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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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Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Total cash, current and noncurrent, that is already posted, at the end of the reporting period, as collateral for derivative instruments.

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