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Commitments and Contingencies - Airport Projects (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2010 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Airport Project [Line Items] |  |  |  |  |
Assets constructed for others |  |  | $ 1,543 | $ 1,220 |
AssetsConstructedForOthersNet | [1] |  | 1,448 | 1,156 |
Depreciation and amortization |  |  | 1,218 | 1,221 | $ 1,015
Construction obligation | [2] |  | 1,390 | 1,078 |
Los Angeles World Airport Terminal 1 |  |  |  |  |
Airport Project [Line Items] |  |  |  |  |
Expected total airport modernization project cost |  |  | 526 |  |
Contractual Obligation |  |  | 230 |  |
Expected Total Cost Of Airport Project Nonproprietary |  |  | 510 |  |
Assets constructed for others | [3] |  | 433 | 344 |
AssetsConstructedForOthersNet | [1],[3] |  | 417 | 336 |
Construction obligation | [2],[3] |  | 433 | 344 |
Los Angeles World Airport Terminal 1.5 |  |  |  |  |
Airport Project [Line Items] |  |  |  |  |
Expected total airport modernization project cost |  |  | 479 |  |
Contractual Obligation |  |  | 36 |  |
Assets constructed for others | [3] |  | 31 | 0 |
AssetsConstructedForOthersNet | [1],[3] |  | 31 | 0 |
Construction obligation | [2],[3] |  | 31 | 0 |
FLL |  |  |  |  |
Airport Project [Line Items] |  |  |  |  |
Expected total airport modernization project cost |  |  | 333 |  |
Assets constructed for others | [3] |  | 258 | 132 |
AssetsConstructedForOthersNet | [1],[3] |  | 256 | 132 |
Construction obligation | [2],[3] |  | 258 | 132 |
DAL |  |  |  |  |
Airport Project [Line Items] |  |  |  |  |
Municipal bonds issued |  | $ 456 |  |  |
Municipal Bonds Principal Remaining |  |  | 424 |  |
Assets constructed for others | [3] |  | 543 | 538 |
AssetsConstructedForOthersNet | [1],[3] |  | 474 | 486 |
Construction obligation | [2],[3] |  | 516 | 522 |
HOU |  |  |  |  |
Airport Project [Line Items] |  |  |  |  |
Assets constructed for others | [4] |  | 126 | 126 |
AssetsConstructedForOthersNet | [1],[4] |  | 118 | 122 |
Construction obligation | [2],[4] |  | 0 | 0 |
DALGarage |  |  |  |  |
Airport Project [Line Items] |  |  |  |  |
Assets constructed for others | [3] |  | 152 | 80 |
AssetsConstructedForOthersNet | [1],[3] |  | 152 | 80 |
Construction obligation | [2],[3] |  | $ 152 | $ 80 |
[1] | Net of accumulated depreciation.
[2] | Construction obligation will be reduced through future facility rent payments. These future payments are not fixed per the lease agreement, but are variable and fluctuate based on various market and other factors outside the control of the Company.
[3] | Projects still in progress.
[4] | Project completed in 2015 at Houston William P. Hobby Airport ("HOU").

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