435% |  |
Designated as Hedging Instrument |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative Asset, Fair Value, Gross Asset | [1] | $ 248,000,000 | 137,000,000 |
Derivative Liability, Fair Value, Gross Liability | [1] | 20,000,000 | 491,000,000 |
Other Noncurrent Liabilities | Interest rate derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative Liability, Fair Value, Gross Liability |  | 22,000,000 |  |
Other Noncurrent Liabilities | Designated as Hedging Instrument | Interest rate derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative Liability, Fair Value, Gross Liability | [1] | 20,000,000 | 35,000,000 |
Other Assets | Designated as Hedging Instrument | Fuel derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative Asset, Fair Value, Gross Asset | [1] | $ 136,000,000 | $ 126,000,000 |
2018 |  |  |  |
Derivative [Line Items] |  |  |  |
Percent of fuel consumption hedged |  | 78.00% |  |
[1] | Represents the position of each trade before consideration of offsetting positions with each counterparty and does not include the impact of cash collateral deposits provided to or received from counterparties. See discussion of credit risk and collateral following in this Note.

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Represents percentage of cash collateral provided on the fair value of fuel derivative contracts when credit rating is non-investment grade. + References No definition available. + Details
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- Definition Proceeds from the termination of derivative instruments that had been previously used either to swap periodic payments that were fixed at the outset of the swap contract with variable payments based on the market interest rate, or were variable at the outset of the swap contract with fixed payments based on the market interest rate, over a specified period. + References No definition available. + Details
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- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4D -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719 + Details
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