Inventory (Inventory) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Land held for VOI development	$ 4	$ 146
VOI construction in process	25	59
Inventory sold subject to conditional repurchase	43	163
Completed VOI inventory	841	667
Estimated VOI recoveries	279	256
Destination network vacation credits and other	57	54
Total inventory	1,249	1,345
Less: Current portion	340	310
Non-current inventory	$ 909	$ 1,035