Revenue Recognition - Reconciliation of Disaggregated Revenue to Segment Revenue (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Disaggregation Of Revenue [Line Items]
Total Revenue	$ 378
Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue	299	[1]
Non-Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue	79	[1]
Click-Based Advertising and Transaction Revenue | Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue	189
Display-Based Advertising and Subscription Revenue | Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue	71
Other Hotel Revenue | Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue	$ 39

[1] Our revenue is recognized primarily at a point in time for both our Hotel and Non-Hotel segments.