Commitments and Contingencies (Details) - USD ($) $ in Millions		3 Months Ended
		Jun. 30, 2017	Dec. 31, 2010	Dec. 31, 2016
Airport Project [Line Items]
Assets constructed for others		$ 1,404		$ 1,220
Assets constructed for others, net		1,327		1,156
Construction obligation		1,258		1,078
Fort Lauderdale-Hollywood International Airport
Airport Project [Line Items]
Total Expected Cost Of Airport Project		333
Assets constructed for others	[1]	229		132
Assets constructed for others, net	[1],[2]	229		132
Construction obligation	[1]	229		132
Los Angeles World Airport
Airport Project [Line Items]
Total Expected Cost Of Airport Project		526
Assets constructed for others	[1]	397		344
Assets constructed for others, net	[1],[2]	386		336
Construction obligation	[1]	397		344
Dallas Love Field Terminal
Airport Project [Line Items]
Assets constructed for others		538		538
Assets constructed for others, net	[2]	478		486
Construction obligation		518		522
Municipal bonds issued			$ 456
Municipal bonds principal remaining		432
Dallas Love Field Parking Garage
Airport Project [Line Items]
Assets constructed for others	[1]	114		80
Assets constructed for others, net	[1],[2]	114		80
Construction obligation	[1]	114		80
Houston Hobby Airport
Airport Project [Line Items]
Assets constructed for others	[3]	126		126
Assets constructed for others, net	[2],[3]	120		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").