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Fair Value Measurements - Measured on Recurring Basis (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Jun. 30, 2015 | Dec. 31, 2012 | Dec. 31, 2014
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset | [1] | $ 627 |  |  | $ 1,360 |
Fuel derivatives: |  |  |  |  |  |
Derivative Liability, Fair Value, Gross Liability | [1] | (1,708) |  |  | (2,409) |
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount |  | 0 |  |  | 0 |
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount |  | 0 |  |  | 0 |
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount |  | 0 |  |  | 0 |
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount |  | 0 |  |  | 0 |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net |  | 0 |  | $ 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net |  | 0 |  | $ 0 |  |
Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Assets |  |  |  |  |  |
Treasury bills |  | 1,150 |  |  | 1,450 |
Interest rate derivatives |  | 1 |  |  | 13 |
Other available for sale securities |  | 67 |  |  | 68 |
Total assets |  | 3,853 |  |  | 4,443 |
Liabilities |  |  |  |  |  |
Interest rate derivatives |  | (54) |  |  | (61) |
Total Liabilities |  | (1,708) |  |  | (2,409) |
Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Assets |  |  |  |  |  |
Treasury bills |  | 1,150 |  |  | 1,450 |
Interest rate derivatives |  | 0 |  |  | 0 |
Other available for sale securities |  | 67 |  |  | 63 |
Total assets |  | 2,782 |  |  | 2,623 |
Liabilities |  |  |  |  |  |
Interest rate derivatives |  | 0 |  |  | 0 |
Total Liabilities |  | 0 |  |  | 0 |
Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Assets |  |  |  |  |  |
Treasury bills |  | 0 |  |  | 0 |
Interest rate derivatives |  | 1 |  |  | 13 |
Other available for sale securities |  | 0 |  |  | 0 |
Total assets |  | 712 |  |  | 896 |
Liabilities |  |  |  |  |  |
Interest rate derivatives |  | (54) |  |  | (61) |
Total Liabilities |  | (321) |  |  | (426) |
Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Assets |  |  |  |  |  |
Treasury bills |  | 0 |  |  | 0 |
Interest rate derivatives |  | 0 |  |  | 0 |
Other available for sale securities |  | 0 |  |  | 5 |
Total assets |  | 359 |  |  | 924 |
Liabilities |  |  |  |  |  |
Interest rate derivatives |  | 0 |  |  | 0 |
Total Liabilities |  | (1,387) |  |  | (1,983) |
Cash Equivalents | Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 1,565 | [2] |  | 1,110 | [3]
Cash Equivalents | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 1,565 | [2] |  | 1,110 | [3]
Cash Equivalents | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 0 | [2] |  | 0 | [3]
Cash Equivalents | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 0 | [2] |  | 0 | [3]
Commercial paper | Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 125 |  |  | 70 |
Commercial paper | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 0 |  |  | 0 |
Commercial paper | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 125 |  |  | 70 |
Commercial paper | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 0 |  |  | 0 |
Certificates of deposit | Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 8 |  |  | 4 |
Certificates of deposit | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 0 |  |  | 0 |
Certificates of deposit | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 8 |  |  | 4 |
Certificates of deposit | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 0 |  |  | 0 |
Eurodollar time deposits | Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 74 |  |  | 98 |
Eurodollar time deposits | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 0 |  |  | 0 |
Eurodollar time deposits | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 74 |  |  | 98 |
Eurodollar time deposits | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Assets |  |  |  |  |  |
Cash equivalents |  | 0 |  |  | 0 |
Certificates of deposit | Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Assets |  |  |  |  |  |
Investments |  | 210 |  |  | 256 |
Certificates of deposit | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Assets |  |  |  |  |  |
Investments |  | 0 |  |  | 0 |
Certificates of deposit | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Assets |  |  |  |  |  |
Investments |  | 210 |  |  | 256 |
Certificates of deposit | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Assets |  |  |  |  |  |
Investments |  | 0 |  |  | 0 |
Auction rate securities | Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Assets |  |  |  |  |  |
Investments |  | 27 | [4] |  | 27 | [5]
Auction rate securities | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Assets |  |  |  |  |  |
Investments |  | 0 | [4] |  | 0 | [5]
Auction rate securities | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Assets |  |  |  |  |  |
Investments |  | 0 | [4] |  | 0 | [5]
Auction rate securities | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Assets |  |  |  |  |  |
Investments |  | 27 | [4] |  | 27 | [5]
Swap | Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 294 | [6] |  | 455 | [7]
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | (267) | [6] |  | (365) | [7]
Swap | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 0 | [6] |  | 0 | [7]
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | 0 | [6] |  | 0 | [7]
Swap | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 294 | [6] |  | 455 | [7]
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | (267) | [6] |  | (365) | [7]
Swap | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 0 | [6] |  | 0 | [7]
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | 0 | [6] |  | 0 | [7]
Options Held | Fair Value, Measurements, Recurring | Period end date |  |  |  |  |  |
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 332 | [6] |  | 892 | [7]
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | (1,387) | [6] |  | (1,983) | [7]
Options Held | Fair Value, Measurements, Recurring | Quoted prices in active markets for identical assets (Level 1) |  |  |  |  |  |
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 0 | [6] |  | 0 | [7]
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | 0 | [6] |  | 0 | [7]
Options Held | Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) |  |  |  |  |  |
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 0 | [6] |  | 0 | [7]
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | 0 | [6] |  | 0 | [7]
Options Held | Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) |  |  |  |  |  |
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Asset |  | 332 | [6] |  | 892 | [7]
Fuel derivatives: |  |  |  |  |  |
Derivative Asset, Fair Value, Gross Liability |  | $ (1,387) | [6] |  | $ (1,983) | [7]
[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.
[2] | Cash equivalents are primarily composed of money market investments.
[3] | Cash equivalents are primarily composed of money market investments.
[4] | Noncurrent investments are included in Other assets in the unaudited Condensed Consolidated Balance Sheet.
[5] | Noncurrent investments are included in Other assets in the unaudited Condensed Consolidated Balance Sheet.
[6] | In the unaudited Condensed Consolidated Balance Sheet amounts are presented as a net liability.
[7] | In the unaudited Condensed Consolidated Balance Sheet amounts are presented as a net liability.

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