Stock-Based Awards and Other Equity Instruments - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for new stock-based awards, shares	13,000,000
Stock-based compensation	$ 149,350	$ 242,417	$ 178,068
Market value of shares vested in period	65,000	57,000	60,000
Stock-based compensation tax benefit	38,000	56,000	45,000
Cash received from stock-based award exercises	213,000	128,000
Income tax benefit associated with employees exercise of stock-based awards	100,000	$ 76,000	$ 130,000
Unrecognized stock-based compensation expense	$ 410,000
Unrecognized stock-based compensation expense expected recognition period	2 years 7 months 6 days
Employee Stock Purchase Plan 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock purchase price as percentage of fair market value	85.00%
Eligible employees contribution of base compensation	10.00%
Employee stock purchase plan, shares purchased	141,000	139,000	95,000
Employee stock ownership plan, average purchase price of shares purchased	$ 112.31	$ 95.63	$ 93.30
Shares of our common stock reserved for issuance	1,000,000
Former Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation recovered due to forfeiture of awards	$ 41,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price, as of year end (in dollars per share)	$ 119.77
Total intrinsic value of stock options exercised, value	$ 249,000	$ 181,000	$ 314,000
Stock options granted during the period	3,618,000	5,670,000	7,572,000
Vesting period	4 years
Weighted average exercise price of shares issued (in dollars per share)	$ 62.67	$ 47.57	$ 34.57
Stock Options | Chairman And Senior Executive
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued upon exercise of options			1,900,000
Shares withheld to cover exercise price			500,000
Weighted average exercise price of shares issued (in dollars per share)			$ 30.38
Shares withheld to pay for tax obligations			800,000
Shares issued net of forfeitures			600,000
RSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
RSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
trivago
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock based expense due to call of options previously exercised		$ 49,000