Commitments and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2012	Dec. 31, 2010	Sep. 30, 2015	Dec. 31, 2014
Airport Project [Line Items]
Assets constructed for others			$ 823	$ 621
Construction obligation			684	$ 554
Fort Lauderdale-Hollywood International Airport
Airport Project [Line Items]
Total Expected Cost Of Airport Project			295
Assets constructed for others			17
HOU
Airport Project [Line Items]
Total Expected Cost Of Airport Project			156
Assets constructed for others			128
Los Angeles World Airport
Airport Project [Line Items]
Total Expected Cost Of Airport Project			526
Assets constructed for others			151
Construction obligation			151
DAL
Airport Project [Line Items]
Assets constructed for others			527
Municipal bonds issued	$ 146	$ 310
Construction obligation			$ 516