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Financial Derivative Instruments Narrative (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Derivative [Line Items] |  |  |  |
Percentage of actual consumption hedged |  | 79.00% |  |
Premiums paid for fuel derivative contracts |  | $ 135,000,000 | $ 136,000,000 | $ 154,000,000
Current Unrealized Net Loss in OCI |  | 36,000,000 |  |
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] | $ 138,000,000 | 283,000,000 |
Derivative Liability, Fair Value, Gross Liability | [1] | 14,000,000 | 57,000,000 |
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 May 2019 - 6.315% |  |  |  |
Derivative [Line Items] |  |  |  |
Interest rate stated in the debt agreement (in hundredths) |  | 6.315% |  |
Term Loan Agreement payable through May 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 November 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 May 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 November 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 |  | 3.40% |  |
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 |  | 3.58% |  |
Fuel derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Total collateral already posted aggregate fair value |  | $ 0 | 15,000,000 |
Interest rate derivatives | AirTran Airways |  |  |  |
Derivative [Line Items] |  |  |  |
Notional amount |  | $ 57,000,000 |  |
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) |  | 5.91% |  |
Designated as Hedging Instrument |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative Asset, Fair Value, Gross Asset | [1] | $ 138,000,000 | 248,000,000 |
Derivative Liability, Fair Value, Gross Liability | [1] | 14,000,000 | 20,000,000 |
Other Noncurrent Liabilities | Interest rate derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative Liability, Fair Value, Gross Liability |  | 14,000,000 |  |
Other Noncurrent Liabilities | Designated as Hedging Instrument | Interest rate derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative Liability, Fair Value, Gross Liability | [1] | 12,000,000 | 20,000,000 |
Other Assets | Designated as Hedging Instrument | Fuel derivatives |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative Asset, Fair Value, Gross Asset | [1] | $ 95,000,000 | $ 136,000,000 |
2019 |  |  |  |
Derivative [Line Items] |  |  |  |
Percent of fuel consumption hedged |  | 70.00% |  |
[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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