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Commitments and Contingencies (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Sep. 30, 2017 | Dec. 31, 2010 | Dec. 31, 2016
Airport Project [Line Items] |  |  |  |
Assets constructed for others |  | $ 1,460 |  | $ 1,220
Assets constructed for others, net |  | 1,373 |  | 1,156
Construction obligation |  | 1,311 |  | 1,078
Fort Lauderdale-Hollywood International Airport |  |  |  |
Airport Project [Line Items] |  |  |  |
Total Expected Cost Of Airport Project |  | 333 |  |
Assets constructed for others | [1] | 245 |  | 132
Assets constructed for others, net | [1],[2] | 244 |  | 132
Construction obligation | [1] | 245 |  | 132
Los Angeles World Airport Terminal 1 |  |  |  |
Airport Project [Line Items] |  |  |  |
Total Expected Cost Of Airport Project |  | 526 |  |
Total Expected Cost Of Airport Project Nonproprietary |  | 510 |  |
Remaining guaranteed obligation |  | 299 |  |
Assets constructed for others | [1] | 417 |  | 344
Assets constructed for others, net | [1],[2] | 404 |  | 336
Construction obligation | [1] | 417 |  | 344
Los Angeles World Airport Terminal 1.5 |  |  |  |
Airport Project [Line Items] |  |  |  |
Total Expected Cost Of Airport Project |  | 479 |  |
Remaining guaranteed obligation |  | 0 |  |
Dallas Love Field Terminal |  |  |  |
Airport Project [Line Items] |  |  |  |
Assets constructed for others |  | 540 |  | 538
Assets constructed for others, net | [2] | 474 |  | 486
Construction obligation |  | 517 |  | 522
Municipal bonds issued |  |  | $ 456 |
Municipal bonds principal remaining |  | 432 |  |
Dallas Love Field Parking Garage |  |  |  |
Airport Project [Line Items] |  |  |  |
Assets constructed for others | [1] | 132 |  | 80
Assets constructed for others, net | [1],[2] | 132 |  | 80
Construction obligation | [1] | 132 |  | 80
Houston Hobby Airport |  |  |  |
Airport Project [Line Items] |  |  |  |
Assets constructed for others | [3] | 126 |  | 126
Assets constructed for others, net | [2],[3] | 119 |  | 122
Construction obligation | [3] | $ 0 |  | $ 0
[1] | Projects still in progress.
[2] | Net of accumulated depreciation.
[3] | Project completed in 2015 at Houston William P. Hobby Airport ("HOU").

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- Details
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