Redeemable Non-controlling Interests - Additional Information (Details) - USD ($) $ in Millions |
12 Months Ended | |||
|---|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2013 |
Aug. 31, 2018 |
Dec. 16, 2016 |
|
| Redeemable Noncontrolling Interest [Line Items] | ||||
| Proceeds related to trivago IPO, net of fees and expenses | $ 210 | |||
| Ownership interest percentage | 25.00% | |||
| trivago | ||||
| Redeemable Noncontrolling Interest [Line Items] | ||||
| Percentage of remaining minority ownership interest that may be acquired | 50.00% | |||
| Percentage of remaining minority ownership interest to be acquired | 100.00% | |||
| trivago | ||||
| Redeemable Noncontrolling Interest [Line Items] | ||||
| Ownership interest percentage | 59.70% | 63.50% | ||
| Voting interest percentage | 64.70% | |||