Tripadvisor (TRIP) 10-Q 7 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 01, 2018
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Registrant Name	TripAdvisor, Inc.
Trading Symbol	TRIP
Entity Central Index Key	1,526,520
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Common Stock, Unclassified
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		124,866,383
Class B Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		12,799,999

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue (Note 3)		$ 458	$ 439	$ 1,269	$ 1,235
Costs and expenses:
Cost of revenue	[1]	23	20	67	56
Selling and marketing	[2]	206	247	621	683
Technology and content	[2]	72	61	207	184
General and administrative	[2]	40	42	129	115
Depreciation		20	19	61	57
Amortization of intangible assets		8	8	24	25
Total costs and expenses:		369	397	1,109	1,120
Operating income		89	42	160	115
Other income (expense):
Interest expense		(4)	(4)	(10)	(11)
Interest income and other, net		2			3
Total other income (expense), net		(2)	(4)	(10)	(8)
Income before income taxes		87	38	150	107
Provision for income taxes		(18)	(13)	(45)	(42)
Net income		$ 69	$ 25	$ 105	$ 65
Earnings per share attributable to common stockholders (Note 4):
Basic		$ 0.50	$ 0.18	$ 0.76	$ 0.46
Diluted		$ 0.49	$ 0.18	$ 0.75	$ 0.46
Weighted average common shares outstanding (Note 4):
Basic		137,574	138,779	138,239	140,961
Diluted		140,513	139,388	140,151	141,681
[1]	Excludes amortization as follows:
[2]	Includes stock-based compensation expense as follows

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Costs and expenses:
Amortization of intangible assets	$ 8	$ 8	$ 24	$ 25
Depreciation	20	19	61	57
Amortization adjustment	16	16	50	45
Stock-based compensation:
Stock-based compensation	29	26	90	72
Selling and Marketing
Stock-based compensation:
Stock-based compensation	5	5	17	16
Technology and Content
Stock-based compensation:
Stock-based compensation	13	12	38	31
General and Administrative
Stock-based compensation:
Stock-based compensation	11	9	35	25
Acquired Technology
Costs and expenses:
Amortization of intangible assets	2	2	6	6
Website Development Costs
Costs and expenses:
Depreciation	$ 14	$ 14	$ 44	$ 39

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income		$ 69	$ 25	$ 105	$ 65
Other comprehensive income (loss):
Foreign currency translation adjustments	[1]	(5)	10	(14)	30
Total other comprehensive income (loss)		(5)	10	(14)	30
Comprehensive income		$ 64	$ 35	$ 91	$ 95
[1]	Foreign currency translation adjustments exclude income taxes due to our intention to indefinitely reinvest the earnings of our foreign subsidiaries in those operations.

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents (Note 6)	$ 663	$ 673
Short-term marketable securities (Note 6)		35
Accounts receivable and contract assets, net of allowance for doubtful accounts of $19 and $16, respectively (Note 3)	237	230
Income taxes receivable (Note 8)		30
Prepaid expenses and other current assets	26	25
Total current assets	926	993
Property and equipment, net of accumulated depreciation of $227 and $177, respectively	256	263
Intangible assets, net of accumulated amortization of $131 and $112, respectively	129	142
Goodwill	760	758
Deferred income taxes, net	28	16
Other long-term assets	93	100
TOTAL ASSETS	2,192	2,272
Current liabilities:
Accounts payable	22	8
Deferred merchant payables	204	156
Deferred revenue	73	60
Current portion of debt (Note 7)		7
Accrued expenses and other current liabilities	154	141
Total current liabilities	453	372
Long-term debt (Note 7)		230
Deferred income taxes, net	20	14
Other long-term liabilities	277	293
Total Liabilities	750	909
Commitments and contingencies (Note 9)
Stockholders’ equity: (Note 10)
Preferred stock, $0.001 par value Authorized shares: 100,000,000 Shares issued and outstanding: 0 and 0
Additional paid-in capital	1,010	926
Retained earnings	1,035	926
Accumulated other comprehensive income (loss)	(56)	(42)
Treasury stock-common stock, at cost, 12,056,688 and 9,474,490 shares, respectively	(547)	(447)
Total Stockholders’ Equity	1,442	1,363
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 2,192	$ 2,272

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Allowance for doubtful accounts	$ 19	$ 16
Property and equipment, accumulated depreciation	227	177
Intangible assets, accumulated amortization	$ 131	$ 112
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	1,600,000,000	1,600,000,000
Common stock, shares issued	136,869,883	135,617,263
Common stock, shares outstanding	124,813,195	126,142,773
Treasury stock, shares	12,056,688	9,474,490
Class B Common Stock
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	12,799,999	12,799,999
Common stock, shares outstanding	12,799,999	12,799,999

Condensed Consolidated Statem_4

Condensed Consolidated Statement of Changes in Stockholders' Equity - 9 months ended Sep. 30, 2018 - USD ($) $ in Millions	Total	Class B Common Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2017	$ 1,363			$ 926	$ 926	$ (42)	$ (447)
Beginning balance, shares at Dec. 31, 2017	126,142,773	12,799,999	135,617,263				(9,474,490)
Net income	$ 105				105
Cumulative effect adjustment from adoption of new accounting guidance (Note 2)	4				4
Other comprehensive loss	(14)					(14)
Issuance of common stock related to exercises of options and vesting of RSUs	3			3
Issuance of common stock related to exercises of options and vesting of RSUs, shares			1,252,620
Repurchase of common stock	$ (100)						$ (100)
Repurchase of common stock, shares	(2,582,198)						(2,582,198)
Withholding taxes on net share settlements of equity awards	$ (19)			(19)
Stock-based compensation	100			100
Ending balance at Sep. 30, 2018	$ 1,442			$ 1,010	$ 1,035	$ (56)	$ (547)
Ending balance, shares at Sep. 30, 2018	124,813,195	12,799,999	136,869,883				(12,056,688)

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net income	$ 105	$ 65
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment, including amortization of internal-use software and website development	61	57
Amortization of intangible assets	24	25
Stock-based compensation expense	90	72
Other, net	3	(6)
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, prepaid expenses and other assets	(16)	(58)
Accounts payable, accrued expenses and other liabilities	24	(2)
Deferred merchant payables	53	62
Income tax receivables/payables, net	15	5
Deferred revenue	15
Net cash provided by operating activities	374	220
Investing activities:
Capital expenditures, including internal-use software and website development	(45)	(50)
Purchases of marketable securities	(1)	(16)
Sales of marketable securities	59	105
Maturities of marketable securities	5	25
Acquisitions and other investments, net of cash acquired	(24)
Other investing activities, net	(12)
Net cash (used in) provided by investing activities	(18)	64
Financing activities:
Repurchase of common stock	(100)	(250)
Proceeds from exercise of stock options	3	3
Payment of withholding taxes on net share settlements of equity awards	(19)	(15)
Net cash used in financing activities	(354)	(163)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(12)	17
Net (decrease) increase in cash, cash equivalents and restricted cash	(10)	138
Cash, cash equivalents and restricted cash at beginning of period	673	612
Cash, cash equivalents and restricted cash at end of period	663	750
Supplemental disclosure of non-cash investing and financing activities:
Stock-based compensation capitalized with internal-use software and website development costs	10	10
2015 Credit Facility
Financing activities:
Proceeds from credit facility, net of financing costs	5	413
Payments to credit facility	(235)	(241)
2016 Credit Facility
Financing activities:
Payments to credit facility		$ (73)
Chinese Credit Facilities
Financing activities:
Payments to credit facility	(10)
Proceeds from credit facility	$ 2

Business Description and Basis

Business Description and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Business Description and Basis of Presentation	NOTE 1: BUSINESS DESCRIPTION AND BASIS OF PRESENTATION We refer to TripAdvisor, Inc. and our wholly-owned subsidiaries as “TripAdvisor”, “the Company”, “us”, “we” and “our” in these notes to the unaudited condensed consolidated financial statements. Description of Business TripAdvisor is an online travel company and our mission is to help people around the world to plan, book and experience the perfect trip. We seek to achieve our mission by providing users and travel partners a global platform about destinations, accommodations, travel activities and experiences, and restaurants that includes rich user-generated content, price comparison tools and online reservation and related services. TripAdvisor, Inc., by and through its subsidiaries, owns and operates a portfolio of leading online travel brands. Our flagship brand is TripAdvisor. TripAdvisor-branded websites include tripadvisor.com in the United States and localized versions of the website in 48 markets and 28 languages worldwide. In addition to the flagship TripAdvisor brand, we manage and operate the following more than 20 other travel media brands, connected by the common goal of providing users the most comprehensive travel-planning and trip-taking resources in the travel industry: www.airfarewatchdog.com, www.bokun.io, www.bookingbuddy.com, www.citymaps.com, www.cruisecritic.com, www.familyvacationcritic.com, www.flipkey.com, www.thefork.com (including www.lafourchette.com, www.eltenedor.com, www.iens.nl, and www.dimmi.com.au), www.gateguru.com, www.holidaylettings.co.uk, www.holidaywatchdog.com, www.housetrip.com, www.jetsetter.com, www.niumba.com, www.onetime.com, www.oyster.com, www.seatguru.com, www.smartertravel.com, www.tingo.com, www.vacationhomerentals.com, and www.viator.com. We manage our business in two reportable segments: Hotel and Non-Hotel. Our Non-Hotel segment consists of our Experiences, Restaurants, and Rentals offerings. During the first quarter of 2018 we renamed Attractions as “Experiences” and Vacation Rentals as “Rentals.” These changes had no impact on the composition of our segments or on any financial information. For further information on our segments and principal revenue streams within these segments refer to “Note 3: Revenue Recognition Segment Information Basis of Presentation The accompanying unaudited condensed consolidated financial statements present our results of operations, financial position and cash flows on a consolidated basis. The unaudited condensed consolidated financial statements include TripAdvisor, our wholly-owned subsidiaries, and entities we control, or in which we have a variable interest and are the primary beneficiary of expected cash profits or losses. All inter-company accounts and transactions have been eliminated in consolidation. One of our subsidiaries that operates in China has variable interests in affiliated entities in China in order to comply with Chinese laws and regulations, which restrict foreign investment in Internet content provision businesses. Although we do not own the capital stock of these Chinese affiliates, we consolidate their results as we are the primary beneficiary of the cash losses or profits of these variable interest affiliates and have the power to direct the activity of these affiliates. Our variable interest entities’ financials were not material for all periods presented. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) and include all normal and recurring adjustments that management of the Company considers necessary for a fair presentation of its financial position and operating results. Accounting Estimates We use estimates and assumptions in the preparation of our unaudited condensed consolidated financial statements in accordance with GAAP. Our estimates and assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of our unaudited condensed consolidated financial statements. These estimates and assumptions also affect the reported amount of net income or loss during any period. Our actual financial results could differ significantly from these estimates. The significant estimates underlying our unaudited condensed consolidated financial statements include: (i) recognition and recoverability of goodwill, definite-lived intangibles and other long-lived assets; and (ii) accounting for income taxes. Seasonality Traveler expenditures in the global travel market tend to follow a seasonal pattern. As such, expenditures by travel partners/advertisers to market to potential travelers and, therefore our financial performance, or revenue and profits, tend to be seasonal as well. Our financial performance tends to be seasonally highest in the second and third quarters of a year, as it is a key period for leisure travel research and trip-taking, which includes the seasonal peak in traveler hotel and rental stays, and tours and experiences taken, compared to the first and fourth quarters which represent seasonal low points. Further significant shifts in our business mix or adverse economic conditions could result in future seasonal patterns that are different from historical trends.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	NOTE 2: SIGNIFICANT ACCOUNTING POLICIES New Accounting Pronouncements Not Yet Adopted In August 2018, the SEC adopted a final rule under SEC Release No. 33-10532, Disclosure Update and Simplification This final rule is effective on November 5, 2018. As clarified by the SEC under Question 105.09 of the Exchange Act Forms C&DIs, which provides some relief to registrants that file Form 10-Q shortly after the final rule’s effective date, the Company will apply the disclosure change in stockholders’ equity analysis in its March 31, 2019, Form 10-Q. Additionally, the Company is in the process of evaluating the other disclosure impacts this final rule may have on its consolidated financial statement disclosures. In August 2018, the Financial Accounting Standards Board (“FASB”) issued new accounting guidance which require a customer in a cloud computing arrangement (i.e., hosting arrangement) that is a service contract to follow the internal-use software guidance to determine which implementation costs to capitalize as assets or expense as incurred. The accounting for the cost of the hosting component of the arrangement (i.e., service costs the customer pays for the cloud computing service) is not affected by this new guidance. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted, including adoption in any interim period. Entities have the option to apply the guidance retrospectively or prospectively to all implementation costs incurred after the date of adoption. We are currently considering our timing of adoption and the transition application method. We are also in the process of evaluating the impact of adopting this guidance on our consolidated financial statements and related disclosures. In June 2016, the FASB issued new accounting guidance on the measurement of credit losses for financial assets measured at amortized cost, which includes accounts receivable, and available-for-sale debt securities. For financial assets measured at amortized cost, this new guidance requires an entity to: (1) estimate its lifetime expected credit losses upon recognition of the financial assets and establish an allowance to present the net amount expected to be collected; (2) recognize this allowance and changes in the allowance during subsequent periods through net income; and (3) consider relevant information about past events, current conditions and reasonable and supportable forecasts in assessing the lifetime expected credit losses. For available-for-sale debt securities, this new guidance made several targeted amendments to the existing other-than-temporary impairment model, including: (1) requiring disclosure of the allowance for credit losses; (2) allowing reversals of the previously recognized credit losses until the entity has the intent to sell, is more-likely-than-not required to sell the securities or the maturity of the securities; (3) limiting impairment to the difference between the amortized cost basis and fair value; and (4) not allowing entities to consider the length of time that fair value has been less than amortized cost as a factor in evaluating whether a credit loss exists. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted, including interim periods within those fiscal years beginning after December 15, 2018. We are currently considering our timing of adoption and in the process of evaluating the impact of adopting this guidance on our consolidated financial statements and related disclosures. In February 2016, the FASB issued new guidance related to accounting for leases. The new standard requires the recognition of right-of-use (ROU) assets and lease liabilities on the balance sheet for all leases with a term longer than 12 months, which will initially be measured at the present value of the future lease payments over the lease term. For leases with a term of 12 months or less and that do not include an option to purchase the underlying asset or renew the lease term, that the lessee is reasonably certain to exercise, a lessee can make an accounting policy election by class of underlying asset to not recognize these leases on the balance sheet. Additionally, a lessee can also make an accounting policy election by class of underlying asset to not separate lease and non-lease components. Under the new guidance, leases will be classified as either finance or operating leases, with classification affecting the pattern and presentation of expenses and cash flows on our consolidated financial statements. The new guidance will require us to provide additional qualitative and quantitative disclosures regarding the amount, timing and uncertainty of cash flows arising from leases which include, among other things, the computation and disclosure of our weighted average remaining lease term and discount rate, cash paid for amounts included in the measurement of lease liabilities, and supplemental non-cash information on lease liabilities arising from obtaining the ROU assets. These disclosures are intended to provide supplemental information to the amounts recorded in the financial statements so that users can better understand the nature of an entity’s leasing activities. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. We will adopt the new standard on January 1, 2019 and use the effective date as our date of initial application based on the modified retrospective approach without adjusting the comparative periods presented. We expect to elect certain available practical expedients under the transition guidance at adoption. While we continue to assess all of the effects of adoption on our consolidated financial statements, including providing significant new disclosures about our leasing activities, we currently believe the primary effects of this new guidance relate to: (1) our existing operating leases for office space in which the new guidance requires us to recognize on our balance sheet the new ROU assets and lease liabilities; (2) our corporate headquarters lease, which is currently accounted for as a financing obligation, and of which we were deemed the owner for accounting purposes under the current build-to-suit lease guidance. The transition guidance for a build-to-suit lease arrangement requires the lessee to derecognize the assets and liabilities that were recognized solely as a result of a transaction’s build-to-suit designation under the current guidance, with any difference recorded as an adjustment to equity as of the adoption date. We will subsequently apply the general lessee guidance under the new standard to our corporate headquarters lease, including classifying it as either a finance or operating lease, and record a ROU asset and lease liability on the balance sheet, which will be initially measured at the present value of the remaining lease payments over the lease term. We are currently still assessing the quantitative impact this new guidance may have on our consolidated financial statements related to the aforementioned leases. We continue to update our accounting policies and accounting memos under the new guidance, and evaluate our existing population of contracts to ensure all contracts that meet the definition of a lease contract under the new standard are identified. We have completed the implementation of our lease accounting software to support our accounting process, financial reporting and the new additional quantitative and qualitative financial disclosure requirements and are now engaging in readiness activities during the fourth quarter for the January 1, 2019- go-live date. In addition, we are evaluating the impact of this new system implementation and new accounting guidance on our internal accounting process and controls. We will continue to provide updates on our assessment of the effect that this new lease guidance will have on our consolidated financial statements, disclosures, systems and related internal controls, and will disclose material effects, if any, when known. Recently Adopted Accounting Pronouncements In May 2017, the FASB issued new accounting guidance that clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications which will reduce diversity in practice. Under the new guidance, an entity will not apply modification accounting to a share-based payment award if the award’s fair value (or calculated value or intrinsic value, if those measurement methods are used), the award’s vesting conditions, and the award’s classification as an equity or liability instrument are the same immediately before and after the change. The guidance also states that an entity is not required to estimate the value of the award immediately before and after the change if the change does not affect any of the inputs to the model used to value the award. We adopted this guidance prospectively in the first quarter of 2018. We believe the new guidance will likely result in fewer changes to the terms of an award being accounted for as modifications. In January 2017, the FASB issued new accounting guidance to clarify the definition of a business and provide additional guidance to assist entities with evaluating whether transactions should be accounted for as asset acquisitions (or asset disposals) or business combinations (or disposals of a business). Under this new guidance, an entity first determines whether substantially all of the fair value of the assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. If this criterion is met, the transaction should be accounted for as an asset acquisition as opposed to a business combination. This distinction is important because the accounting for an asset acquisition significantly differs from the accounting for a business combination. This new guidance eliminates the requirement to evaluate whether a market participant could replace missing elements (e.g. inputs or processes), narrows the definition of outputs and requires that a business include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. We adopted this guidance in the first quarter of 2018 and it will be applied prospectively to any transactions occurring within and after the adoption date. In November 2016, the FASB issued new accounting guidance on the classification and presentation of restricted cash in the statement of cash flows to address the diversity in practice. This new guidance requires entities to show changes in cash, cash equivalents and restricted cash on a combined basis in the statement of cash flows. In addition, this accounting guidance requires a reconciliation of the total cash, cash equivalent and restricted cash in the statement of cash flows to the related captions in the balance sheet if cash, cash equivalents and restricted cash are presented in more than one line item in the balance sheet. We adopted this guidance in the first quarter of 2018 and applied it retrospectively to all prior periods presented in the financial statements as required under the new guidance. The adoption did not have a material impact on our consolidated financial statements and related disclosures. In October 2016, the FASB issued new accounting guidance on income tax accounting associated with intra-entity transfers of assets other than inventory. This accounting update, which is part of the FASB's simplification initiative, is intended to reduce diversity in practice and the complexity of tax accounting, particularly for those transfers involving intellectual property. This new guidance requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. We adopted this new guidance in the first quarter of 2018 on a modified retrospective basis. Accordingly, we recognized the cumulative effect of initial application of this new guidance as an adjustment to the opening balance of retained earnings, which was not material to our consolidated financial statements. In August 2016, the FASB issued new accounting guidance which clarifies how companies present and classify certain cash receipts and cash payments in the statement of cash flows. The new guidance specifically addresses the following cash flow topics in an effort to reduce diversity in practice: (1) debt prepayment or debt extinguishment costs; (2) settlement of zero-coupon bonds; (3) contingent consideration payments made after a business combination; (4) proceeds from the settlement of insurance claims; (5) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; (6) distributions received from equity method investees; (7) beneficial interests in securitization transactions; and (8) separately identifiable cash flows and application of the predominance principle. We adopted this new guidance in the first quarter of 2018 retrospectively and the adoption did not have an impact on our consolidated financial statements and related disclosures. In January 2016, the FASB issued new accounting guidance which amends the standard on the recognition and measurement of financial instruments. The FASB clarified certain aspects of this guidance by issuing an update for technical corrections and improvements related to this guidance in February 2018. The guidance (1) requires an entity to measure equity investments (except those accounted for under the equity method or those that result in consolidation of the investee) at fair value with changes in fair value recognized in net income rather than accumulated other comprehensive income on the balance sheet; (2) allows an entity to elect to measure the equity investments that do not have a readily determinable fair value using a new measurement alternative which measure these equity investments at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer; (3) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; and (4) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity’s evaluation of their other deferred tax assets. We adopted this guidance in the first quarter of 2018 and elected to prospectively account for our investments in equity securities of privately-held companies that do not have a readily determinable fair value using In May 2014, the FASB issued new accounting guidance on revenue from contracts with customers, or ASC 606, Revenue from Contracts with Customers In the first quarter of 2018, we adopted ASC 606 under the modified retrospective method for all contracts that were not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under the new revenue guidance, while prior period amounts are not adjusted and continue to be reported in accordance with our previous accounting policies under the historical revenue guidance, or ASC 605, Revenue Recognition We evaluated each of our revenue streams and applied ASC 606 as further discussed in “Note 3: Revenue Recognition for the commission We recognized the cumulative effect of initial application of ASC 606 as an adjustment to the opening balance of retained earnings. We recorded a net increase in opening retained earnings of $4 million as of January 1, 2018 due to the cumulative impact of adoption of the new revenue guidance and all other accounts were not materially impacted. There have been no changes to our significant accounting policies since December 31, 2017, other than noted above. See “Note 3: Revenue Recognition Significant Accounting Policies

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2018
Revenue From Contract With Customer [Abstract]
Revenue Recognition	NOTE 3: REVENUE RECOGNITION Revenue Recognition under ASC 606 We generate all of our revenue from contracts with customers. We recognize revenue when we satisfy a performance obligation by transferring control of the promised services to a customer in an amount that reflects the consideration that we expect to receive in exchange for those services. When we act as an agent in the transaction under ASC 606, we recognize revenue for only our commission on the arrangement. We determine revenue recognition through the following steps: (1) Identification of the contract, or contracts, with a customer (2) Identification of the performance obligations in the contract (3) Determination of the transaction price (4) Allocation of the transaction price to the performance obligations in the contract (5) Recognition of revenue when, or as, we satisfy a performance obligation. At contract inception, we assess the services promised in our contracts with customers and identify a performance obligation for each promise to transfer to the customer a service (or bundle of services) that is distinct. To identify the performance obligations, we consider all of the services promised in the contract regardless of whether they are explicitly stated or are implied by customary business practices. We have provided qualitative information about our performance obligations for our principal revenue streams discussed below. There was no significant revenue recognized in the three and nine months ended September 30, 2018 related to performance obligations satisfied in prior periods. We have applied a practical expedient and do not disclose the value of unsatisfied performance obligations that have an original expected duration of less than one year, and we do not have any material unsatisfied performance obligations over one year. The value related to our remaining or partially satisfied performance obligations relates to subscription services that are satisfied over time or services that are recognized at a point in time, but not yet achieved. Our timing of services, invoicing and payments are discussed in more detail below and do not include a significant financing component. Our customer invoices are generally due 30 days from the time of invoicing. We recognize an asset for the incremental costs of obtaining a contract with a customer if we expect the benefit of those costs to be longer than one year. Although the substantial majority of our contract costs have an amortization period of less than one year, we have determined contract costs arising from certain sales incentives have an amortization period in excess of one year given the high likelihood of contract renewal. Sales incentives are not paid upon renewal of these contracts and therefore are not commensurate with the initial sales incentive costs. Total capitalized costs to obtain a contract were approximately $1 million as of September 30, 2018. We amortize these contract costs on a straight-line basis over the estimated customer life, which is based on historical . Amortization expense recorded to selling and marketing during the three and nine months ended September 30, 2018 was not material. We assess such assets for impairment when events or circumstances indicate that the carrying amount may not be recoverable. The recognition of revenue may require the application of judgment related to the determination of the performance obligations, the timing of when the performance obligations are satisfied and other areas. The determination of our performance obligations does not require significant judgment given that we generally do not provide multiple services to a customer in a transaction, and the point in which control is transferred to the customer is readily determinable. In instances where we recognize revenue over time, we generally have either a subscription service that is recognized over time on a straight-line basis using the time-elapsed output method, or based on other output measures that provide a faithful depiction of the transfer of our services. When an estimate for cancellations is included in the transaction price, we base our estimate on historical cancellation rates. There have been no significant adjustments to our cancellation Hotel Segment TripAdvisor-branded Click-based Advertising and Transaction Revenue . Our largest source of Hotel segment revenue is generated from click-based advertising on TripAdvisor-branded websites, which is primarily comprised of contextually-relevant booking links to our travel partners’ sites. Our click-based travel partners are predominantly online travel agencies, or OTAs, and direct suppliers in the hotel category. Click-based advertising is generally priced on a cost-per-click, or “CPC”, basis, with payments from advertisers determined by the number of users who click on a link multiplied by the price that partner is willing to pay for that click, or hotel shopper lead. CPC rates that our travel partners are willing to pay are determined in a dynamic, competitive auction process, or metasearch auction. We record click-based advertising revenue as the click occurs and traveler leads are sent to the travel partner websites as our performance obligation is fulfilled at that time. Click-based revenue is generally billed to our travel partners on a monthly basis consistent with the timing of the service. Transaction revenue is generated from our instant booking feature, which enables hotel shoppers to book directly with a travel partner, or the merchant of record, without leaving our website. We earn a commission from our travel partner for a user that completes a hotel reservation on our website. Our instant booking revenue includes (i) (ii) The travel partner provides the service to the traveler and we act as an agent under ASC 606. TripAdvisor-branded Display-based Advertising and Subscription Revenue . Travel partners can promote their brands in a contextually-relevant manner through a variety of display-based advertising placements on our websites. Our display-based advertising clients are predominately direct suppliers of hotels, airlines and cruises, as well as destination marketing organizations. We also sell display-based advertising to OTAs and other travel related businesses, as well as advertisers from non-travel categories. Display-based advertising is sold predominantly on a cost per thousand impressions, or CPM, basis. The performance obligation in our display-based advertising business is to display a number of advertising impressions on our websites and we recognize revenue for impressions as they are delivered. Services are generally billed monthly. We have applied the practical expedient to measure progress toward completion, as we have the right to invoice the customer in an amount that directly corresponds with the value to the customer of our performance to date, which is measured based on impressions delivered. In addition, we offer subscription-based advertising to hotels, B&Bs and other specialty lodging properties. Our performance obligation is generally to enable subscribers to advertise their business on our website, including such information as a website URL, email address and phone number, as well as other information. Subscription advertising services are predominantly sold for a flat fee for a contracted period of time of one year or less and revenue is recognized on a straight-line basis over the period of the subscription service as efforts are expended evenly throughout the contract period. Subscription advertising services are generally billed in advance of service. When prepayments are received, we recognize deferred revenue for the amount of prepayment in excess of revenue recognized until the performance obligation is satisfied. Other Hotel Revenue. Our other Hotel revenue primarily includes revenue from non-TripAdvisor-branded websites, such as www.bookingbuddy.com, www.cruisecritic.com, and www.onetime.com, which primarily includes click-based advertising and display-based advertising revenue. The performance obligations and timing of customer payments for these brands and methods of recognizing revenue are generally consistent with click-based advertising or display-based advertising revenue, as described above. Non-Hotel Segment We provide information and services for users to research, book and experience activities and attractions in popular travel destinations both through Viator, our dedicated Experiences offering, and on our TripAdvisor website and applications. We also power travel activities and experiences booking capabilities to users for affiliate partners, including some of the world’s top airlines, hotel chains and online and offline travel agencies. We work with local tour or travel activities/experiences operators (“the supplier”) to provide our users with access to book tours, activities and experiences (“the activity”) in popular destinations worldwide. We generate commissions for each booking transaction we facilitate through our online reservation system. We provide post-booking service to the user until the time of the activity, which is the completion of the performance obligation. Revenue is recognized at the time that the activity occurs. We do not control the activity before the supplier provides the activity to our users and therefore act as agent for nearly all of these transactions under ASC 606. We do not control the service and act as an agent for these transactions under ASC 606. We also provide information and services for users to research and book restaurants in popular travel destinations through our dedicated restaurant reservations offering, TheFork, and on our TripAdvisor website and applications. TheFork is an online restaurant booking platform operating on a number of websites (including www.lafourchette.com, www.eltenedor.com, www.iens.nl and www.dimmi.com.au), with a network of restaurant partners located primarily across Europe and Australia. Our bookable restaurants are available on www.thefork.com and on TripAdvisor-branded websites and mobile applications. We primarily generate transaction fees (or per seated diner fees) that are paid by restaurants for diners seated primarily from bookings through TheFork’s online reservation system. The transaction fee is recognized as revenue after the reservation is fulfilled, or as diners are seated by our restaurant customers. Revenue is billed monthly when the transaction fees are payable, which is at the time the diner is seated. To a lesser extent, we also generate subscription fees for access to certain online reservation management services and marketing analytic tools provided by TheFork and TripAdvisor. As the performance obligation is to provide restaurants with access to these services over the subscription period, subscription fee revenue is recognized over the period of the subscription service on a straight-line basis as efforts are expended evenly throughout the contract period. Subscription fees are generally billable in advance of service. When prepayments are received, we recognize deferred revenue for the amount of prepayment in excess of revenue recognized until the performance obligation is satisfied. In addition, we provide information and services for users to research and book vacation and short-term rental properties, including full home rentals, condominiums, villas, beach rentals, cabins and cottages. Our Rentals offering generates revenue primarily by offering individual property owners and managers the ability to list their properties on our websites and mobile applications thereby connecting homeowners with travelers through a free-to-list, commission-based option or, to a lesser extent, by an annual subscription-based fee structure. These properties are listed on www.flipkey.com, www.holidaylettings.co.uk, www.housetrip.com, www.niumba.com, and www.vacationhomerentals.com, and on our TripAdvisor-branded websites and mobile applications. We earn commissions associated with rental transactions through our free-to-list model from both the traveler and the property owner or manager. We provide post-booking service to the travelers, property owners and managers until the time the rental commences, which is the time the performance obligation is completed. Revenue from transaction fees is recognized at the time that the rental commences. We act as an agent, under ASC 606, in the transactions as we do not control any properties before the property owner provides the accommodation to the traveler and do not have inventory risk. Practical Expedients and Exemptions We expense costs to obtain a contract as incurred, such as sales incentives, when the amortization period would have been one year or less. We do not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which we recognize revenue at the amount to which we have the right to invoice for services performed. Impact of Adoption of ASC 606 The impact of this new revenue recognition guidance on our unaudited condensed consolidated statement of operations for the three and nine months ended September 30, 2018 was as follows: Three months ended September 30, 2018 INCOME STATEMENT As Reported - ASC 606 September 30, 2018 Impact of Accounting ASC 606 Adjusted - ASC 605 September 30, 2018 (in millions, except per share amounts) Revenue $ 458 $ 3 $ 461 Operating income 89 3 92 Income before income taxes 87 3 90 Provision for income taxes (18 ) - (18 ) Net income 69 3 72 Basic EPS 0.50 0.02 0.52 Diluted EPS 0.49 0.02 0.51 Nine months ended September 30, 2018 INCOME STATEMENT As Reported - ASC 606 September 30, 2018 Impact of Accounting ASC 606 Adjusted - ASC 605 September 30, 2018 (in millions, except per share amounts) Revenue $ 1,269 $ (3 ) $ 1,266 Operating income 160 (3 ) 157 Income before income taxes 150 (3 ) 147 Provision for income taxes (45 ) 1 (44 ) Net income 105 (2 ) 103 Basic EPS 0.76 (0.01 ) 0.75 Diluted EPS 0.75 (0.01 ) 0.74 The impact of the new guidance was not meaningful as of and for the nine months ended September 30, 2018 for the unaudited condensed consolidated balance sheet and unaudited condensed consolidated statement of cash flows, respectively. Disaggregation of Revenue We disaggregate revenue from contracts with customers into major products/revenue sources. We have determined that disaggregating revenue into these categories achieves the disclosure objective to depict how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. As noted in “Note 12: Segment Information Three months ended September 30, 2018 Nine months ended September 30, 2018 Major products/revenue sources: (in millions) TripAdvisor-branded click-based advertising and transaction revenue $ 194 $ 583 TripAdvisor-branded display-based advertising and subscription revenue 81 231 Other hotel revenue 30 103 Total Hotel Revenue (1) 305 917 Non-Hotel Revenue (1) 153 352 Total Revenue $ 458 $ 1,269 (1) Our revenue is recognized primarily at a point in time for both our Hotel and Non-Hotel segments. Contract Balances The following table provides information about the opening and closing balances of accounts receivables and contract assets from contracts with customers (in millions): September 30, 2018 December 31, 2017 Accounts receivable 227 230 Contract assets 10 - Total $ 237 $ 230 Accounts receivable are recognized when the right to consideration becomes unconditional. Contract assets are rights to consideration in exchange for services that we have transferred to a customer when that right is conditional on something other than the passage of time, such as commission payments that are contingent upon the completion of the service by the principal in the transaction. Contract liabilities generally include payments received in advance of performance under the contract, and are realized as revenue as the performance obligation to the customer is satisfied, which we present as deferred revenue on our unaudited condensed consolidated balance sheets. As of January 1, 2018, we had $59 million recorded as deferred revenue on our unaudited condensed consolidated balance sheet, of which $8 million and $53 million was recognized in revenue, during the three and nine months ended September 30, 2018, respectively. The difference between the opening and closing balances of our contract assets and deferred revenue primarily results from the timing differences between when we receive customer payments and the time in which we satisfy our performance obligations. There were no significant changes in contract assets or deferred revenue during the nine months ended September 30, 2018 related to business combinations, impairments, cumulative catch-ups or other material adjustments.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	NOTE 4: EARNINGS PER SHARE Basic Earnings Per Share Attributable to Common Stockholders We compute basic earnings per share, or Basic EPS, by dividing net income by the weighted average number of common shares outstanding during the period. We compute the weighted average number of common shares outstanding during the reporting period using the total of common stock and Class B common stock outstanding as of the last day of the previous year end reporting period plus the weighted average of any additional shares issued and outstanding less the weighted average of any common shares repurchased during the reporting period. Diluted Earnings Per Share Attributable to Common Stockholders Diluted earnings per share, or Diluted EPS, includes the potential dilution of common equivalent shares outstanding that could occur from stock-based awards and other stock-based commitments using the treasury stock method. We compute Diluted EPS by dividing net income by the sum of the weighted average number of common and common equivalent shares outstanding during the period. We computed the weighted average number of common and common equivalent shares outstanding during the period using the sum of (i) the number of shares of common stock and Class B common stock used in the basic earnings per share calculation as indicated above, and (ii) if dilutive, the incremental weighted average common stock that we would issue upon the assumed exercise of outstanding common equivalent shares, primarily related to stock options and the vesting of restricted stock units using the treasury stock method, and (iii) if dilutive, performance-based and market-based awards based on the number of shares that would be issuable as of the end of the reporting period assuming the end of the reporting period was also the end of the contingency period. Under the treasury stock method, the assumed proceeds calculation includes the actual proceeds to be received from the employee upon exercise of outstanding equity awards and the average unrecognized compensation cost during the period. The treasury stock method assumes that a company uses the proceeds from the exercise of an equity award to repurchase common stock at the average market price for the reporting period. Below is a reconciliation of the weighted average number of shares of common stock outstanding in calculating Diluted EPS (shares in thousands and dollars in millions, except per share amounts) for the periods presented: Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Numerator: Net income $ 69 $ 25 $ 105 $ 65 Denominator: Weighted average shares used to compute Basic EPS 137,574 138,779 138,239 140,961 Weighted average effect of dilutive securities: Stock options 518 193 305 312 RSUs/MSUs 2,421 416 1,607 408 Weighted average shares used to compute Diluted EPS 140,513 139,388 140,151 141,681 Basic EPS $ 0.50 $ 0.18 $ 0.76 $ 0.46 Diluted EPS $ 0.49 $ 0.18 $ 0.75 $ 0.46 Potential common shares, consisting of outstanding stock options and restricted stock units (“RSUs”), totaling approximately 3.4 million shares and 7.1 million shares for the three and nine months ended September 30, 2018, respectively, and approximately 6.4 million shares and 6.6 million shares for the three and nine months ended September 30, 2017, respectively, have been excluded from the calculation of Diluted EPS because their effect would have been antidilutive. In addition, potential common shares, consisting of performance-based awards, totaling approximately 0.5 million shares for both the three and nine months ended September 30, 2018, respectively, and approximately 0.1 million shares for both the three and nine months ended September 30, 2017, respectively, for which all targets required to trigger vesting had not been achieved, were excluded from the calculation of weighted average shares used to compute Diluted EPS for those reporting periods. The earnings per share amounts are the same for common stock and Class B common stock because the holders of each class are legally entitled to equal per share distributions whether through dividends or in liquidation.

Stock Based Awards and Other Eq

Stock Based Awards and Other Equity Instruments	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Based Awards and Other Equity Instruments	NOTE 5: STOCK BASED AWARDS AND OTHER EQUITY INSTRUMENTS On June 21, 2018, our stockholders approved the 2018 Stock and Annual Incentive Plan (the “2018 Plan”) primarily for the purpose of providing sufficient reserves of shares of our common stock to ensure our ability to continue to provide new hires, employees and management with equity incentives. The number of shares reserved and available for issuance under the 2018 Plan is 6,000,000 plus the number of shares available for issuance (and not subject to outstanding awards) under the TripAdvisor, Inc. Amended and Restated 2011 Stock and Annual Incentive Plan (the “2011 Plan”), Stock-Based Compensation Expense The following table presents the amount of stock-based compensation expense related to stock-based awards, primarily stock options and RSUs, on our unaudited condensed consolidated statements of operations during the periods presented: Three months ended Nine months ended September 30, September 30, 2018 2017 2018 2017 (in millions) (in millions) Selling and marketing $ 5 $ 5 $ 17 $ 16 Technology and content 13 12 38 31 General and administrative 11 9 35 25 Total stock-based compensation 29 26 90 72 Income tax benefit from stock-based compensation (7 ) (9 ) (22 ) (27 ) Total stock-based compensation, net of tax effect $ 22 $ 17 $ 68 $ 45 We capitalized $3 million and $10 million of stock-based compensation expense as internal-use software and website development costs during both the three and nine months ended September 30, 2018 and 2017, respectively. Stock-Based Award Activity and Valuation 2018 Stock Option Activity During the nine months ended September 30, 2018, we granted 632,114 service-based non-qualified stock options under both the 2018 Plan and its predecessor, the 2011 Plan. Our stock options generally have a term of ten years from the date of grant and typically vest equally over a four-year requisite service period. A summary of our stock option activity during the nine months ended September 30, 2018, is presented below: Weighted Weighted Average Average Exercise Remaining Aggregate Options Price Per Contractual Intrinsic Outstanding Share Life Value (in thousands) (in years) (in millions) Options outstanding at December 31, 2017 6,853 $ 52.78 Granted 632 41.87 Exercised (1) (619 ) 36.46 Cancelled or expired (266 ) 51.93 Options outstanding at September 30, 2018 6,600 $ 53.29 6.3 $ 44 Exercisable as of September 30, 2018 3,764 $ 58.79 4.5 $ 19 Vested and expected to vest after September 30, 2018 (2) 6,600 $ 53.29 6.3 $ 44 (1) Inclusive of 458,413 options which were not converted into shares due to net share settlement in order to cover the aggregate exercise price and the required amount of employee withholding taxes. Potential shares that had been convertible under stock options that were withheld under net share settlement remain in the authorized but unissued pool under the 2018 Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows. (2) The Company accounts for forfeitures as they occur, rather than estimate expected forfeitures as allowed under GAAP and therefore do not include a forfeiture rate in our vested and expected to vest calculation unless necessary for a performance condition award. Aggregate intrinsic value represents the difference between the closing stock price of our common stock and the exercise price of outstanding, in-the-money options. Our closing stock price as reported on NASDAQ as of September 30, 2018 was $51.07. The total intrinsic value of stock options exercised was $7 million and $8 million, for the nine months ended September 30, 2018 and 2017, respectively. The fair value of stock option grants has been estimated at the date of grant using the Black–Scholes option pricing model with the following weighted average assumptions for the periods presented: Three months ended Nine months ended September 30, September 30, 2018 2017 2018 2017 Risk free interest rate 2.78 % 1.84 % 2.66 % 1.90 % Expected term (in years) 5.45 5.32 5.45 5.35 Expected volatility 40.22 % 41.31 % 42.26 % 41.52 % Expected dividend yield — % — % — % — % The weighted-average grant date fair value of options granted was $23.12 and $17.72 for the three and nine months ended September 30, 2018, respectively. The weighted-average grant date fair value of options granted was $15.49 and $17.16 for the three and nine months ended September 30, 2017, respectively. The total fair value of stock options vested was $35 million and $39 million for the nine months ended September 30, 2018 and 2017, respectively. Cash received from stock option exercises was $3 million for both the nine months ended September 30, 2018 and 2017, respectively. 2018 RSU Activity During the nine months ended September 30, 2018, we granted 3,263,455 of primarily service-based RSUs under the 2018 Plan and its predecessor, the 2011 Plan, which typically vest over a four-year requisite service period. A summary of our RSU activity for service-based and performance-based awards during the nine months ended September 30, 2018, is presented below: Weighted Average Grant- Aggregate RSUs Date Fair Intrinsic Outstanding Value Per Share Value (in thousands) (in millions) Unvested RSUs outstanding as of December 31, 2017 (1) 6,015 $ 48.14 Transfer (1) (213 ) 30.04 Granted 3,263 42.19 Vested and released (2) (1,454 ) 53.38 Cancelled (715 ) 46.51 Unvested RSUs outstanding as of September 30, 2018 6,896 $ 44.95 $ 352 Expected to vest after September 30, 2018 (3) 6,896 $ 44.95 $ 352 (1) RSUs outstanding as of December 31, 2017 include 213,000 market-based restricted stock units (“MSUs”) awarded to the Company’s CEO in November 2017. This award has been transferred to the MSU activity table below. (2) Inclusive of 378,235 RSUs withheld due to net share settlement to satisfy required employee tax withholding requirements. Potential shares which had been convertible under RSUs that were withheld under net share settlement remain in the authorized but unissued pool under the 2018 Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows. (3) The Company accounts for forfeitures as they occur, rather than estimate expected forfeitures as allowed under GAAP and therefore do not include a forfeiture rate in our expected to vest calculation unless necessary for a performance condition award. A summary of our RSU activity for MSUs, during the nine months ended September 30, 2018 is presented below: Weighted Average Grant- Aggregate MSUs Date Fair Intrinsic Outstanding Value Per Share Value (in thousands) (in millions) Unvested MSUs outstanding as of December 31, 2017 (1) 213 $ 30.04 Granted (2) 71 59.40 Vested and released ― ― Cancelled ― ― Unvested MSUs outstanding as of September 30, 2018 284 $ 37.41 $ 15 ( 1) Represents 213,000 MSUs awarded to the Company’s CEO in November 2017. (2) MSUs provide for vesting based upon the Company’s total shareholder return, or TSR, performance over the period commencing January 1, 2018 through December 31, 2020 relative to the TSR performance of the Nasdaq Composite Total Return Index. A Monte-Carlo simulation model, which simulated the present value of the potential outcomes of future stock prices and TSR of the Company and the Nasdaq Composite Total Return Index over the performance period, was used to calculate the grant-date fair value of these awards. The estimated grant-date fair value of these awards is being amortized on a straight-line basis over the requisite service period through December 31, 2020. Based upon actual attainment relative to the target performance metric, the grantee has the ability to receive up to 200% of the target number of MSUs originally granted, or to be issued none at all. These MSUs were granted under the 2011 Plan. Total current income tax benefits associated with the exercise or settlement of TripAdvisor stock-based awards held by our employees were $1 million and $10 million during the three and nine months ended September 30, 2018, respectively, and $1 million and $17 million during the three and nine months ended September 30, 2017, respectively. Unrecognized Stock-Based Compensation A summary of our remaining unrecognized stock-based compensation expense and the weighted average remaining amortization period at September 30, 2018 related to our non-vested equity awards is presented below (in millions, except in years information): Stock Options RSUs MSUs Unrecognized compensation expense $ 39 $ 245 $ 8 Weighted average period remaining (in years) 3.0 2.8 2.3

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2018
Investments All Other Investments [Abstract]
Financial Instruments	NOTE 6: FINANCIAL INSTRUMENTS Cash, Cash Equivalents, Restricted Cash and Marketable Securities The following tables show our cash, cash equivalents, restricted cash and short-term and long-term available-for-sale marketable debt securities, by major security type, that are measured at fair value on a recurring basis and were categorized using the fair value hierarchy, as well as their classification on September 30, 2018 Amortized Cost Fair Value (2) Cash, Cash Equivalents and Restricted Cash Short-Term Marketable Securities Long-Term Marketable Securities (3) Cash and restricted cash (1) $ 421 $ 421 $ 421 $ - $ - Level 1: Money market funds 242 242 242 - - Total $ 663 $ 663 $ 663 $ - $ - December 31, 2017 Amortized Cost Fair Value (2) Cash, Cash Equivalents and Restricted Cash Short-Term Marketable Securities Long-Term Marketable Securities (3) Cash and restricted cash (1) $ 663 $ 663 $ 663 $ - $ - Level 1: Money market funds 1 1 1 - - Level 2: U.S. agency securities 11 11 - 6 5 U.S. treasury securities 1 1 - 1 - Certificates of deposit 2 2 - 2 - Commercial paper 11 11 9 2 - Corporate debt securities 46 46 - 24 22 Subtotal 71 71 9 35 27 Total $ 735 $ 735 $ 673 $ 35 $ 27 (1) As of September 30, 2018 and December 31, 2017, our restricted cash, which primarily consists of escrowed security deposits, was not material and is included in other long-term assets on our unaudited condensed consolidated balance sheets. (2) As of September 30, 2018 and December 31, 2017, any unrealized gains or losses related to our marketable securities were not material. (3) Long-term marketable securities are included in other long-term assets on our unaudited condensed consolidated balance sheets. Our cash and cash equivalents consist of cash on hand in global financial institutions, money market funds and marketable securities with maturities of 90 days or less at the date of purchase. The remaining maturities of our long-term marketable securities range from one to three years and our short-term marketable securities include maturities that were greater than 90 days at the date purchased and have 12 months or less remaining at September 30, 2018 and December 31, 2017, respectively. For assets and liabilities required to be reported at fair value, GAAP provides a hierarchy that prioritizes inputs to valuation techniques used to measure fair value into three broad levels: Level 1—Valuations are based on quoted market prices for identical assets and liabilities in active markets. Level 2—Valuations are based on observable inputs other than quoted market prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data. Level 3—Valuations are based on unobservable inputs reflecting our own assumptions, consistent with reasonably available assumptions made by other market participants. These valuations require significant judgment. We classify our cash, cash equivalents, restricted cash and marketable securities within Level 1 and Level 2 as we value these financial instruments using quoted market prices (Level 1) or alternative pricing sources (Level 2). The valuation technique we used to measure the fair value of money market funds was derived from quoted prices in active markets for identical assets or liabilities. Fair values for Level 2 marketable securities are considered “Level 2” valuations because they are obtained from independent pricing sources for identical or comparable instruments, rather than direct observations of quoted prices in active markets. Our procedures include controls to ensure that appropriate fair values are recorded, including comparing the fair values obtained from our independent pricing services against fair values obtained from another independent source. There were no material realized gains or losses related to sales of our marketable securities for the three and nine months ended September 30, 2018 and 2017, respectively. Realized gains and losses on the sale of securities are determined by specific identification of each security’s cost basis. We consider any unrealized loss position in our available-for-sale marketable debt securities to be temporary in nature and do not consider any of these investments other-than-temporarily impaired as of September 30, 2018 and December 31, 2017. Derivative Financial Instruments We use foreign currency forward contracts to reduce the effects of foreign currency exchange rate fluctuations on our cash flows primarily for the Euro versus the U.S. Dollar. We do not use derivatives for trading or speculative purposes. Counterparties to foreign currency exchange derivatives consist of major international financial institutions. We monitor our positions and the credit ratings of the counterparties involved and, by policy limits, the amount of credit exposure to any one party. Our foreign currency forward contracts, which we have entered into to date, have not been designated as hedges and typically have had current maturities of less than 90 days. Derivative financial instruments are carried at fair value on our unaudited condensed consolidated balance sheets. Any gain or loss resulting from the change in fair value of the foreign currency forward contracts has been recognized in our unaudited condensed consolidated statement of operations in “Interest income and other, net.” All gains and losses for the three months ended September 30, 2018 were not material. We recorded a net loss of $3 million for the nine months ended September 30, 2018, related to our settled forward contracts in our unaudited condensed consolidated statement of operations in “Interest income and other, net.” All gains and losses for both the three and nine months ended September 30, 2017, respectively, were not material. The Company had no outstanding foreign currency forward contracts as of September 30, 2018 and December 31, 2017, respectively. Other Financial Instruments Other financial instruments not measured at fair value on a recurring basis include accounts receivable and contract assets, accounts payable, deferred merchant payables, short-term debt, accrued expenses and other current liabilities and long-term debt. The carrying amount of these financial instruments, with the exception of long-term debt, approximate their fair value because of the short maturity of these instruments as reported on our unaudited condensed consolidated balance sheets as of September 30, 2018 and December 31, 2017. The carrying value of the long-term debt from our 2015 Credit Facility bears interest at a variable rate and therefore is also considered to approximate its fair value. In addition, we hold investments in equity securities of privately-held companies that do not have a readily determinable fair value. As of both September 30, 2018 and December 31, 2017, the total carrying value of our equity investments in these privately-held companies were $12 million and are included in “Other long-term assets” on our unaudited condensed consolidated balance sheets. Our policy is to measure these investments at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. On a quarterly basis, we perform a qualitative assessment considering impairment indicators to evaluate whether these investments are impaired and also monitor for any observable price changes. During the three and nine months ended September 30, 2018, we did not have any impairment loss on these equity investments. The Company recognized a loss of $2 million related to an investment in a privately-held company during the three and nine months ended September 30, 2017 in “Interest income and other, net” on our unaudited condensed consolidated statements of operations. The Company did not have any material assets or liabilities measured at fair value on a recurring basis using the Level 3 unobservable inputs at both September 30, 2018 and December 31, 2017.

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt	NOTE 7: DEBT 2015 Credit Facility We are party to a five year credit agreement with a group of lenders which, among other things, provides for a $1.2 billion unsecured revolving credit facility (the “2015 Credit Facility”) with a maturity date of May 12, 2022. Borrowings under the 2015 Credit Facility generally bear interest, at the Company’s option, at a rate per annum equal to either (i) the Eurocurrency Borrowing rate, or the adjusted LIBO rate for the interest period in effect for such borrowing; plus an applicable margin ranging from 1.25% to 2.00% (“Eurocurrency Spread”), based on the Company’s leverage ratio; or (ii) the Alternate Base Rate (“ABR”) Borrowing, which is the greatest of (a) the Prime Rate in effect on such day, (b) the New York Fed Bank Rate in effect on such day plus 1/2 of 1.00% per annum and (c) the Adjusted LIBO Rate (or LIBO rate multiplied by the Statutory Reserve Rate) for an interest period of one month plus 1.00%; in addition to an applicable margin ranging from 0.25% to 1.00% (“ABR Spread”), based on the Company’s leverage ratio. The Company may borrow from the 2015 Credit Facility in U.S. dollars, Euros and British pound sterling. During the nine months ended September 30, 2018, the Company borrowed an additional $5 million and repaid $235 million of our outstanding borrowings on the 2015 Credit Facility. These net repayments were primarily made from a one-time cash repatriation of $325 million of foreign earnings to the United States during the first quarter of 2018. As of September 30, 2018, there were no outstanding borrowings under the 2015 Credit Facility. We are required to pay a quarterly commitment fee, at an applicable rate ranging from 0.15% to 0.30%, on the daily unused portion of the revolving credit facility for each fiscal quarter and additional fees in connection with the issuance of letters of credit. As of September 30, 2018, our unused revolver capacity was subject to a commitment fee of 0.15%, given the Company’s leverage ratio. The 2015 Credit Facility includes $15 million of borrowing capacity available for letters of credit and $40 million for Swingline borrowings on same-day notice. As of September 30, 2018, we had issued $3 million of outstanding letters of credit under the 2015 Credit Facility. Total interest expense and commitment fees recorded on our 2015 Credit Facility were not material for the three months ended September 30, 2018. We recorded total interest expense and commitment fees on our 2015 Credit Facility of $2 million for the nine months ended September 30, 2018 and $2 million and $4 million for the three and nine months ended September 30, 2017, respectively, to “Interest expense” on our unaudited condensed consolidated statements of operations. All unpaid interest and commitment fee amounts as of September 30, 2018 and December 31, 2017, respectively, were not material. There is no specific repayment date prior to the maturity date for borrowings under this credit agreement. We may voluntarily repay any outstanding borrowing under the 2015 Credit Facility at any time without premium or penalty, other than customary breakage costs with respect to Eurocurrency loans. Additionally, the Company believes that the likelihood of the lender exercising any subjective acceleration rights, which would permit the lenders to accelerate repayment of any outstanding borrowings, is remote. As such, we classify any borrowings under this facility as long-term debt. The 2015 Credit Facility contains a number of covenants that, among other things, restrict our ability to: incur additional indebtedness, create liens, enter into sale and leaseback transactions, engage in mergers or consolidations, sell or transfer assets, pay dividends and distributions, make investments, loans or advances, prepay certain subordinated indebtedness, make certain acquisitions, engage in certain transactions with affiliates, amend material agreements governing certain subordinated indebtedness, and change our fiscal year. The 2015 Credit Facility also requires us to maintain a maximum leverage ratio and contains certain customary affirmative covenants and events of default, including a change of control. If an event of default occurs, the lenders under the 2015 Credit Facility will be entitled to take various actions, including the acceleration of all amounts due under the 2015 Credit Facility. As of September 30, 2018, we were in compliance with all of our debt covenants. 2016 Credit Facility We were party to an uncommitted facility agreement which provided for a $73 million unsecured revolving credit facility (the “2016 Credit Facility”) with no specific expiration date. We initially borrowed $73 million from this uncommitted credit facility in 2016 and repaid the full amount during the three months ended March 31, 2017. As of December 31, 2017, there were no outstanding borrowings under the 2016 Credit Facility. In June 2018, the Company terminated the 2016 Credit Facility. We had no outstanding borrowings under the 2016 Credit Facility at the time of termination. Chinese Credit Facilities As of September 30, 2018, in addition to our 2015 Credit Facility, we maintain two credit facilities in China (jointly, the “Chinese Credit Facilities”). We are party to a $30 million, one-year revolving credit facility with Bank of America (the “Chinese Credit Facility—BOA”) that is currently subject to review on a periodic basis with no specific expiration period. Borrowings under our Chinese Credit Facility – BOA generally bear interest at a rate based on People’s Bank of China benchmark, including certain adjustments which may be made in accordance with market conditions at the time of borrowing. As of September 30, 2018 and December 31, 2017, there were no outstanding borrowings under our Chinese Credit Facility—BOA. We are also party to a RMB 70,000,000 (approximately $10 million) one-year revolving credit facility with J.P. Morgan Chase Bank (“Chinese Credit Facility-JPM”). Our Chinese Credit Facility—JPM generally bears interest at a rate based on People’s Bank of China benchmark, including certain adjustments which may be made in accordance with market conditions at the time of borrowing. As of December 31, 2017, we had $7 million of outstanding borrowings from the Chinese Credit Facility – JPM at a weighted average interest rate of 5.00%. During the nine months ended September 30, 2018, we borrowed an additional $2 million and repaid in full the outstanding borrowings under our Chinese Credit Facility-JPM of $10 million.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 8: INCOME TAXES Each interim period is considered an integral part of the annual period and, accordingly, we measure our income tax expense using an estimated annual effective tax rate. An enterprise is required, at the end of each interim reporting period, to make its best estimate of the annual effective tax rate for the full fiscal year and use that rate to provide for income taxes on a current year-to-date basis, as adjusted for discrete taxable events that occur during the interim period. Our effective tax rate for the three and nine months ended September 30, 2018 was 20.7% and 30.0%, respectively. Our effective tax rate for the three and nine months ended September 30, 2017 was 34.2% and 39.3%, respectively. For the three months ended September 30, 2018, the effective tax rate was lower than the federal statutory rate primarily due to a release of valuation allowances on certain foreign deferred tax assets. For the nine months ended September 30, 2018, the effective tax rate was greater than the federal statutory rate primarily due to other foreign valuation allowances and the income tax effects of the accounting for share-based compensation. The change in the effective tax rate for the three and nine months ended September 30, 2018 when compared to the same periods in 2017 was primarily due to the rate reduction from the enactment of the U.S. Tax Cuts and Jobs Act of 2017 (“2017 Tax Act”), as discussed below. The 2017 Tax Act introduced significant changes to U.S. income tax law. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and a one-time tax on the mandatory deemed repatriation of cumulative foreign earnings (the “Transition Tax”) as of December 31, 2017. On December 22, 2017, the SEC issued Staff Accounting Bulletin No. 118, or SAB 118, which allows us to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. The measurement period is deemed to have ended earlier when the registrant has obtained, prepared, and analyzed the information necessary to finalize its accounting. During the measurement period, impacts of the law are expected to be recorded at the time a reasonable estimate for all or a portion of the effects can be made, and provisional amounts can be recognized and adjusted as information becomes available, prepared, or analyzed. During both the three and nine months ended September 30, 2018, we recorded a $2 million income tax expense related to the Transition Tax, which reflects additional information that we obtained during 2018 related to uncertain tax positions, earnings and profits, foreign tax credits, and state taxes. Additional work is still necessary for a more detailed analysis of our historical foreign earnings. Any subsequent adjustment to these amounts will be recorded to current tax expense in the fourth quarter of 2018 when the analysis is complete. In addition, as of September 30, 2018, we reclassified our 2017 federal tax return overpayment of $25 million from income taxes receivable to other long-term liabilities, as pursuant to Internal Revenue Service (“IRS”) guidance, this overpayment will be applied first toward the Transition Tax, which is payable over eight years. The remaining unpaid Transition Tax of $31 million is included in other long-term liabilities on our condensed unaudited consolidated balance sheet as of September 30, 2018. We are subject to additional requirements of the 2017 Tax Act during the year ended December 31, 2018. Those provisions include a tax on global intangible low-taxed income (“GILTI”), a limitation of certain executive compensation, and a deduction for foreign derived intangible income (“FDII”). We have elected to account for GILTI as a period cost, and therefore included GILTI expense in the effective tax rate calculation. Our 2018 effective tax rate includes our estimates of these new provisions, with a net tax benefit of $3 million and $6 million recorded during the three and nine months ended September 30, 2018, respectively. Our estimates may be revised in future periods as we obtain additional data, and as the IRS issues new guidance implementing the law changes. Our policy is to recognize accrued interest and penalties related to unrecognized tax benefits and income tax liabilities as part of our income tax expense. As of September 30, 2018, accrued interest was $14 million, net of federal and state benefit, and no penalties have been accrued. By virtue of consolidated income tax returns previously filed with Expedia, we are currently under an IRS audit for the 2009, 2010 and short-period 2011 tax years, and have various ongoing audits for state income tax returns. We are separately under examination by the IRS for the short-period 2011, 2012 and 2013 tax years and under an employment tax audit by the IRS for the 2013 and 2014 tax years. These audits include questions about the timing and the amount of income and deductions and the allocation of income among various tax jurisdictions. These examinations may lead to proposed or ordinary course adjustments to our taxes. We are no longer subject to tax examinations by tax authorities for years prior to 2009. As of September 30, 2018, no material assessments have resulted, except as noted below regarding our 2009 and 2010 IRS audit with Expedia . In January 2017, as part of the IRS audit of Expedia, we received Notices of Proposed Adjustment from the IRS for the 2009 and 2010 tax years. These proposed adjustments are related to certain transfer pricing arrangements with our foreign subsidiaries, and would result in an increase to our worldwide income tax expense in an estimated range of $10 million to $14 million after consideration of competent authority relief, exclusive of interest and penalties. We disagree with the proposed adjustments and we intend to defend our position through applicable administrative and, if necessary, judicial remedies. Our policy is to review and update tax reserves as facts and circumstances change. Based on our interpretation of the regulations and available case law, we believe the position we have taken with regard to transfer pricing with our foreign subsidiaries is sustainable. In addition to the risk of additional tax for 2009 and 2010 transactions, if the IRS were to seek transfer pricing adjustments of a similar nature for transactions in subsequent years, we would be subject to significant additional tax liabilities. In July 2015, the United States Tax Court (the “Court”) issued an opinion favorable to Altera Corporation (“Altera”) with respect to Altera’s litigation with the IRS. This opinion was submitted as a final decision under Tax Court Rule 155 during December 2015. The litigation relates to the treatment of stock-based compensation expense in an inter-company cost-sharing arrangement with Altera’s foreign subsidiary. In its opinion, the Court accepted Altera’s position of excluding stock-based compensation from its inter-company cost-sharing arrangement. The IRS appealed the Court decision on February 19, 2016. At this time, the U.S. Department of the Treasury has not withdrawn the requirement from its regulations to include stock-based compensation in intercompany cost-sharing arrangements. The Company recorded an income tax benefit of $1 million and $2 million during the three and nine months ended September 30, 2018, respectively, and an income tax benefit of $2 million and $5 million for the three and nine months ended September 30, 2017, respectively, in its unaudited condensed consolidated statement of operations. Since the Court’s 2015 opinion, the Company has taken total income tax benefits of $15 million to date as of September 30, 2018. On July 24, 2018, the IRS won the appeals court case at the Ninth Circuit; however, on August 7, 2018, the Ninth Circuit withdrew its decision regarding Altera and the case will be reheard. While we have taken an income tax benefit based on the Court’s 2015 opinion, as discussed above, we will continue to review the latest decisions on the case and its impact to our consolidated financial statements.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 9: COMMITMENTS AND CONTINGENCIES There have been no material changes to our commitments and contingencies since December 31, 2017. Refer to “Note 13: Commitments and Contingencies Legal Proceedings In the ordinary course of business, we are parties to regulatory and legal matters arising out of our operations. These matters may involve claims involving patent and intellectual property rights (including alleged infringement of third-party intellectual property rights), tax matters (including value-added, excise, transient occupancy and accommodation taxes), regulatory compliance (including competition and consumer matters), defamation and other claims. Periodically, we review the status of all significant outstanding matters to assess any potential financial exposure. When (i) it is probable that an asset has been impaired or a liability has been incurred; and (ii) the amount of the loss can be reasonably estimated, we record the estimated loss in our consolidated statements of operations. We provide disclosures in the notes to the consolidated financial statements for loss contingencies that do not meet both of these conditions if there is a reasonable probability that a loss may have been incurred and whether such loss is reasonably estimable. We base accruals on the best information available at the time which can be highly subjective. Although occasional adverse decisions or settlements may occur, we do not believe that the final disposition of any of these matters will have a material adverse effect on our business. However, the final outcome of these matters could vary significantly from our estimates. Finally, there may be claims or actions pending or threatened against us of which we are currently not aware and the ultimate disposition of which could have a material adverse effect on us. Income Taxes We are under audit by the IRS and various other domestic and foreign tax authorities with regards to income tax matters. We have reserved for potential adjustments to our provision for income taxes that may result from examinations by, or any negotiated agreements with, these tax authorities. Although we believe our tax estimates are reasonable, the final determination of audits could be materially different from our historical income tax provisions and accruals. The results of an audit could have a material effect on our financial position, results of operations, or cash flows in the period for which that determination is made. We continue to accumulate cash flows, in foreign jurisdictions which we consider indefinitely reinvested, although we will continue to evaluate the impact of the 2017 Tax Act on our capital deployment within and outside the U.S. Any repatriation of funds currently held in foreign jurisdictions may result in withholding taxes and state taxes. Refer to “Note 8: Income Taxes

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Stockholders' Equity	NOTE 10: STOCKHOLDERS’ EQUITY On January 31, 2018, our Board of Directors authorized up to $250 million of share repurchases. Our Board of Directors authorized and directed management, working with the Executive Committee of our Board of Directors, to affect the share repurchase program in compliance with applicable legal requirements. This repurchase program has no expiration date but may be suspended or terminated by the Board of Directors at any time. During the three months ended September 30, 2018 we did not repurchase any shares of our common stock. During the nine months ended September 30, 2018, we repurchased 2,582,198 shares of our outstanding common stock under the share repurchase program at an aggregate cost of $100 million, or an average share price of $38.73 per share, exclusive of fees and commissions. As of September 30, 2018, we had a remaining balance of $150 million available to repurchase shares of our common stock under the share repurchase program.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	NOTE 11: RELATED PARTY TRANSACTIONS We consider Liberty TripAdvisor Holdings, Inc. (“LTRIP”) a related party. As of September 30, 2018, LTRIP beneficially owned approximately 18.2 million shares of our common stock and 12.8 million shares of our Class B common stock, which shares constitute 14.5% of the outstanding shares of common stock and 100% of the outstanding shares of Class B common stock. Assuming the conversion of all of LTRIP’s shares of Class B common stock into common stock, LTRIP would beneficially own 22.5% of the outstanding common stock. Because each share of Class B common stock is entitled to ten votes per share and each share of common stock is entitled to one vote per share, LTRIP may be deemed to beneficially own equity securities representing 57.8% of our voting power. We had no related party transactions with LTRIP during both the three and nine months ended September 30, 2018 and 2017.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment Information	NOTE 12: SEGMENT INFORMATION Our reporting structure includes two reportable segments: Hotel and Non-Hotel. Our Non-Hotel segment consists of the aggregation of three operating segments: Experiences, Restaurants and Rentals. The nature of the services provided are summarized in “Note 3: Revenue Recognition Our operating segments are determined based on how our chief operating decision maker manages our business, regularly assesses information and evaluates performance for operating decision-making purposes, including allocation of resources. The chief operating decision maker for the Company is our CEO. Adjusted EBITDA is our segment profit measure and a key measure used by our management and board of directors to understand and evaluate the operating performance of our business and on which internal budgets and forecasts are based and approved. In particular, the exclusion of certain expenses in calculating Adjusted EBITDA can provide a useful measure for period-to-period comparisons of our core business. The following tables present our segment information for the three and nine months ended September 30, 2018 and 2017 and include a reconciliation of Adjusted EBITDA to Net Income. We record depreciation of property and equipment, including amortization of internal-use software and website development, amortization of intangible assets, stock-based compensation and other stock-settled obligations, other income (expense), net, other non-recurring expenses and income, net, and income taxes, which are excluded from segment operating performance, in corporate and unallocated. In addition, we do not report our assets, capital expenditures and related depreciation expense by segment as our chief operating decision maker does not use this information to evaluate operating segments. Accordingly, we do not regularly provide such information by segment to our chief operating decision maker. Intersegment revenue is not material and, in addition, already eliminated in the information by segment provided to our chief operating decision maker. Our consolidated general and administrative expenses, excluding stock-based compensation costs, are shared by all operating segments. Each operating segment receives an allocated charge based on the segment’s percentage of the Company’s total personnel costs. Three months ended September 30, 2018 Hotel Non-Hotel Corporate and Unallocated Total (in millions) Revenue $ 305 $ 153 $ - $ 458 Adjusted EBITDA (1) 99 47 - 146 Depreciation (20 ) (20 ) Amortization of intangible assets (8 ) (8 ) Stock-based compensation (29 ) (29 ) Operating income (loss) 89 Other expense, net (2 ) Income before income taxes 87 Provision for income taxes (18 ) Net income $ 69 Three months ended September 30, 2017 Hotel Non-Hotel Corporate and Unallocated Total (in millions) Revenue $ 312 $ 127 $ - $ 439 Adjusted EBITDA (2) 51 44 - 95 Depreciation (19 ) (19 ) Amortization of intangible assets (8 ) (8 ) Stock-based compensation (26 ) (26 ) Operating income (loss) 42 Other expense, net (4 ) Income before income taxes 38 Provision for income taxes (13 ) Net income $ 25 Nine months ended September 30, 2018 Hotel Non-Hotel Corporate and Unallocated Total (in millions) Revenue $ 917 $ 352 $ - $ 1,269 Adjusted EBITDA (1) 276 59 - 335 Depreciation (61 ) (61 ) Amortization of intangible assets (24 ) (24 ) Stock-based compensation (90 ) (90 ) Operating income (loss) 160 Other expense, net (10 ) Income before income taxes 150 Provision for income taxes (45 ) Net income $ 105 Nine months ended September 30, 2017 Hotel Non-Hotel Corporate and Unallocated Total (in millions) Revenue $ 952 $ 283 $ - $ 1,235 Adjusted EBITDA (2) 223 46 - 269 Depreciation (57 ) (57 ) Amortization of intangible assets (25 ) (25 ) Stock-based compensation (72 ) (72 ) Operating income (loss) 115 Other expense, net (8 ) Income before income taxes 107 Provision for income taxes (42 ) Net income $ 65 (1) Includes allocated general and administrative expenses in our Hotel segment of $17 million and $57 million; and in our Non-Hotel segment of $12 million and $37 million for the three and nine months ended September 30, 2018, respectively. (2) Includes allocated general and administrative expenses in our Hotel segment of $22 million and $60 million; and in our Non-Hotel segment of $11 million and $30 million for the three and nine months ended September 30, 2017, respectively.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements present our results of operations, financial position and cash flows on a consolidated basis. The unaudited condensed consolidated financial statements include TripAdvisor, our wholly-owned subsidiaries, and entities we control, or in which we have a variable interest and are the primary beneficiary of expected cash profits or losses. All inter-company accounts and transactions have been eliminated in consolidation. One of our subsidiaries that operates in China has variable interests in affiliated entities in China in order to comply with Chinese laws and regulations, which restrict foreign investment in Internet content provision businesses. Although we do not own the capital stock of these Chinese affiliates, we consolidate their results as we are the primary beneficiary of the cash losses or profits of these variable interest affiliates and have the power to direct the activity of these affiliates. Our variable interest entities’ financials were not material for all periods presented. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) and include all normal and recurring adjustments that management of the Company considers necessary for a fair presentation of its financial position and operating results.
Accounting Estimates	Accounting Estimates We use estimates and assumptions in the preparation of our unaudited condensed consolidated financial statements in accordance with GAAP. Our estimates and assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of our unaudited condensed consolidated financial statements. These estimates and assumptions also affect the reported amount of net income or loss during any period. Our actual financial results could differ significantly from these estimates. The significant estimates underlying our unaudited condensed consolidated financial statements include: (i) recognition and recoverability of goodwill, definite-lived intangibles and other long-lived assets; and (ii) accounting for income taxes.
Seasonality	Seasonality Traveler expenditures in the global travel market tend to follow a seasonal pattern. As such, expenditures by travel partners/advertisers to market to potential travelers and, therefore our financial performance, or revenue and profits, tend to be seasonal as well. Our financial performance tends to be seasonally highest in the second and third quarters of a year, as it is a key period for leisure travel research and trip-taking, which includes the seasonal peak in traveler hotel and rental stays, and tours and experiences taken, compared to the first and fourth quarters which represent seasonal low points. Further significant shifts in our business mix or adverse economic conditions could result in future seasonal patterns that are different from historical trends.
New Accounting Pronouncements Not Yet Adopted and Recently Adopted Accounting Pronouncements	New Accounting Pronouncements Not Yet Adopted In August 2018, the SEC adopted a final rule under SEC Release No. 33-10532, Disclosure Update and Simplification This final rule is effective on November 5, 2018. As clarified by the SEC under Question 105.09 of the Exchange Act Forms C&DIs, which provides some relief to registrants that file Form 10-Q shortly after the final rule’s effective date, the Company will apply the disclosure change in stockholders’ equity analysis in its March 31, 2019, Form 10-Q. Additionally, the Company is in the process of evaluating the other disclosure impacts this final rule may have on its consolidated financial statement disclosures. In August 2018, the Financial Accounting Standards Board (“FASB”) issued new accounting guidance which require a customer in a cloud computing arrangement (i.e., hosting arrangement) that is a service contract to follow the internal-use software guidance to determine which implementation costs to capitalize as assets or expense as incurred. The accounting for the cost of the hosting component of the arrangement (i.e., service costs the customer pays for the cloud computing service) is not affected by this new guidance. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted, including adoption in any interim period. Entities have the option to apply the guidance retrospectively or prospectively to all implementation costs incurred after the date of adoption. We are currently considering our timing of adoption and the transition application method. We are also in the process of evaluating the impact of adopting this guidance on our consolidated financial statements and related disclosures. In June 2016, the FASB issued new accounting guidance on the measurement of credit losses for financial assets measured at amortized cost, which includes accounts receivable, and available-for-sale debt securities. For financial assets measured at amortized cost, this new guidance requires an entity to: (1) estimate its lifetime expected credit losses upon recognition of the financial assets and establish an allowance to present the net amount expected to be collected; (2) recognize this allowance and changes in the allowance during subsequent periods through net income; and (3) consider relevant information about past events, current conditions and reasonable and supportable forecasts in assessing the lifetime expected credit losses. For available-for-sale debt securities, this new guidance made several targeted amendments to the existing other-than-temporary impairment model, including: (1) requiring disclosure of the allowance for credit losses; (2) allowing reversals of the previously recognized credit losses until the entity has the intent to sell, is more-likely-than-not required to sell the securities or the maturity of the securities; (3) limiting impairment to the difference between the amortized cost basis and fair value; and (4) not allowing entities to consider the length of time that fair value has been less than amortized cost as a factor in evaluating whether a credit loss exists. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted, including interim periods within those fiscal years beginning after December 15, 2018. We are currently considering our timing of adoption and in the process of evaluating the impact of adopting this guidance on our consolidated financial statements and related disclosures. In February 2016, the FASB issued new guidance related to accounting for leases. The new standard requires the recognition of right-of-use (ROU) assets and lease liabilities on the balance sheet for all leases with a term longer than 12 months, which will initially be measured at the present value of the future lease payments over the lease term. For leases with a term of 12 months or less and that do not include an option to purchase the underlying asset or renew the lease term, that the lessee is reasonably certain to exercise, a lessee can make an accounting policy election by class of underlying asset to not recognize these leases on the balance sheet. Additionally, a lessee can also make an accounting policy election by class of underlying asset to not separate lease and non-lease components. Under the new guidance, leases will be classified as either finance or operating leases, with classification affecting the pattern and presentation of expenses and cash flows on our consolidated financial statements. The new guidance will require us to provide additional qualitative and quantitative disclosures regarding the amount, timing and uncertainty of cash flows arising from leases which include, among other things, the computation and disclosure of our weighted average remaining lease term and discount rate, cash paid for amounts included in the measurement of lease liabilities, and supplemental non-cash information on lease liabilities arising from obtaining the ROU assets. These disclosures are intended to provide supplemental information to the amounts recorded in the financial statements so that users can better understand the nature of an entity’s leasing activities. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. We will adopt the new standard on January 1, 2019 and use the effective date as our date of initial application based on the modified retrospective approach without adjusting the comparative periods presented. We expect to elect certain available practical expedients under the transition guidance at adoption. While we continue to assess all of the effects of adoption on our consolidated financial statements, including providing significant new disclosures about our leasing activities, we currently believe the primary effects of this new guidance relate to: (1) our existing operating leases for office space in which the new guidance requires us to recognize on our balance sheet the new ROU assets and lease liabilities; (2) our corporate headquarters lease, which is currently accounted for as a financing obligation, and of which we were deemed the owner for accounting purposes under the current build-to-suit lease guidance. The transition guidance for a build-to-suit lease arrangement requires the lessee to derecognize the assets and liabilities that were recognized solely as a result of a transaction’s build-to-suit designation under the current guidance, with any difference recorded as an adjustment to equity as of the adoption date. We will subsequently apply the general lessee guidance under the new standard to our corporate headquarters lease, including classifying it as either a finance or operating lease, and record a ROU asset and lease liability on the balance sheet, which will be initially measured at the present value of the remaining lease payments over the lease term. We are currently still assessing the quantitative impact this new guidance may have on our consolidated financial statements related to the aforementioned leases. We continue to update our accounting policies and accounting memos under the new guidance, and evaluate our existing population of contracts to ensure all contracts that meet the definition of a lease contract under the new standard are identified. We have completed the implementation of our lease accounting software to support our accounting process, financial reporting and the new additional quantitative and qualitative financial disclosure requirements and are now engaging in readiness activities during the fourth quarter for the January 1, 2019- go-live date. In addition, we are evaluating the impact of this new system implementation and new accounting guidance on our internal accounting process and controls. We will continue to provide updates on our assessment of the effect that this new lease guidance will have on our consolidated financial statements, disclosures, systems and related internal controls, and will disclose material effects, if any, when known. Recently Adopted Accounting Pronouncements In May 2017, the FASB issued new accounting guidance that clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications which will reduce diversity in practice. Under the new guidance, an entity will not apply modification accounting to a share-based payment award if the award’s fair value (or calculated value or intrinsic value, if those measurement methods are used), the award’s vesting conditions, and the award’s classification as an equity or liability instrument are the same immediately before and after the change. The guidance also states that an entity is not required to estimate the value of the award immediately before and after the change if the change does not affect any of the inputs to the model used to value the award. We adopted this guidance prospectively in the first quarter of 2018. We believe the new guidance will likely result in fewer changes to the terms of an award being accounted for as modifications. In January 2017, the FASB issued new accounting guidance to clarify the definition of a business and provide additional guidance to assist entities with evaluating whether transactions should be accounted for as asset acquisitions (or asset disposals) or business combinations (or disposals of a business). Under this new guidance, an entity first determines whether substantially all of the fair value of the assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. If this criterion is met, the transaction should be accounted for as an asset acquisition as opposed to a business combination. This distinction is important because the accounting for an asset acquisition significantly differs from the accounting for a business combination. This new guidance eliminates the requirement to evaluate whether a market participant could replace missing elements (e.g. inputs or processes), narrows the definition of outputs and requires that a business include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. We adopted this guidance in the first quarter of 2018 and it will be applied prospectively to any transactions occurring within and after the adoption date. In November 2016, the FASB issued new accounting guidance on the classification and presentation of restricted cash in the statement of cash flows to address the diversity in practice. This new guidance requires entities to show changes in cash, cash equivalents and restricted cash on a combined basis in the statement of cash flows. In addition, this accounting guidance requires a reconciliation of the total cash, cash equivalent and restricted cash in the statement of cash flows to the related captions in the balance sheet if cash, cash equivalents and restricted cash are presented in more than one line item in the balance sheet. We adopted this guidance in the first quarter of 2018 and applied it retrospectively to all prior periods presented in the financial statements as required under the new guidance. The adoption did not have a material impact on our consolidated financial statements and related disclosures. In October 2016, the FASB issued new accounting guidance on income tax accounting associated with intra-entity transfers of assets other than inventory. This accounting update, which is part of the FASB's simplification initiative, is intended to reduce diversity in practice and the complexity of tax accounting, particularly for those transfers involving intellectual property. This new guidance requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. We adopted this new guidance in the first quarter of 2018 on a modified retrospective basis. Accordingly, we recognized the cumulative effect of initial application of this new guidance as an adjustment to the opening balance of retained earnings, which was not material to our consolidated financial statements. In August 2016, the FASB issued new accounting guidance which clarifies how companies present and classify certain cash receipts and cash payments in the statement of cash flows. The new guidance specifically addresses the following cash flow topics in an effort to reduce diversity in practice: (1) debt prepayment or debt extinguishment costs; (2) settlement of zero-coupon bonds; (3) contingent consideration payments made after a business combination; (4) proceeds from the settlement of insurance claims; (5) proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; (6) distributions received from equity method investees; (7) beneficial interests in securitization transactions; and (8) separately identifiable cash flows and application of the predominance principle. We adopted this new guidance in the first quarter of 2018 retrospectively and the adoption did not have an impact on our consolidated financial statements and related disclosures. In January 2016, the FASB issued new accounting guidance which amends the standard on the recognition and measurement of financial instruments. The FASB clarified certain aspects of this guidance by issuing an update for technical corrections and improvements related to this guidance in February 2018. The guidance (1) requires an entity to measure equity investments (except those accounted for under the equity method or those that result in consolidation of the investee) at fair value with changes in fair value recognized in net income rather than accumulated other comprehensive income on the balance sheet; (2) allows an entity to elect to measure the equity investments that do not have a readily determinable fair value using a new measurement alternative which measure these equity investments at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer; (3) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; and (4) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity’s evaluation of their other deferred tax assets. We adopted this guidance in the first quarter of 2018 and elected to prospectively account for our investments in equity securities of privately-held companies that do not have a readily determinable fair value using In May 2014, the FASB issued new accounting guidance on revenue from contracts with customers, or ASC 606, Revenue from Contracts with Customers In the first quarter of 2018, we adopted ASC 606 under the modified retrospective method for all contracts that were not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under the new revenue guidance, while prior period amounts are not adjusted and continue to be reported in accordance with our previous accounting policies under the historical revenue guidance, or ASC 605, Revenue Recognition We evaluated each of our revenue streams and applied ASC 606 as further discussed in “Note 3: Revenue Recognition for the commission We recognized the cumulative effect of initial application of ASC 606 as an adjustment to the opening balance of retained earnings. We recorded a net increase in opening retained earnings of $4 million as of January 1, 2018 due to the cumulative impact of adoption of the new revenue guidance and all other accounts were not materially impacted. There have been no changes to our significant accounting policies since December 31, 2017, other than noted above. See “Note 3: Revenue Recognition Significant Accounting Policies

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2018
Reconciliation of Disaggregated Revenue to Segment Revenue	A reconciliation of disaggregated revenue to segment revenue is also included below. Three months ended September 30, 2018 Nine months ended September 30, 2018 Major products/revenue sources: (in millions) TripAdvisor-branded click-based advertising and transaction revenue $ 194 $ 583 TripAdvisor-branded display-based advertising and subscription revenue 81 231 Other hotel revenue 30 103 Total Hotel Revenue (1) 305 917 Non-Hotel Revenue (1) 153 352 Total Revenue $ 458 $ 1,269 (1) Our revenue is recognized primarily at a point in time for both our Hotel and Non-Hotel segments.
Summary of Balances of Accounts Receivables and Contract Assets from Contracts with Customers	The following table provides information about the opening and closing balances of accounts receivables and contract assets from contracts with customers (in millions): September 30, 2018 December 31, 2017 Accounts receivable 227 230 Contract assets 10 - Total $ 237 $ 230
ASC 606
Summary of Impact of New Revenue Recognition Guidance on Unaudited Condensed Consolidated Statement of Operations	The impact of this new revenue recognition guidance on our unaudited condensed consolidated statement of operations for the three and nine months ended September 30, 2018 was as follows: Three months ended September 30, 2018 INCOME STATEMENT As Reported - ASC 606 September 30, 2018 Impact of Accounting ASC 606 Adjusted - ASC 605 September 30, 2018 (in millions, except per share amounts) Revenue $ 458 $ 3 $ 461 Operating income 89 3 92 Income before income taxes 87 3 90 Provision for income taxes (18 ) - (18 ) Net income 69 3 72 Basic EPS 0.50 0.02 0.52 Diluted EPS 0.49 0.02 0.51 Nine months ended September 30, 2018 INCOME STATEMENT As Reported - ASC 606 September 30, 2018 Impact of Accounting ASC 606 Adjusted - ASC 605 September 30, 2018 (in millions, except per share amounts) Revenue $ 1,269 $ (3 ) $ 1,266 Operating income 160 (3 ) 157 Income before income taxes 150 (3 ) 147 Provision for income taxes (45 ) 1 (44 ) Net income 105 (2 ) 103 Basic EPS 0.76 (0.01 ) 0.75 Diluted EPS 0.75 (0.01 ) 0.74

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Reconciliation of Weighted Average Number of Shares of Common Stock Outstanding	Below is a reconciliation of the weighted average number of shares of common stock outstanding in calculating Diluted EPS (shares in thousands and dollars in millions, except per share amounts) for the periods presented: Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Numerator: Net income $ 69 $ 25 $ 105 $ 65 Denominator: Weighted average shares used to compute Basic EPS 137,574 138,779 138,239 140,961 Weighted average effect of dilutive securities: Stock options 518 193 305 312 RSUs/MSUs 2,421 416 1,607 408 Weighted average shares used to compute Diluted EPS 140,513 139,388 140,151 141,681 Basic EPS $ 0.50 $ 0.18 $ 0.76 $ 0.46 Diluted EPS $ 0.49 $ 0.18 $ 0.75 $ 0.46

Stock Based Awards and Other _2

Stock Based Awards and Other Equity Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Amount of Stock-Based Compensation Expense Related to Stock-Based Awards, Primarily Stock Options and RSUs	The following table presents the amount of stock-based compensation expense related to stock-based awards, primarily stock options and RSUs, on our unaudited condensed consolidated statements of operations during the periods presented: Three months ended Nine months ended September 30, September 30, 2018 2017 2018 2017 (in millions) (in millions) Selling and marketing $ 5 $ 5 $ 17 $ 16 Technology and content 13 12 38 31 General and administrative 11 9 35 25 Total stock-based compensation 29 26 90 72 Income tax benefit from stock-based compensation (7 ) (9 ) (22 ) (27 ) Total stock-based compensation, net of tax effect $ 22 $ 17 $ 68 $ 45
Summary of Stock Option Activity	A summary of our stock option activity during the nine months ended September 30, 2018, is presented below: Weighted Weighted Average Average Exercise Remaining Aggregate Options Price Per Contractual Intrinsic Outstanding Share Life Value (in thousands) (in years) (in millions) Options outstanding at December 31, 2017 6,853 $ 52.78 Granted 632 41.87 Exercised (1) (619 ) 36.46 Cancelled or expired (266 ) 51.93 Options outstanding at September 30, 2018 6,600 $ 53.29 6.3 $ 44 Exercisable as of September 30, 2018 3,764 $ 58.79 4.5 $ 19 Vested and expected to vest after September 30, 2018 (2) 6,600 $ 53.29 6.3 $ 44 (1) Inclusive of 458,413 options which were not converted into shares due to net share settlement in order to cover the aggregate exercise price and the required amount of employee withholding taxes. Potential shares that had been convertible under stock options that were withheld under net share settlement remain in the authorized but unissued pool under the 2018 Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows. (2) The Company accounts for forfeitures as they occur, rather than estimate expected forfeitures as allowed under GAAP and therefore do not include a forfeiture rate in our vested and expected to vest calculation unless necessary for a performance condition award.
Weighted-Average Assumptions of Estimated Fair Value of Stock Option Grants	The fair value of stock option grants has been estimated at the date of grant using the Black–Scholes option pricing model with the following weighted average assumptions for the periods presented: Three months ended Nine months ended September 30, September 30, 2018 2017 2018 2017 Risk free interest rate 2.78 % 1.84 % 2.66 % 1.90 % Expected term (in years) 5.45 5.32 5.45 5.35 Expected volatility 40.22 % 41.31 % 42.26 % 41.52 % Expected dividend yield — % — % — % — %
Summary of RSU Activity, Including Service Based Awards and Performance-Based Awards	Weighted Average Grant- Aggregate RSUs Date Fair Intrinsic Outstanding Value Per Share Value (in thousands) (in millions) Unvested RSUs outstanding as of December 31, 2017 (1) 6,015 $ 48.14 Transfer (1) (213 ) 30.04 Granted 3,263 42.19 Vested and released (2) (1,454 ) 53.38 Cancelled (715 ) 46.51 Unvested RSUs outstanding as of September 30, 2018 6,896 $ 44.95 $ 352 Expected to vest after September 30, 2018 (3) 6,896 $ 44.95 $ 352 (1) RSUs outstanding as of December 31, 2017 include 213,000 market-based restricted stock units (“MSUs”) awarded to the Company’s CEO in November 2017. This award has been transferred to the MSU activity table below. (2) Inclusive of 378,235 RSUs withheld due to net share settlement to satisfy required employee tax withholding requirements. Potential shares which had been convertible under RSUs that were withheld under net share settlement remain in the authorized but unissued pool under the 2018 Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows. (3) The Company accounts for forfeitures as they occur, rather than estimate expected forfeitures as allowed under GAAP and therefore do not include a forfeiture rate in our expected to vest calculation unless necessary for a performance condition award.
Summary of Unrecognized Stock-Based Compensation Expense and Weighted Average Period Remaining	A summary of our remaining unrecognized stock-based compensation expense and the weighted average remaining amortization period at September 30, 2018 related to our non-vested equity awards is presented below (in millions, except in years information): Stock Options RSUs MSUs Unrecognized compensation expense $ 39 $ 245 $ 8 Weighted average period remaining (in years) 3.0 2.8 2.3
MSUs
Summary of RSU Activity, Including Service Based Awards and Performance-Based Awards	A summary of our RSU activity for MSUs, during the nine months ended September 30, 2018 is presented below: Weighted Average Grant- Aggregate MSUs Date Fair Intrinsic Outstanding Value Per Share Value (in thousands) (in millions) Unvested MSUs outstanding as of December 31, 2017 (1) 213 $ 30.04 Granted (2) 71 59.40 Vested and released ― ― Cancelled ― ― Unvested MSUs outstanding as of September 30, 2018 284 $ 37.41 $ 15 ( 1) Represents 213,000 MSUs awarded to the Company’s CEO in November 2017. (2) MSUs provide for vesting based upon the Company’s total shareholder return, or TSR, performance over the period commencing January 1, 2018 through December 31, 2020 relative to the TSR performance of the Nasdaq Composite Total Return Index. A Monte-Carlo simulation model, which simulated the present value of the potential outcomes of future stock prices and TSR of the Company and the Nasdaq Composite Total Return Index over the performance period, was used to calculate the grant-date fair value of these awards. The estimated grant-date fair value of these awards is being amortized on a straight-line basis over the requisite service period through December 31, 2020. Based upon actual attainment relative to the target performance metric, the grantee has the ability to receive up to 200% of the target number of MSUs originally granted, or to be issued none at all. These MSUs were granted under the 2011 Plan.

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments All Other Investments [Abstract]
Schedule of Cash, Cash Equivalents, Restricted Cash and Marketable Securities	The following tables show our cash, cash equivalents, restricted cash and short-term and long-term available-for-sale marketable debt securities, by major security type, that are measured at fair value on a recurring basis and were categorized using the fair value hierarchy, as well as their classification on September 30, 2018 Amortized Cost Fair Value (2) Cash, Cash Equivalents and Restricted Cash Short-Term Marketable Securities Long-Term Marketable Securities (3) Cash and restricted cash (1) $ 421 $ 421 $ 421 $ - $ - Level 1: Money market funds 242 242 242 - - Total $ 663 $ 663 $ 663 $ - $ - December 31, 2017 Amortized Cost Fair Value (2) Cash, Cash Equivalents and Restricted Cash Short-Term Marketable Securities Long-Term Marketable Securities (3) Cash and restricted cash (1) $ 663 $ 663 $ 663 $ - $ - Level 1: Money market funds 1 1 1 - - Level 2: U.S. agency securities 11 11 - 6 5 U.S. treasury securities 1 1 - 1 - Certificates of deposit 2 2 - 2 - Commercial paper 11 11 9 2 - Corporate debt securities 46 46 - 24 22 Subtotal 71 71 9 35 27 Total $ 735 $ 735 $ 673 $ 35 $ 27 (1) As of September 30, 2018 and December 31, 2017, our restricted cash, which primarily consists of escrowed security deposits, was not material and is included in other long-term assets on our unaudited condensed consolidated balance sheets. (2) As of September 30, 2018 and December 31, 2017, any unrealized gains or losses related to our marketable securities were not material. (3) Long-term marketable securities are included in other long-term assets on our unaudited condensed consolidated balance sheets.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Summary of Segment Information	Three months ended September 30, 2018 Hotel Non-Hotel Corporate and Unallocated Total (in millions) Revenue $ 305 $ 153 $ - $ 458 Adjusted EBITDA (1) 99 47 - 146 Depreciation (20 ) (20 ) Amortization of intangible assets (8 ) (8 ) Stock-based compensation (29 ) (29 ) Operating income (loss) 89 Other expense, net (2 ) Income before income taxes 87 Provision for income taxes (18 ) Net income $ 69 Three months ended September 30, 2017 Hotel Non-Hotel Corporate and Unallocated Total (in millions) Revenue $ 312 $ 127 $ - $ 439 Adjusted EBITDA (2) 51 44 - 95 Depreciation (19 ) (19 ) Amortization of intangible assets (8 ) (8 ) Stock-based compensation (26 ) (26 ) Operating income (loss) 42 Other expense, net (4 ) Income before income taxes 38 Provision for income taxes (13 ) Net income $ 25 Nine months ended September 30, 2018 Hotel Non-Hotel Corporate and Unallocated Total (in millions) Revenue $ 917 $ 352 $ - $ 1,269 Adjusted EBITDA (1) 276 59 - 335 Depreciation (61 ) (61 ) Amortization of intangible assets (24 ) (24 ) Stock-based compensation (90 ) (90 ) Operating income (loss) 160 Other expense, net (10 ) Income before income taxes 150 Provision for income taxes (45 ) Net income $ 105 Nine months ended September 30, 2017 Hotel Non-Hotel Corporate and Unallocated Total (in millions) Revenue $ 952 $ 283 $ - $ 1,235 Adjusted EBITDA (2) 223 46 - 269 Depreciation (57 ) (57 ) Amortization of intangible assets (25 ) (25 ) Stock-based compensation (72 ) (72 ) Operating income (loss) 115 Other expense, net (8 ) Income before income taxes 107 Provision for income taxes (42 ) Net income $ 65 (1) Includes allocated general and administrative expenses in our Hotel segment of $17 million and $57 million; and in our Non-Hotel segment of $12 million and $37 million for the three and nine months ended September 30, 2018, respectively. (2) Includes allocated general and administrative expenses in our Hotel segment of $22 million and $60 million; and in our Non-Hotel segment of $11 million and $30 million for the three and nine months ended September 30, 2017, respectively.

Business Description and Basi_2

Business Description and Basis of Presentation - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018MarketLanguageBrandSegment
Description Of Business And Basis Of Presentation [Line Items]
Number of markets with localized versions of website | Market	48
Number of languages worldwide | Language	28
Number of reportable segment | Segment	2
Minimum
Description Of Business And Basis Of Presentation [Line Items]
Number of other media brands with websites | Brand	20

Significant Accounting Polici_3

Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions	Jan. 01, 2018	Sep. 30, 2018
Schedule Of Accounting Policies [Line Items]
Recorded a net increase in opening retained earnings		$ 4
ASC 606
Schedule Of Accounting Policies [Line Items]
Recorded a net increase in opening retained earnings	$ 4

Revenue Recognition - Additiona

Revenue Recognition - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)Segment	Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)
Disaggregation Of Revenue [Line Items]
Number of reportable segment | Segment		2
Deferred revenue	$ 73	$ 73	$ 59	$ 60
Revenue recognized	$ 8	$ 53
Maximum
Disaggregation Of Revenue [Line Items]
Capitalized contract cost, Amortization period	1 year	1 year
Sales Incentive Program | Minimum
Disaggregation Of Revenue [Line Items]
Capitalized contract cost, Amortization period	1 year	1 year
ASC 606
Disaggregation Of Revenue [Line Items]
Customer invoices due period		30 days
Capitalized costs to obtain a contract	$ 1	$ 1
Transaction price related to unsatisfied performance obligations expected period	1 year	1 year

Revenue Recognition - Summary o

Revenue Recognition - Summary of Impact of New Revenue Recognition Guidance on Unaudited Condensed Consolidated Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue (Note 3)	$ 458	$ 439	$ 1,269	$ 1,235
Operating income	89	42	160	115
Income before income taxes	87	38	150	107
Provision for income taxes	(18)	(13)	(45)	(42)
Net income	$ 69	$ 25	$ 105	$ 65
Basic EPS	$ 0.50	$ 0.18	$ 0.76	$ 0.46
Diluted EPS	$ 0.49	$ 0.18	$ 0.75	$ 0.46
Impact of Accounting ASC 606
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue (Note 3)	$ 3		$ (3)
Operating income	3		(3)
Income before income taxes	3		(3)
Provision for income taxes			1
Net income	$ 3		$ (2)
Basic EPS	$ 0.02		$ (0.01)
Diluted EPS	$ 0.02		$ (0.01)
Adjusted - ASC 605
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue (Note 3)	$ 461		$ 1,266
Operating income	92		157
Income before income taxes	90		147
Provision for income taxes	(18)		(44)
Net income	$ 72		$ 103
Basic EPS	$ 0.52		$ 0.75
Diluted EPS	$ 0.51		$ 0.74
ASC 606
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue (Note 3)	$ 458		$ 1,269
Operating income	89		160
Income before income taxes	87		150
Provision for income taxes	(18)		(45)
Net income	$ 69		$ 105
Basic EPS	$ 0.50		$ 0.76
Diluted EPS	$ 0.49		$ 0.75

Revenue Recognition - Reconcili

Revenue Recognition - Reconciliation of Disaggregated Revenue to Segment Revenue (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Total Revenue		$ 458	$ 439	$ 1,269	$ 1,235
Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue	[1]	305		917
Non-Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue	[1]	153		352
TripAdvisor-Branded Click-Based and Transaction Revenue | Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue		194		583
TripAdvisor-Branded Display-Based Advertising and Subscription Revenue | Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue		81		231
Other Hotel Revenue | Hotel Segment
Disaggregation Of Revenue [Line Items]
Total Revenue		$ 30		$ 103
[1]	Our revenue is recognized primarily at a point in time for both our Hotel and Non-Hotel segments.

Revenue Recognition - Summary_2

Revenue Recognition - Summary of Balances of Accounts Receivables and Contract Assets from Contracts with Customers (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Revenue From Contract With Customer [Abstract]
Accounts receivable	$ 227	$ 230
Contract assets	10
Total	$ 237	$ 230

Earnings Per Share - Reconcilia

Earnings Per Share - Reconciliation of Weighted Average Number of Shares of Common Stock Outstanding In Calculating EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income	$ 69	$ 25	$ 105	$ 65
Denominator:
Weighted average shares used to compute Basic EPS	137,574	138,779	138,239	140,961
Weighted average effect of dilutive securities:
Stock options	518	193	305	312
RSUs/MSUs	2,421	416	1,607	408
Weighted average shares used to compute Diluted EPS	140,513	139,388	140,151	141,681
Basic EPS	$ 0.50	$ 0.18	$ 0.76	$ 0.46
Diluted EPS	$ 0.49	$ 0.18	$ 0.75	$ 0.46

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Details) - Stock Options and RSUs - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3.4	6.4	7.1	6.6
Performance Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	0.5	0.1	0.5	0.1

Stock Based Awards and Other _3

Stock Based Awards and Other Equity Instruments - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jun. 21, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Capitalized stock based compensation as internal-use software and website development costs	$ 3	$ 3	$ 10	$ 10
Cash received from stock option exercises			3	3
Income tax benefits from exercise or settlement of stock-based awards	$ 1	$ 1	$ 10	17
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock options issued			632,114
Term of stock options, granted			10 years
Stock awards vest period			4 years
RSU
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock awards vest period			4 years
RSU's issued under incentive plan			3,263,455
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved and available for issuance					6,000,000
2011 Plan | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Closing stock price	$ 51.07		$ 51.07
Total intrinsic value			$ 7	$ 8
Weighted-average grant date fair value of options granted	$ 23.12	$ 15.49	$ 17.72	$ 17.16
Total fair value of stock options vested			$ 35	$ 39
Cash received from stock option exercises			$ 3	$ 3

Stock Based Awards and Other _4

Stock Based Awards and Other Equity Instruments - Amount of Stock-Based Compensation Expense Related to Stock-Based Awards, Primarily Stock Options and RSUs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 29	$ 26	$ 90	$ 72
Income tax benefit from stock-based compensation	(7)	(9)	(22)	(27)
Total stock-based compensation, net of tax effect	22	17	68	45
Selling and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	5	5	17	16
Technology and Content
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	13	12	38	31
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 11	$ 9	$ 35	$ 25

Stock Based Awards and Other _5

Stock Based Awards and Other Equity Instruments - Summary of Stock Option Activity (Details) - Stock Options $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)$ / sharesshares
Options Outstanding
Options Outstanding, Beginning balance | shares	6,853,000
Options Outstanding, Granted | shares	632,114
Options Outstanding, Exercised | shares	(619,000)	[1]
Options Outstanding, Cancelled or expired | shares	(266,000)
Options Outstanding, Ending balance | shares	6,600,000
Options Outstanding, Exercisable | shares	3,764,000
Options Outstanding, Vested and expected to vest | shares	6,600,000	[2]
Weighted Average Exercise Price per share
Options Outstanding, Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 52.78
Options Granted, Weighted Average Exercise Price | $ / shares	41.87
Options Exercised, Weighted Average Exercise Price | $ / shares	36.46	[1]
Options Cancelled or expired, Weighted Average Exercise Price | $ / shares	51.93
Options Outstanding, Weighted Average Exercise Price, Ending balance | $ / shares	53.29
Options Exercisable, Weighted Average Exercise Price | $ / shares	58.79
Options Vested and expected to vest, Weighted Average Exercise Price | $ / shares	$ 53.29	[2]
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 3 months 18 days
Options Exercisable, Weighted Average Remaining Contractual Life	4 years 6 months
Options Vested and expected to vest, Weighted Average Remaining Contractual Life	6 years 3 months 18 days	[2]
Options Outstanding, Aggregate Intrinsic Value | $	$ 44
Options Exercisable, Aggregate Intrinsic Value | $	19
Options Vested and expected to vest, Aggregate Intrinsic Value | $	$ 44	[2]
[1]	Inclusive of 458,413 options which were not converted into shares due to net share settlement in order to cover the aggregate exercise price and the required amount of employee withholding taxes. Potential shares that had been convertible under stock options that were withheld under net share settlement remain in the authorized but unissued pool under the 2018 Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows.
[2]	The Company accounts for forfeitures as they occur, rather than estimate expected forfeitures as allowed under GAAP and therefore do not include a forfeiture rate in our vested and expected to vest calculation unless necessary for a performance condition award.

Stock Based Awards and Other _6

Stock Based Awards and Other Equity Instruments - Summary of Stock Option Activity (Parenthetical) (Details)	9 Months Ended
	Sep. 30, 2018shares
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options non converted into shares due to net share settlement	458,413

Stock Based Awards and Other _7

Stock Based Awards and Other Equity Instruments - Weighted-Average Assumptions of Estimated Fair Value of Stock Option Grants (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk free interest rate	2.78%	1.84%	2.66%	1.90%
Expected term (in years)	5 years 5 months 12 days	5 years 3 months 25 days	5 years 5 months 12 days	5 years 4 months 6 days
Expected volatility	40.22%	41.31%	42.26%	41.52%

Stock Based Awards and Other _8

Stock Based Awards and Other Equity Instruments - Summary of RSU Activity, Including Service Based Awards and Performance-Based Awards (Details) - Restricted Stock Units $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)$ / sharesshares
RSUs outstanding
Unvested outstanding, Beginning balance | shares	6,015,000
Unvested RSUs, Transfer | shares	(213,000)	[1]
Unvested RSUs, Granted | shares	3,263,455
Unvested RSUs, Vested and released | shares	(1,454,000)	[2]
Unvested RSUs, Cancelled | shares	(715,000)
Unvested outstanding, Ending balance | shares	6,896,000
RSUs outstanding, Expected to vest | shares	6,896,000	[3]
Weighted Average Grant-Date Fair Value Per Share
Unvested outstanding, Weighted Average Grant-Date Fair Value Per Share, Beginning balance | $ / shares	$ 48.14
Weighted Average Grant-Date Fair Value Per Share, Transfer | $ / shares	30.04	[1]
Weighted Average Grant-Date Fair Value Per Share, Granted | $ / shares	42.19
Weighted Average Grant-Date Fair Value Per Share, Vested and released | $ / shares	53.38	[2]
Weighted Average Grant-Date Fair Value Per Share, Cancelled | $ / shares	46.51
Unvested outstanding, Weighted Average Grant-Date Fair Value Per Share, Ending balance | $ / shares	44.95
Weighted Average Grant-Date Fair Value Per Share, Expected to vest | $ / shares	$ 44.95	[3]
Aggregate Intrinsic Value
Unvested RSUs outstanding, Aggregate Intrinsic Value | $	$ 352
RSUs Vested and expected to vest, Aggregate Intrinsic Value | $	$ 352
[1]	RSUs outstanding as of December 31, 2017 include 213,000 market-based restricted stock units (“MSUs”) awarded to the Company’s CEO in November 2017. This award has been transferred to the MSU activity table below.
[2]	Inclusive of 378,235 RSUs withheld due to net share settlement to satisfy required employee tax withholding requirements. Potential shares which had been convertible under RSUs that were withheld under net share settlement remain in the authorized but unissued pool under the 2018 Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows.
[3]	The Company accounts for forfeitures as they occur, rather than estimate expected forfeitures as allowed under GAAP and therefore do not include a forfeiture rate in our expected to vest calculation unless necessary for a performance condition award.

Stock Based Awards and Other _9

Stock Based Awards and Other Equity Instruments - Summary of RSU Activity, Including Service Based Awards and Performance-Based Awards (Parenthetical) (Details) - Restricted Stock Units - shares		1 Months Ended	9 Months Ended
		Nov. 30, 2017	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share transfer award	[1]		213,000
RSUs withheld to satisfy withholding tax requirements			378,235
CEO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share transfer award		213,000
[1]	RSUs outstanding as of December 31, 2017 include 213,000 market-based restricted stock units (“MSUs”) awarded to the Company’s CEO in November 2017. This award has been transferred to the MSU activity table below.

Stock Based Awards and Other_10

Stock Based Awards and Other Equity Instruments - Summary of RSU Activity For MSUs (Details) - MSUs $ / shares in Units, shares in Thousands, $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)$ / sharesshares
MSUs outstanding
Unvested outstanding, Beginning balance | shares	213	[1]
Unvested MSUs, Granted | shares	71	[2]
Unvested outstanding, Ending balance | shares	284
Weighted Average Grant-Date Fair Value Per Share
Unvested outstanding, Weighted Average Grant-Date Fair Value Per Share, Beginning balance | $ / shares	$ 30.04	[1]
Weighted Average Grant-Date Fair Value Per Share, Granted | $ / shares	59.40	[2]
Unvested outstanding, Weighted Average Grant-Date Fair Value Per Share, Ending balance | $ / shares	$ 37.41
Aggregate Intrinsic Value
Unvested MSUs outstanding, Aggregate Intrinsic Value | $	$ 15
[1]	Represents 213,000 MSUs awarded to the Company’s CEO in November 2017.
[2]	MSUs provide for vesting based upon the Company’s total shareholder return, or TSR, performance over the period commencing January 1, 2018 through December 31, 2020 relative to the TSR performance of the Nasdaq Composite Total Return Index. A Monte-Carlo simulation model, which simulated the present value of the potential outcomes of future stock prices and TSR of the Company and the Nasdaq Composite Total Return Index over the performance period, was used to calculate the grant-date fair value of these awards. The estimated grant-date fair value of these awards is being amortized on a straight-line basis over the requisite service period through December 31, 2020. Based upon actual attainment relative to the target performance metric, the grantee has the ability to receive up to 200% of the target number of MSUs originally granted, or to be issued none at all. These MSUs were granted under the 2011 Plan.

Stock Based Awards and Other_11

Stock Based Awards and Other Equity Instruments - Summary of RSU Activity For MSUs (Parenthetical) (Details) - MSUs - shares	1 Months Ended	9 Months Ended
	Nov. 30, 2017	Sep. 30, 2018
Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of originally granted shares that may be earned upon performance achievement, maximum		200.00%
Percentage of originally granted shares that may be earned upon performance achievement, minimum		0.00%
Requisite service period for estimated grant-date fair value of stock awards		Dec. 31, 2020
Stock awards vesting term		MSUs provide for vesting based upon the Company’s total shareholder return, or TSR, performance over the period commencing January 1, 2018 through December 31, 2020 relative to the TSR performance of the Nasdaq Composite Total Return Index.
Performance measurement period start date		Jan. 1, 2018
Performance measurement period end date		Dec. 31, 2020
CEO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share transfer award	213,000

Stock Based Awards and Other_12

Stock Based Awards and Other Equity Instruments -Summary of Unrecognized Stock-Based Compensation Expense and Weighted Average Period Remaining (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense	$ 39
Weighted average period remaining (in years)	3 years
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average period remaining (in years)	2 years 9 months 18 days
Unrecognized compensation expense	$ 245
MSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average period remaining (in years)	2 years 3 months 18 days
Unrecognized compensation expense	$ 8

Financial Instruments - Schedul

Financial Instruments - Schedule of Cash, Cash Equivalents, Restricted Cash and Marketable Securities (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and Cash Equivalents		$ 663	$ 673
Short-Term Marketable Securities			35
Long-Term Marketable Securities	[1]		27
Cash	[2],[3]	421	663
Cash equivalents	[3]	421	663
Cash, cash equivalents, restricted cash and marketable securities, amortized cost		663	735
Cash, cash equivalents, restricted cash and marketable securities, fair value	[2]	663	735
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		$ 242	1
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost			71
Fair Value	[2]		71
Cash and Cash Equivalents			9
Short-Term Marketable Securities			35
Long-Term Marketable Securities	[1]		27
Level 2 | U.S. Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost			11
Fair Value	[2]		11
Short-Term Marketable Securities			6
Long-Term Marketable Securities	[1]		5
Level 2 | US treasury securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost			1
Fair Value	[2]		1
Short-Term Marketable Securities			1
Level 2 | Certificates of Deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost			2
Fair Value	[2]		2
Short-Term Marketable Securities			2
Level 2 | Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost			11
Fair Value	[2]		11
Cash and Cash Equivalents			9
Short-Term Marketable Securities			2
Level 2 | Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost			46
Fair Value	[2]		46
Short-Term Marketable Securities			24
Long-Term Marketable Securities	[1]		$ 22
[1]	Long-term marketable securities are included in other long-term assets on our unaudited condensed consolidated balance sheets.
[2]	As of September 30, 2018 and December 31, 2017, any unrealized gains or losses related to our marketable securities were not material.
[3]	As of September 30, 2018 and December 31, 2017, our restricted cash, which primarily consists of escrowed security deposits, was not material and is included in other long-term assets on our unaudited condensed consolidated balance sheets.

Financial Instruments - Additio

Financial Instruments - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)Contract	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)Contract
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial instruments including money market funds maturities period		90 days		90 days
Maximum maturities period of long-term marketable securities		3 years		3 years
Minimum maturities period of long-term marketable securities		1 year		1 year
Maximum remaining maturity for short-term marketable securities		12 months		12 months
Minimum maturities of short-term marketable securities		90 days		90 days
Derivative instruments not designated as hedging instruments, description of terms		We use foreign currency forward contracts to reduce the effects of foreign currency exchange rate fluctuations on our cash flows primarily for the Euro versus the U.S. Dollar. We do not use derivatives for trading or speculative purposes. Counterparties to foreign currency exchange derivatives consist of major international financial institutions. We monitor our positions and the credit ratings of the counterparties involved and, by policy limits, the amount of credit exposure to any one party. Our foreign currency forward contracts, which we have entered into to date, have not been designated as hedges and typically have had current maturities of less than 90 days.
Net gain (loss) related to forward contracts		$ 3
Number of outstanding derivatives contracts | Contract		0		0
Cost method investments		$ 12		$ 12
Cost-method Investments | Interest Income and Other, Net
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain (Loss) on investments	$ 2		$ 2

Debt - Two Thousand Fifteen Cre

Debt - Two Thousand Fifteen Credit Facility - Additional Information (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Total interest expense and commitments fees	$ 4,000,000		$ 4,000,000	$ 10,000,000	$ 11,000,000
2015 Credit Facility
Debt Instrument [Line Items]
Total interest expense and commitments fees			$ 2,000,000	2,000,000	$ 4,000,000
2015 Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility	1,200,000,000			$ 1,200,000,000
Interest rate description				Borrowings under the 2015 Credit Facility generally bear interest, at the Company’s option, at a rate per annum equal to either (i) the Eurocurrency Borrowing rate, or the adjusted LIBO rate for the interest period in effect for such borrowing; plus an applicable margin ranging from 1.25% to 2.00% (“Eurocurrency Spread”), based on the Company’s leverage ratio; or (ii) the Alternate Base Rate (“ABR”) Borrowing, which is the greatest of (a) the Prime Rate in effect on such day, (b) the New York Fed Bank Rate in effect on such day plus 1/2 of 1.00% per annum and (c) the Adjusted LIBO Rate (or LIBO rate multiplied by the Statutory Reserve Rate) for an interest period of one month plus 1.00%; in addition to an applicable margin ranging from 0.25% to 1.00% (“ABR Spread”), based on the Company’s leverage ratio.
Credit facility, maturity date				May 12, 2022
Credit facility, expiration period				5 years
Line of credit facility additional borrowing	5,000,000			$ 5,000,000
Repayments of debt				235,000,000
Cash repatriation of foreign earnings		$ 325,000,000
Outstanding borrowings	0			$ 0
Line Of Credit Facility Unused Capacity Commitment Fee Percentage				0.15%
2015 Credit Facility | Letter of Credit
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility	15,000,000			$ 15,000,000
Letters of credit outstanding amount	3,000,000			3,000,000
2015 Credit Facility | Borrowings On Same Day Notice
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility	$ 40,000,000			$ 40,000,000
2015 Credit Facility | Minimum | Revolving Credit Facility
Debt Instrument [Line Items]
Line Of Credit Facility Unused Capacity Commitment Fee Percentage				0.15%
2015 Credit Facility | Minimum | Revolving Credit Facility | Eurocurrency Spread
Debt Instrument [Line Items]
Basis spread on variable rate				1.25%
2015 Credit Facility | Minimum | Revolving Credit Facility | Adjusted London Interbank Offered Rate
Debt Instrument [Line Items]
Basis spread on variable rate				0.25%
2015 Credit Facility | Minimum | Revolving Credit Facility | ABR Spread
Debt Instrument [Line Items]
Basis spread on variable rate				0.25%
2015 Credit Facility | Maximum | Revolving Credit Facility
Debt Instrument [Line Items]
Line Of Credit Facility Unused Capacity Commitment Fee Percentage				0.30%
2015 Credit Facility | Maximum | Revolving Credit Facility | Eurocurrency Spread
Debt Instrument [Line Items]
Basis spread on variable rate				2.00%
2015 Credit Facility | Maximum | Revolving Credit Facility | Adjusted London Interbank Offered Rate
Debt Instrument [Line Items]
Basis spread on variable rate				1.00%
2015 Credit Facility | Maximum | Revolving Credit Facility | ABR Spread
Debt Instrument [Line Items]
Basis spread on variable rate				1.00%

Debt - Two Thousand Sixteen Cre

Debt - Two Thousand Sixteen Credit Facility - Additional Information (Details) - 2016 Credit Facility - Revolving Credit Facility - Lender - USD ($)	1 Months Ended	3 Months Ended
	Jun. 30, 2018	Mar. 31, 2017	Dec. 31, 2017	Sep. 07, 2016
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility				$ 73,000,000
Repayments of debt		$ 73,000,000
Outstanding borrowings	$ 0		$ 0
Credit facility, termination date	Jun. 30, 2018

Debt - Chinese Credit Facilitie

Debt - Chinese Credit Facilities - Additional Information (Details) - Chinese Credit Facilities	9 Months Ended
	Sep. 30, 2018USD ($)CreditFacility	Sep. 30, 2018CNY (¥)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Number of credit facilities | CreditFacility	2
Repayments of debt	$ 10,000,000
Chinese Credit Facility Boa
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility	$ 30,000,000
Period of credit facility	1 year
Interest rate description	Borrowings under our Chinese Credit Facility – BOA generally bear interest at a rate based on People’s Bank of China benchmark, including certain adjustments which may be made in accordance with market conditions at the time of borrowing.
Outstanding borrowings	$ 0		$ 0
Chinese Credit Facility JPM
Debt Instrument [Line Items]
Borrowing capacity under Credit Facility	$ 10,000,000	¥ 70,000,000
Period of credit facility	1 year
Interest rate description	Our Chinese Credit Facility—JPM generally bears interest at a rate based on People’s Bank of China benchmark, including certain adjustments which may be made in accordance with market conditions at the time of borrowing.
Outstanding borrowings	$ 0		$ 7,000,000
Line of credit, interest rate basis			5.00%
Line of credit facility additional borrowing	2,000,000
Repayments of debt	$ 10,000,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	Sep. 30, 2018	Jan. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Taxes [Line Items]
Effective tax rate			20.70%	34.20%	30.00%	39.30%
Income tax expense at federal statutory rate					21.00%		35.00%
Income tax expense benefit related to transition tax			$ 2,000,000		$ 2,000,000
Federal tax return overpayment reclassified as other long-term liabilities	$ 25,000,000		$ 25,000,000		25,000,000
Transition tax repayment period			8 years
Remaining unpaid transition tax included in other long-term liabilities	31,000,000		$ 31,000,000		31,000,000
Tax cuts and jobs act, income tax benefit			3,000,000		6,000,000
Accrued interest	14,000,000		14,000,000		14,000,000
Accrued penalties	0		0		0
Tax benefit from subsidiary			$ 1,000,000	$ 2,000,000	$ 2,000,000	$ 5,000,000
Income tax benefit upon Court's 2015 opinion	$ 15,000,000
Minimum | Expedia | IRS | Tax Years 2009 and 2010
Income Taxes [Line Items]
Increase in income tax expense due to proposed adjustments related to transfer pricing with foreign subsidiary, estimated		$ 10,000,000
Maximum | Expedia | IRS | Tax Years 2009 and 2010
Income Taxes [Line Items]
Increase in income tax expense due to proposed adjustments related to transfer pricing with foreign subsidiary, estimated		$ 14,000,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Jan. 31, 2018
Schedule Of Capitalization Equity [Line Items]
Repurchase of common stock, shares	0	2,582,198
Aggregate cost of shares repurchased, common stock		$ 100,000,000
Average price of shares repurchased, common stock		$ 38.73
Remaining authorized share repurchased amount	$ 150,000,000	$ 150,000,000
Maximum
Schedule Of Capitalization Equity [Line Items]
Repurchase of shares of common stock authorized			$ 250,000,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - LTRIP - USD ($) shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Related Party Transaction [Line Items]
Beneficially ownership of shares of common stock			18.2
Percentage taken from outstanding shares of common stock			14.50%
Percentage of beneficially ownership of shares of common stock class B			22.50%
Right to voting			one vote per share
Beneficially ownership of equity securities			57.80%
Related party transactions	$ 0	$ 0	$ 0	$ 0
Class B Common Stock
Related Party Transaction [Line Items]
Beneficially ownership of shares of common stock			12.8
Percentage taken from outstanding shares of common stock			100.00%
Right to voting			Ten votes per share

Segment Information - Additiona

Segment Information - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018Segment
Segment Reporting Information [Line Items]
Number of reportable segment	2
Non-Hotel Segment
Segment Reporting Information [Line Items]
Number of operating segments	3

Segment Information - Summary o

Segment Information - Summary of Segment Information (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenue		$ 458		$ 439		$ 1,269		$ 1,235
Adjusted EBITDA		146	[1]	95	[2]	335	[1]	269	[2]
Depreciation		(20)		(19)		(61)		(57)
Amortization of intangible assets		(8)		(8)		(24)		(25)
Stock-based compensation		(29)		(26)		(90)		(72)
Operating income		89		42		160		115
Other expense, net		(2)		(4)		(10)		(8)
Income before income taxes		87		38		150		107
Provision for income taxes		(18)		(13)		(45)		(42)
Net income		69		25		105		65
Hotel Segment
Segment Reporting Information [Line Items]
Revenue	[3]	305				917
Non-Hotel Segment
Segment Reporting Information [Line Items]
Revenue	[3]	153				352
Operating Segments | Hotel Segment
Segment Reporting Information [Line Items]
Revenue		305		312		917		952
Adjusted EBITDA		99	[1]	51	[2]	276	[1]	223	[2]
Operating Segments | Non-Hotel Segment
Segment Reporting Information [Line Items]
Revenue		153		127		352		283
Adjusted EBITDA		47	[1]	44	[2]	59	[1]	46	[2]
Corporate and Unallocated
Segment Reporting Information [Line Items]
Depreciation		(20)		(19)		(61)		(57)
Amortization of intangible assets		(8)		(8)		(24)		(25)
Stock-based compensation		$ (29)		$ (26)		$ (90)		$ (72)
[1]	Includes allocated general and administrative expenses in our Hotel segment of $17 million and $57 million; and in our Non-Hotel segment of $12 million and $37 million for the three and nine months ended September 30, 2018, respectively.
[2]	Includes allocated general and administrative expenses in our Hotel segment of $22 million and $60 million; and in our Non-Hotel segment of $11 million and $30 million for the three and nine months ended September 30, 2017, respectively.
[3]	Our revenue is recognized primarily at a point in time for both our Hotel and Non-Hotel segments.

Segment Information - Summary_2

Segment Information - Summary of Segment Information (Parenthetical) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
General and administrative	[1]	$ 40	$ 42	$ 129	$ 115
Operating Segments | Hotel Segment
Segment Reporting Information [Line Items]
General and administrative		17	22	57	60
Operating Segments | Non-Hotel Segment
Segment Reporting Information [Line Items]
General and administrative		$ 12	$ 11	$ 37	$ 30
[1]	Includes stock-based compensation expense as follows