CarGurus (CARG) 10-Q 5 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 29, 2020
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Registrant Name	CARGURUS, INC.
Trading Symbol	CARG
Entity Central Index Key	0001494259
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity File Number	001-38233
Entity Tax Identification Number	04-3843478
Entity Address, Address Line One	2 Canal Park
Entity Address, Address Line Two	4th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02141
City Area Code	617
Local Phone Number	354-0068
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Class A Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Class A Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		94,160,683
Class B Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		19,076,500

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 245,941	$ 59,920
Investments		111,692
Accounts receivable, net of allowance for doubtful accounts of $610 and $240, respectively	16,322	22,124
Prepaid expenses and prepaid income taxes	7,325	10,452
Deferred contract costs	9,950	9,544
Other current assets	1,634	4,972
Restricted cash	250	250
Total current assets	281,422	218,954
Property and equipment, net	27,276	27,950
Intangible assets	10,262	3,920
Goodwill	28,357	15,207
Operating lease right-of-use assets	63,525	59,986
Restricted cash	10,627	10,553
Deferred tax assets	27,267	42,713
Deferred contract costs, net of current portion	8,501	10,514
Other non-current assets	3,314	3,826
Total assets	460,551	393,623
Current liabilities
Accounts payable	16,839	36,731
Accrued expenses, accrued income taxes and other current liabilities	17,878	18,262
Deferred revenue	9,678	9,984
Operating lease liabilities	11,472	8,781
Total current liabilities	55,867	73,758
Operating lease liabilities	62,016	60,818
Deferred tax liabilities	304	284
Other non–current liabilities	4,105	1,908
Total liabilities	122,292	136,768
Commitments and contingencies (Note 10)
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued and outstanding
Additional paid-in capital	233,246	205,234
Retained earnings	104,249	51,859
Accumulated other comprehensive income (loss)	651	(350)
Total stockholders’ equity	338,259	256,855
Total liabilities and stockholders’ equity	460,551	393,623
Class A Common Stock
Stockholders’ equity:
Common stock	94	92
Class B Common Stock
Stockholders’ equity:
Common stock	$ 19	$ 20

Unaudited Condensed Consolida_2

Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Allowance for doubtful accounts	$ 610	$ 240
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Class A Common Stock
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	94,016,568	91,819,649
Common stock, shares outstanding	94,016,568	91,819,649
Class B Common Stock
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	19,076,500	20,314,644
Common stock, shares outstanding	19,076,500	20,314,644

Unaudited Condensed Consolida_3

Unaudited Condensed Consolidated Income Statements - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue		$ 147,472	$ 150,462	$ 399,898	$ 430,763
Cost of revenue	[1]	9,762	9,392	31,252	25,740
Gross profit		137,710	141,070	368,646	405,023
Operating expenses:
Sales and marketing		57,618	100,133	189,796	293,238
Product, technology, and development		20,758	17,745	65,729	51,063
General and administrative		14,279	12,322	44,297	36,622
Depreciation and amortization		1,488	1,166	4,529	3,413
Total operating expenses		94,143	131,366	304,351	384,336
Income from operations		43,567	9,704	64,295	20,687
Other income, net:
Interest income		174	759	1,053	2,247
Other income, net		31	251	354	1,258
Total other income, net		205	1,010	1,407	3,505
Income before income taxes		43,772	10,714	65,702	24,192
Provision for (benefit from) income taxes		11,209	330	13,312	(4,783)
Net income		$ 32,563	$ 10,384	$ 52,390	$ 28,975
Net income per share attributable to common stockholders: (Note 12)
Basic		$ 0.29	$ 0.09	$ 0.46	$ 0.26
Diluted		$ 0.29	$ 0.09	$ 0.46	$ 0.26
Weighted-average number of shares of common stock used in computing net income per share attributable to common stockholders:
Basic		113,027,995	111,662,949	112,707,003	111,257,271
Diluted		113,966,863	113,364,775	113,732,616	113,389,695
[1]	I ncludes depreciation and amortization expense for the three months ended September 30, 2020 and 2019 and for the nine months ended September 30, 2020 and 2019 of $944, $952, $4,250, and $2,246, respectively.

Unaudited Condensed Consolida_4

Unaudited Condensed Consolidated Income Statements (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Depreciation and amortization expense	$ 944	$ 952	$ 4,250	$ 2,246

Unaudited Condensed Consolida_5

Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 32,563	$ 10,384	$ 52,390	$ 28,975
Other comprehensive income (loss):
Foreign currency translation adjustment	1,013	(929)	1,001	(997)
Comprehensive income	$ 33,576	$ 9,455	$ 53,391	$ 27,978

Unaudited Condensed Consolida_6

Unaudited Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Class A Common Stock	Class B Common Stock	Common StockClass A Common Stock	Common StockClass B Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2018	$ 194,111			$ 90	$ 21	$ 184,216	$ 9,713	$ 71
Beginning balance, Shares at Dec. 31, 2018				89,728,223	20,702,084
Net income	12,584						12,584
Stock–based compensation expense	7,995					7,995
Issuance of common stock upon exercise of stock options	697					697
Issuance of common stock upon exercise of stock options, Shares				447,210
Issuance of common stock upon vesting of restricted stock units, Shares				297,374
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options	(3,954)					(3,954)
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options, Shares				(102,034)
Foreign currency translation adjustment	(424)							(424)
Ending balance at Mar. 31, 2019	211,009			$ 90	$ 21	188,954	22,297	(353)
Ending balance, Shares at Mar. 31, 2019				90,370,773	20,702,084
Beginning balance at Dec. 31, 2018	194,111			$ 90	$ 21	184,216	9,713	71
Beginning balance, Shares at Dec. 31, 2018				89,728,223	20,702,084
Net income	28,975
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options, Shares		(345,114)
Foreign currency translation adjustment	(997)
Ending balance at Sep. 30, 2019	237,102			$ 91	$ 21	199,228	38,688	(926)
Ending balance, Shares at Sep. 30, 2019				91,312,647	20,502,084
Beginning balance at Mar. 31, 2019	211,009			$ 90	$ 21	188,954	22,297	(353)
Beginning balance, Shares at Mar. 31, 2019				90,370,773	20,702,084
Net income	6,007						6,007
Stock–based compensation expense	9,260					9,260
Issuance of common stock upon exercise of stock options	391					391
Issuance of common stock upon exercise of stock options, Shares				133,838
Issuance of common stock upon vesting of restricted stock units				$ 1		(1)
Issuance of common stock upon vesting of restricted stock units, Shares				362,447
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options	(4,637)					(4,637)
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options, Shares				(122,137)
Foreign currency translation adjustment	356							356
Ending balance at Jun. 30, 2019	222,386			$ 91	$ 21	193,967	28,304	3
Ending balance, Shares at Jun. 30, 2019				90,744,921	20,702,084
Net income	10,384						10,384
Stock–based compensation expense	9,085					9,085
Issuance of common stock upon exercise of stock options	368					368
Issuance of common stock upon exercise of stock options, Shares				144,760
Issuance of common stock upon vesting of restricted stock units, Shares				343,909
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options	(4,192)					(4,192)
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options, Shares		(120,943)		(120,943)
Conversion of common stock, shares issued				200,000
Conversion of common stock, shares converted					(200,000)
Foreign currency translation adjustment	(929)							(929)
Ending balance at Sep. 30, 2019	237,102			$ 91	$ 21	199,228	38,688	(926)
Ending balance, Shares at Sep. 30, 2019				91,312,647	20,502,084
Beginning balance at Dec. 31, 2019	256,855			$ 92	$ 20	205,234	51,859	(350)
Beginning balance, Shares at Dec. 31, 2019		91,819,649	20,314,644	91,819,649	20,314,644
Net income	12,696						12,696
Stock–based compensation expense	11,793					11,793
Issuance of common stock upon exercise of stock options	514					514
Issuance of common stock upon exercise of stock options, Shares				160,668
Issuance of common stock upon vesting of restricted stock units				$ 1		(1)
Issuance of common stock upon vesting of restricted stock units, Shares				308,303
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options	(3,397)					(3,397)
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options, Shares				(106,934)
Conversion of common stock, shares issued				335,741
Conversion of common stock, shares converted					(335,741)
Foreign currency translation adjustment	(493)							(493)
Ending balance at Mar. 31, 2020	277,968			$ 93	$ 20	214,143	64,555	(843)
Ending balance, Shares at Mar. 31, 2020				92,517,427	19,978,903
Beginning balance at Dec. 31, 2019	256,855			$ 92	$ 20	205,234	51,859	(350)
Beginning balance, Shares at Dec. 31, 2019		91,819,649	20,314,644	91,819,649	20,314,644
Net income	52,390
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options, Shares		(337,313)
Foreign currency translation adjustment	1,001
Ending balance at Sep. 30, 2020	338,259			$ 94	$ 19	233,246	104,249	651
Ending balance, Shares at Sep. 30, 2020		94,016,568	19,076,500	94,016,568	19,076,500
Beginning balance at Mar. 31, 2020	277,968			$ 93	$ 20	214,143	64,555	(843)
Beginning balance, Shares at Mar. 31, 2020				92,517,427	19,978,903
Net income	7,131						7,131
Stock–based compensation expense	12,249					12,249
Issuance of common stock upon exercise of stock options	415					415
Issuance of common stock upon exercise of stock options, Shares				84,796
Issuance of common stock upon vesting of restricted stock units, Shares				375,645
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options	(2,389)					(2,389)
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options, Shares				(119,009)
Conversion of common stock, shares issued				3,748
Conversion of common stock, shares converted					(3,748)
Foreign currency translation adjustment	481							481
Ending balance at Jun. 30, 2020	295,855			$ 93	$ 20	224,418	71,686	(362)
Ending balance, Shares at Jun. 30, 2020				92,862,607	19,975,155
Net income	32,563						32,563
Stock–based compensation expense	11,684					11,684
Issuance of common stock upon exercise of stock options	66					66
Issuance of common stock upon exercise of stock options, Shares				31,523
Issuance of common stock upon vesting of restricted stock units, Shares				335,153
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options	(2,922)					(2,922)
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options, Shares		(111,370)		(111,370)
Conversion of common stock				$ 1
Conversion of common stock, shares issued				898,655
Conversion of common stock, shares converted					(898,655)
Conversion of common stock, value					$ (1)
Foreign currency translation adjustment	1,013							1,013
Ending balance at Sep. 30, 2020	$ 338,259			$ 94	$ 19	$ 233,246	$ 104,249	$ 651
Ending balance, Shares at Sep. 30, 2020		94,016,568	19,076,500	94,016,568	19,076,500

Unaudited Condensed Consolida_7

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities
Net income	$ 52,390	$ 28,975
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,779	5,659
Currency gain on foreign denominated transactions	(32)	(927)
Deferred taxes	14,769	(5,025)
Provision for doubtful accounts	1,742	695
Stock-based compensation expense	34,403	25,390
Amortization of deferred contract costs	8,595	5,797
Changes in operating assets and liabilities:
Accounts receivable, net	5,954	(4,984)
Prepaid expenses, prepaid income taxes, and other assets	7,104	(871)
Deferred contract costs	(6,922)	(11,442)
Accounts payable	(19,745)	10,740
Accrued expenses, accrued income taxes, and other current liabilities	(497)	(2,047)
Deferred revenue	(313)	(1,027)
Lease obligations	356	(1,882)
Other non-current liabilities	2,223	500
Net cash provided by operating activities	108,806	49,551
Investing Activities
Purchases of property and equipment	(2,732)	(10,765)
Capitalization of website development costs	(3,045)	(2,074)
Cash paid for acquisition, net of cash acquired	(21,056)	(19,139)
Investments in certificates of deposit		(134,808)
Maturities of certificates of deposit	111,692	122,800
Net cash provided by (used in) investing activities	84,859	(43,986)
Financing Activities
Proceeds from exercise of stock options	995	1,456
Payment of finance lease obligations	(28)	(21)
Payment of withholding taxes and option costs on net share settlement of restricted stock units and stock options	(8,708)	(12,783)
Net cash used in financing activities	(7,741)	(11,348)
Impact of foreign currency on cash, cash equivalents, and restricted cash	171	(97)
Net increase (decrease) in cash, cash equivalents, and restricted cash	186,095	(5,880)
Cash, cash equivalents, and restricted cash at beginning of period	70,723	37,558
Cash, cash equivalents, and restricted cash at end of period	256,818	31,678
Supplemental disclosure of cash flow information:
Cash paid for income taxes	875	153
Unpaid purchases of property and equipment	165	244
Capitalized stock-based compensation expense in website development and internal-use software costs	1,323	950
Cash paid for operating lease liabilities	$ 10,329	$ 8,465

Organization and Business Descr

Organization and Business Description	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Organization and Business Description	1. Organization and Business Description CarGurus, Inc. (the “Company”), is a global, online automotive marketplace connecting buyers and sellers of new and used cars. Using proprietary technology, search algorithms, and innovative data analytics, the Company provides information and analysis that create a differentiated automotive search experience for consumers. The Company’s marketplace empowers users worldwide with unbiased third-party validation on pricing and dealer reputation, as well as other useful information that aids them in finding “Great Deals from Top-Rated Dealers.” The Company is headquartered in Cambridge, Massachusetts and was incorporated in the State of Delaware on June 26, 2015. The Company operates principally in the United States. In addition to the United States, i The Company also operated online marketplaces in Germany, Italy, and Spain until it ceased the operations of each of these marketplaces in the second quarter of 2020.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying interim condensed consolidated financial statements (the “Unaudited Condensed Consolidated Financial Statements”) are unaudited. The Unaudited Condensed Consolidated Financial Statements and related disclosures have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). The Unaudited Condensed Consolidated Financial Statements have also been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. The Unaudited Condensed Consolidated Financial Statements reflect all adjustments, consisting of only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2020 and December 31, 2019, results of operations, comprehensive income, changes in shareholders’ equity for the three and nine months ended September 30, 2020 and 2019 and cash flows for the nine months ended September 30, 2020 and 2019. These interim period results are not necessarily indicative of the results to be expected for any other interim period or the full year. The Unaudited Condensed Consolidated Financial Statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 14, 2020 (the “Annual Report”). Principles of Consolidation The accompanying Unaudited Condensed Consolidated Financial Statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Subsequent Event Considerations The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the financial statements to provide additional evidence for certain estimates or to identify matters that require additional disclosure. The Company has evaluated all subsequent events and determined that there are no material recognized or unrecognized subsequent events requiring disclosure . Use of Estimates The preparation of the Unaudited Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting period. Significant estimates relied upon in preparing these Unaudited Condensed Consolidated Financial Statements Although the Company regularly assesses these estimates, actual results could differ materially from these estimates. The Company bases its estimates on historical experience and various other assumptions that it believes to be reasonable under the circumstances. Actual results may differ from management’s estimates if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made. Concentration of Credit Risk The Company has no significant off‑balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents, investments, and trade accounts receivable. The Company maintains its cash, cash equivalents, and investments principally with accredited financial institutions of high credit standing. Although the Company deposits its cash, cash equivalents, and investments with multiple financial institutions, its deposits may often exceed governmental insured limits. Credit risk with respect to accounts receivable is dispersed due to the large number of customers. The Company routinely assesses the creditworthiness of its customers. The Company generally has not experienced any material losses related to receivables from individual customers, or groups of customers. The Company does not require collateral. Due to these factors, no additional credit risk beyond amounts provided for collection losses is believed by management to be probable in the Company’s accounts receivable. For the three and nine months ended September 30, 2020 and 2019, no individual customer accounted for more than 10% of total revenue. As of September 30, 2020 , two customers each accounted for approximately 10% of net accounts receivable. As of December 31, 2019, one customer accounted for approximately 18% of net accounts receivable. Included in net accounts receivable at September 30, 2020 and December 31, 2019, are $6,869 and $8,880, respectively, of unbilled accounts receivable primarily related to advertising customers that are generally billed within a quarter subsequent to services being rendered. Significant Accounting Policies The Unaudited Condensed Consolidated Financial Statements reflect the application of certain significant accounting policies as described below and elsewhere in these notes to the Unaudited Condensed Consolidated Financial Statements As of September 30, 2020, the Company’s significant accounting policies and estimates, which are detailed in the Annual Report, have not changed, other than those impacted by new accounting standards as described below. These changes were not material. Allowance for Credit Losses T he Company is exposed to credit losses primarily through its trade accounts receivable. The Company determines the required allowance for expected credit losses using information such as historical loss trends, current conditions, and reasonable and supportable forecasts of economic conditions such as the impacts of the . Amounts are charged against the allowance when it is determined that expected credit losses may occur. In light of the COVID-19 pandemic, the Company assessed the implications on accounts receivable and increased its allowance for doubtful accounts to $ 610 Below is a summary of the changes in the Company’s allowance for doubtful accounts for the nine months ended September 30, 2020: Balance at Beginning of Period Provision Write – Net of Recoveries Balance at End of Period Nine Months Ended September 30, 2020 $ 240 $ 1,742 $ (1,372 ) $ 610 Recent Accounting Pronouncements Adopted Goodwill and Intangibles In January 2017, the FASB issued ASU Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ASU . Credit Losses In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ASU Recent Accounting Pronouncements Not Yet Adopted From time to time, new accounting pronouncements are issued by the FASB Income Taxes In December 2019, the FASB issued ASU 2019-12, Income Taxes – Simplifying the Accounting for Income Taxes

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2020
Revenue From Contract With Customer [Abstract]
Revenue Recognition	3. Revenue Recognition Revenue Recognition The following table summarizes revenue from contracts with customers by geographical region and by revenue source for the three and nine months ended September 30, 2020 and 2019. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 United States Marketplace subscription revenue $ 121,814 $ 127,807 $ 330,295 $ 365,180 Advertising and other revenue 16,598 13,830 45,869 41,870 Total 138,412 141,637 376,164 407,050 International Marketplace subscription revenue 8,139 7,735 21,477 20,301 Advertising and other revenue 921 1,090 2,257 3,412 Total 9,060 8,825 23,734 23,713 Total Revenue Marketplace subscription revenue 129,953 135,542 351,772 385,481 Advertising and other revenue 17,519 14,920 48,126 45,282 Total $ 147,472 $ 150,462 $ 399,898 $ 430,763 The Company provides disaggregation of revenue based on the United States versus International geographical region classification and based on the marketplace subscription versus advertising and other revenue classification as it believes these categories best depict how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. ASC Topic 606, Revenue from Contracts with Customers (“Topic 606”) requires that the Company disclose the aggregate amount of transaction price that is allocated to performance obligations that have not yet been satisfied as of the relevant quarter end. For contracts with an original expected duration greater than one year, the aggregate amount of the transaction price allocated to performance obligations that were unsatisfied For contracts with an original expected duration of one year or less, the Company has applied the practical expedient available under Topic 606 to not disclose the amount of transaction price allocated to unsatisfied performance obligations as of September 30, 2020. For performance obligations not satisfied as of September 30, 2020, and to which this expedient applies, the nature of the performance obligations, the variable consideration and any consideration from contracts with customers not included in the transaction price are consistent with performance obligations satisfied as of September 30, 2020. Revenue recognized during the three months ended September 30, 2020 and 2019 and nine months ended September 30, 2020 and 2019, from amounts included in deferred revenue at the beginning of the period, was approximately $8,195, $8,479, $9,984 and $8,811, respectively. In response to the COVID-19 pandemic, the Company reduced the subscription fees for paying dealers by at least 50% on all marketplace subscriptions for the April and May 2020 service periods, as well as provided a fee reduction on all June 2020 marketplace subscriptions of 20% for paying dealers in the United States and Canada and 50% for paying dealers in the United Kingdom. These fee reductions resulted in a modification to contracts with initial contractual periods greater than one month. For any contract modified, the Company calculated the remaining transaction price and allocated the consideration over the remaining performance obligations. These fee reductions materially and adversely impacted revenue for the second quarter of 2020 and had an immaterial impact for the third quarter of 2020.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Acquisitions	4. Acquisitions On January 16, 2020, the Company acquired Autolist, an automotive shopping platform based in San Francisco, California, pursuant to an Agreement and Plan of Merger by and among the Company, Alpine Merger Sub, Inc., a Delaware corporation and wholly-owned subsidiary of the Company (“Merger Sub”), Auto List, Inc., a Delaware corporation (“Target”), and the securityholders’ representative therein, pursuant to which, among other things, the Company acquired Target through the merger of Merger Sub with and into Target (the “Merger”), with Target surviving as a wholly owned subsidiary of the Company. The Company paid an aggregate of $ million, net of cash acquired, to consummate the Merger. The amount paid includes $ 2.2 million that is held in escrow to secure post-closing claims. The Merger is intended to both expand the Company’s consumer audience in the United States and enhance its value proposition for subscribing dealers. As of September 30, 2020, the Company incurred total acquisition-related costs of $1.4 million related to the Merger. For the three months ended September 30, 2020, the Company incurred no acquisition-related costs. For the nine months ended September 30, 2020, the Company incurred total acquisition-related costs of $1.0 million. Acquisition-related costs were excluded from the purchase price allocation as they were primarily comprised of one-time severance and bonus related expenses. For the nine months ended September 30, 2020, $0.5 million, $0.3 million, and $0.2 million of acquisition-related costs were recorded as operating expense and allocated to product, technology, and development, general and administrative, and sales and marketing, respectively, within the Unaudited Condensed Consolidated Income Statement. The acquisition has been accounted for as a business combination under the acquisition method and, accordingly, the total purchase price is allocated to the acquired assets and assumed liabilities. The following table presents the adjusted purchase price allocation recorded in the Company’s Unaudited Condensed Consolidated Balance Sheet as of the acquisition date, which is subject to finalization for tax-related items: Adjusted Fair Value at Date of Acquisition (4) Cash and cash equivalents $ 50 Restricted cash 220 Accounts receivable 1,862 Intangible assets (1) 7,600 Goodwill (2) 12,477 Operating lease right-of-use assets 2,169 Other assets, net 162 Accounts payable and accrued expenses (358 ) Operating lease liabilities - current (446 ) Operating lease liabilities - non-current (1,723 ) Deferred tax liabilities (3) (687 ) Total purchase price $ 21,326 (1) Identifiable definite-lived intangible assets were comprised of brand, developed technology, and customer relationships of $5,600, $1,200, and $800, respectively, with estimated useful lives of 9 years, 3 years, and 3 years, respectively, which will be amortized on a straight-line basis over their estimated useful lives. The fair value of the brand has been estimated using the multi-period excess earnings method which is a variation of the income approach. The fair value of the developed technology and customer relationships has been estimated using a cost approach, which assesses the cost to redevelop the app and technology, and relationships, respectively. (2) The goodwill represents the excess value of the purchase price over net assets acquired. The goodwill in this transaction is primarily attributable to expected consumer traffic growth and shopper connections for dealers across both the CarGurus and Autolist websites, creating additional value for the Company’s premium subscription customers. All goodwill is assigned to the United States reporting segment. The acquisition of Autolist is treated as a stock acquisition for tax purposes and goodwill is not deductible for tax purposes. (3) The estimated deferred tax liability corresponds to the acquired intangible assets which have no tax basis. (4) The Company refined its estimates of the fair value of certain accounts included within the preliminary purchase price allocation, which resulted in an immaterial adjustment to accounts receivable, cash paid, deferred tax liability and goodwill. Actual and pro forma results for this acquisition have not been presented as the financial impact to the Company’s Unaudited Condensed Consolidated Financial Statements

Fair Value of Financial Instrum

Fair Value of Financial Instruments Including Cash, Cash Equivalents, and Investments	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments Including Cash, Cash Equivalents, and Investments	5. Fair Value of Financial Instruments Including Cash, Cash Equivalents, and Investments The following tables present, for each of the fair value levels, the Company’s assets that are measured at fair value on a recurring basis at September 30, 2020 and at December 31, 2019: At September 30, 2020 Quoted Prices in Active Markets for Identical Assets (Level 1 Inputs) Significant Other Observable Inputs (Level 2 Inputs) Significant Unobservable Inputs (Level 3 Inputs) Total Cash equivalents: Money market funds $ 172,427 $ — $ — $ 172,427 Total $ 172,427 $ — $ — $ 172,427 At December 31, 2019 Quoted Prices in Active Markets for Identical Assets (Level 1 Inputs) Significant Other Observable Inputs (Level 2 Inputs) Significant Unobservable Inputs (Level 3 Inputs) Total Cash equivalents: Money market funds $ 29,196 $ — $ — $ 29,196 Investments: Certificates of deposit — 111,692 — 111,692 Total $ 29,196 $ 111,692 $ — $ 140,888 Certificates of deposit at December 31, 2019 had maturity dates of one year or less. The Company measures eligible assets and liabilities at fair value with changes in value recognized in earnings. There were no liabilities that were measured at fair value as of September 30, 2020 and December 31, 2019. Fair value treatment may be elected either upon initial recognition of an eligible asset or liability or, for an existing asset or liability, if an event triggers a new basis of accounting. The Company did not elect to remeasure any of its existing financial assets and did not elect the fair value option for any financial assets transacted during the nine months ended September 30, 2020 or the year ended December 31, 2019. Cash and cash equivalents primarily consist of cash on deposit with banks and amounts held in interest-bearing money market accounts. Cash equivalents are carried at cost, which approximates their fair market value. The Company considers all highly liquid investments with an original maturity of 90 days or less at the date of purchase to be cash equivalents. Investments not classified as cash equivalents with maturities one year or less from the balance sheet date are classified as short-term investments, while investments with maturities in excess of one year from the balance sheet date are classified as long-term investments. Management determines the appropriate classification of investments at the time of purchase and re-evaluates such determination at each balance sheet date. The Company held no investments at September 30, 2020. The following is a summary of investments as of December 31, 2019: At December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Investments: Certificates of deposit due in one year or less $ 111,692 $ — $ — $ 111,692 Total $ 111,692 $ — $ — $ 111,692

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Property and Equipment, Net	6. Property and Equipment, Net Property and equipment, net consists of the following: At September 30, 2020 At December 31, 2019 Computer equipment $ 8,057 $ 7,923 Capitalized software 181 181 Capitalized website development 15,451 11,083 Furniture and fixtures 7,314 6,809 Leasehold improvements 20,492 19,507 Construction in progress 1,072 524 Finance lease right-of-use assets 50 78 52,617 46,105 Less accumulated depreciation and amortization (25,341 ) (18,155 ) Property and equipment, net $ 27,276 $ 27,950 Depreciation and amortization expense, excluding amortization of intangible assets, was $1,937, $1,951, $7,367, and $5,173

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	7. Goodwill and Other Intangible Assets Goodwill The changes in the carrying value of goodwill were as follows: Balance at December 31, 2019 $ 15,207 Autolist acquisition (1) 12,477 Foreign currency translation adjustment 673 Balance at September 30, 2020 $ 28,357 (1) See Note 4 of the Unaudited Condensed Consolidated Financial Statements included elsewhere in this Quarterly Report. The Company tests goodwill for impairment at least annually or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. As a result of the COVID-19 pandemic, the Company assessed its goodwill for impairment concluding that there was no impairment as of September 30, 2020. Other Intangible Assets Intangible assets as of September 30, 2020 and December 31, 2019 consist of the following: At September 30, 2020 Weighted Average Remaining Useful Life (years) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Brand 8.7 $ 9,257 $ 995 $ 8,262 Customer relationships 1.8 1,866 782 1,084 Developed technology 2.3 1,200 284 916 Total $ 12,323 $ 2,061 $ 10,262 At December 31, 2019 Weighted Average Remaining Useful Life (years) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Brand 10.0 $ 3,524 $ 313 $ 3,211 Customer relationships 2.0 1,045 336 709 Total $ 4,569 $ 649 $ 3,920 The Company recorded amortization expense related to intangible assets of $495, $167, $1,412, and $486 for the three months ended September 30, 2020 and 2019 and the nine months ended September 30, 2020, and 2019, respectively The estimated useful life of the PistonHeads brand and customer relationships is 11 years and 3 years, respectively. The estimated useful life of the Autolist brand, customer relationships and developed technology is 9 years, 3 years, and 3 years, respectively. The Company evaluates the useful lives of these assets on an annual basis and tests for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets. As a result of the COVID-19 pandemic, the Company assessed its long-lived assets for impairment and concluded that there was no impairment as of September 30, 2020. Estimated amortization expense of intangible assets for future periods as of September 30, 2020 is as follows: Year Ending December 31, Amortization Expense Remainder of 2020 $ 484 2021 1,938 2022 1,704 2023 971 2024 953 2025 953 Thereafter 3,259 Total $ 10,262

Accrued Expenses, Accrued Incom

Accrued Expenses, Accrued Income Taxes and Other Current Liabilities	9 Months Ended
	Sep. 30, 2020
Accrued Liabilities Current [Abstract]
Accrued Expenses, Accrued Income Taxes and Other Current Liabilities	8. Accrued Expenses, Accrued Income Taxes and Other Current Liabilities Accrued expenses, accrued income taxes and other current liabilities consist of the following: At September 30, 2020 At December 31, 2019 Accrued bonus $ 8,841 $ 8,637 Accrued commissions 2,824 3,153 Other accrued expenses, accrued income taxes and other current liabilities 6,213 6,472 Total $ 17,878 $ 18,262

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2020
Restructuring And Related Activities [Abstract]
Restructuring	9. Restructuring On April 13, 2020, the Board of Directors of the Company approved an expense reduction plan to address the impact of the COVID-19 pandemic on the Company’s business (the “Expense Reduction Plan”), pursuant to which the Company initiated a reduction in its workforce of approximately 13%, ceased operation of its Germany, Italy and Spain marketplaces, and halted expansion efforts in any new international markets. The Expense Reduction Plan was completed in the second quarter of 2020 and during such quarter resulted in restructuring charges of $3,248 for employee severance and related benefits expense and $1,019 The following table summarizes restructuring accrual activity for employee severance and related benefits expense for the nine months ended September 30, 2020: Employee Severance and Related Benefits Balance at December 31, 2019 $ — Charges 3,248 Cash disbursements (2,581 ) Noncash settlements (667 ) Balance at September 30, 2020 $ — For the three months ended September 30, 2020, no employee severance and related benefits expense was recorded. For the nine months ended September 30, 2020, $2,160, $737, $207, and $144 of employee severance and related benefits expense was recorded as sales and marketing, product, technology, and development, cost of revenue, and general and administrative All of the accrued e were paid as of September 30, 2020 and were recorded within on the Unaudited Condensed Consolidated Balance Sheets, prior to payout. For the nine months ended September 30, 2020, $667 of employee For the three months ended September 30, 2020, no write-off of capitalized website development costs or deferred was recorded. were recorded as cost of revenue and sales and marketing, respectively, within the Unaudited Condensed Consolidated Income Statement. was recorded as depreciation and amortization within the .

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies Contractual Obligations and Commitments All of the Company’s property, equipment, and internal-use software have been purchased with cash with the exception of amounts related to unpaid property and equipment as disclosed in the Unaudited Condensed Consolidated Statements of Cash Flows and immaterial amounts Leases The Company’s primary operating lease obligations consist of various leases for office space in: Boston, Massachusetts; Cambridge, Massachusetts; San Francisco, California; and Dublin, Ireland. The Company also has an operating lease obligation for data center space in Needham, Massachusetts. As of September 30, 2020, there were no material changes in the Company’s material leases from those disclosed in the Annual Report, other than as discussed below. On June 12, 2020, the Company amended its operating lease agreement in Boston, Massachusetts at 1001 Boylston Street, which was originally entered into on December 19, 2019. Pursuant to this amendment, the Company exercised its right to reduce the amount of office space agreed to under the lease to 225,428 square feet, and the parties agreed to certain other changes to the lease as set forth in the amendment. As the lease has been signed but the lease term has not commenced, there is no impact to the Unaudited Condensed Consolidated Financial Statements. On January 10, 2019, Auto List, Inc., which the Company acquired on January 16, 2020, entered into an operating lease in San Francisco, California at 332 Pine St. for the lease of 6,345 square feet of office space with a non-cancellable lease term through 2024. The lease provides for annual rent increases through the term of the lease. The Company’s leases in Boston, Massachusetts, Cambridge, Massachusetts and San Francisco, California have associated letters of credit, which are recorded as restricted cash within the Unaudited Condensed Consolidated Balance Sheet. At September 30, 2020 and December 31, 2019, restricted cash was $10,877 and $10,803, respectively, and primarily related to cash held at a financial institution in an interest‑bearing cash account as collateral for the letters of credit related to the contractual provisions for the Company’s building leases. At September 30, 2020 and December 31, 2019, portions of restricted cash were classified as a short-term asset and long‑term asset, as disclosed on the Unaudited Condensed Consolidated Balance Sheet. Legal Matters From time to time the Company may become involved in legal proceedings or be subject to claims arising in the ordinary course of its business. The Company is not presently subject to any pending or threatened litigation that it believes, if determined adversely to the Company, individually, or taken together, would reasonably be expected to have a material adverse effect on its business or financial results. Guarantees and Indemnification Obligations In the ordinary course of business, the Company enters into agreements with its customers, partners and service providers that include commercial provisions with respect to licensing, infringement, indemnification, and other common provisions. The Company does not, in the ordinary course, agree to guaranty or indemnification obligations for the Company under its contracts with customers. Based on historical experience and information known at September 30, 2020 and December 31, 2019,

Stock-based Compensation

Stock-based Compensation	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based Compensation	11. Stock-based Compensation The following two tables show stock compensation expense by award type and where the stock compensation expense is recorded in the Company’s Unaudited Condensed Consolidated Income Statements Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Options $ — $ 35 $ 17 $ 130 Restricted stock units 11,030 8,726 34,617 25,260 Total stock-based compensation expense $ 11,030 $ 8,761 $ 34,634 $ 25,390 Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Cost of revenue $ 57 $ 92 $ 241 $ 268 Sales and marketing expense 2,450 2,520 8,206 7,392 Product, technology, and development expense 5,140 3,938 15,861 11,118 General and administrative expense 3,383 2,211 10,326 6,612 Total stock-based compensation expense $ 11,030 $ 8,761 $ 34,634 $ 25,390 Excluded from stock-based compensation expense is $656, $324, $1,323, and $950 of capitalized website development and internal-use software costs for the three months ended September 30, 2020 and 2019 and the nine months ended September 30, 2020, and 2019, respectively. During the three months ended September 30, 2020 and 2019 and the nine months ended September 30, 2020 and 2019 , the Company withheld 111,370 , 120,943 , 337,313 , and 345,114 shares of Class A common stock, respectively, to satisfy employee tax withholding requirements and option exercise costs due to net share settlements and cashless exercises of options . The shares withheld return to the authorized, but unissued pool under the Company’s Omnibus Equity Compensation Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements and for option exercise costs were $2,922 , $4,192 , $8,708 , and $12,783 for the three months ended September 30, 2020 and 2019 and the nine months ended September 30, 2020 , and 2019 , respectively , and are reflected as a financing activity within the Unaudited Condensed Consolidated Statements of Cash Flows .

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Earnings Per Share	12. Earnings Per Share Net income per share for the three and nine months ended September 30, 2020 and 2019 is computed by dividing net income by the weighted-average number of common shares outstanding during the reporting period. The Company computes the weighted-average number of common shares outstanding during the reporting period using the total number of shares of Class A 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 during the reporting period. The Company has two classes of common stock authorized: Class A common stock and Class B common stock. The rights of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. Each share of Class A common stock is entitled to one vote per share and each share of Class B common stock is entitled to ten votes per share. Each share of Class B common stock is convertible into one share of Class A common stock at the option of the holder at any time or automatically upon certain events described in the Company’s amended and restated certificate of incorporation, including on either the death or voluntary termination of the Company’s Chief Executive Officer. The Company allocates undistributed earnings attributable to common stock between the common stock classes on a one‑to‑one During the three months ended September 30, 2020 and 2019, holders of Class B common stock converted 898,655 and 200,000 shares of Class B common stock to Class A common stock, respectively. During the nine months ended September 30, 2020 and 2019, holders of Class B common stock converted 1,238,144 200,000 shares of Class B common stock to Class A common stock, respectively. Diluted net income per share gives effect to all potentially dilutive securities. Potential dilutive securities for the three and nine months ended September 30, 2020 and 2019 consist of shares of common stock issuable upon the exercise of stock options and shares of common stock issuable upon the vesting of restricted stock units (“RSUs”). The dilutive effect of these common stock equivalents is reflected in diluted earnings per share by application of the treasury stock method. For the three and nine months ended September 30, 2020 and 2019, diluted net income per share was calculated by dividing net income by the weighted-average number of shares of common stock outstanding during the period plus the dilutive impact of stock options and shares of common stock issuable upon the vesting of RSUs. The following table presents a reconciliation of the numerator and denominator used in the calculation of basic and diluted net income per share: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net income $ 32,563 $ 10,384 $ 52,390 $ 28,975 Denominator: Weighted-average number of shares of common stock used in computing net income per share attributable to common stockholders — basic 113,027,995 111,662,949 112,707,003 111,257,271 Dilutive effect of share equivalents resulting from stock options 632,581 1,052,758 701,176 1,232,754 Dilutive effect of share equivalents resulting from unvested restricted stock units 306,287 649,068 324,437 899,670 Weighted-average number of shares of common stock used in computing net income per share — diluted 113,966,863 113,364,775 113,732,616 113,389,695 Net income per share attributable to common stockholders: Basic $ 0.29 $ 0.09 $ 0.46 $ 0.26 Diluted $ 0.29 $ 0.09 $ 0.46 $ 0.26 The following potentially dilutive common stock equivalents have been excluded from the calculation of diluted weighted-average shares outstanding for the three and nine months ended September 30, 2020 and 2019, as their effect would have been anti-dilutive for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Restricted stock units outstanding 2,577,713 1,421,473 2,893,491 1,191,286

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes During the three months ended September 30, 2020, the Company recorded an income tax provision of $11,209, representing an effective tax rate of 25.6%. The effective tax rate for the three months ended September 30, 2020 was higher than the statutory tax rate of 21% principally due to state and local income taxes, partially offset by federal and state research and development tax credits. During the three months ended September 30, 2019, the Company recorded income tax provision of $330, representing an effective tax rate of 3.1%. The effective tax rate for the three months ended September 30, 2019 was lower than the statutory tax rate of 21% principally due to excess stock deductions from the taxable compensation of share-based awards and federal and state research and development tax credits, partially offset by state and local income taxes. During the nine months ended September 30, 2020, the Company recorded an income tax provision of $13,312 representing an effective tax rate of During the nine months ended September 30, 2019, the Company recorded an income tax benefit of $4,783, representing an effective tax rate of The Company and its subsidiaries are subject to various United States federal, state, and foreign income taxes. The Company is currently open to examination by the Internal Revenue Service (the “IRS”) and state jurisdictions for the tax years of 2017 and after. The Company is currently open to examination in its foreign jurisdictions for tax years 2017 and after. In 2019, the IRS commenced a federal employment tax audit with respect to the 2016, 2017 and 2018 calendar years, which is still open. In July 2020, the IRS commenced a corporate income tax audit with respect to the 2017 calendar year, which is still open. In August 2020, New York State commenced a sales and use tax audit with respect to 2014 – 2020 sales and use taxes, which is still open. On March 27, 2020, the United States enacted the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). Among other things, the CARES Act includes a net operating loss (“NOL”) carryback provision allowing for NOLs from the 2018, 2019 and 2020 tax years to be used to offset taxable income for the tax years from 2013 to 2017. The Company filed a carryback claim, from which it received a refund of $3,863 during the three months ended September 30, 2020, and will reduce its current gross NOL balance by approximately $18,723 and increase its deferred federal research and development credit by approximately $2,645. The Company does not expect this election to negatively impact its analysis on the valuation allowance for its NOLs or deferred federal research and development credit. The CARES Act also updates the Tax Cuts and Jobs Act of 2017, allowing for the depreciation of leasehold improvements over 15 years, rather than 39 years, and eligibility for bonus depreciation, rather than non-eligibility for bonus depreciation. The Company has made an estimate for the impact as it relates to the 2019 tax year and will file its 2019 return in accordance with the updated guidance in the CARES Act. The CARES Act includes other provisions that may be utilized if the Company meets the eligibility requirements. Although the Company continues to review and evaluate the potential impact and benefit of the CARES Act on its entire business, the Company has primarily focused its review on two provisions that affect both income taxes and non-income taxes. First, the CARES Act temporarily removes the 80% limitation on NOLs to offset taxable income for tax years prior to 2021. Second, the CARES Act allows for the deferral of the employer portion of the Social Security Tax for up to two years, with half due by December 31, 2021 and the remainder due by December 31, 2022. On July 20, 2020, the IRS issued final regulations that provide for a high-tax exception to the Global Intangible Low-Taxed Income (“GILTI”) tax. Specifically, if foreign earnings are subject to a foreign tax rate of at least 90% of the U.S. tax rate, an election can be made to not treat the high-taxed earnings as GILTI income. The final regulations provide the ability for taxpayers to retroactively apply the GILTI high-tax exclusion on an amended return for tax years 2018 and 2019. As a result of the final regulations, the Company is able to exclude certain foreign earnings from its forecasted 2020 GILTI income. With respect to prior tax years, the Company did not have GILTI income in 2018 or 2019 and, therefore, does not have the ability to recognize a benefit by applying the high tax exclusion retroactively.

Segment and Geographic Informat

Segment and Geographic Information	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segment and Geographic Information	14. Segment and Geographic Information The Company has two reportable segments, United States and International. Segment information is presented in the same manner as the Company’s chief operating decision maker (the “CODM”) reviews the Company’s operating results in assessing performance and allocating resources. The CODM reviews revenue and operating income (loss) for each reportable segment as a proxy for the operating performance of the Company’s United States and International operations. The Company’s Chief Executive Officer is the CODM on behalf of both reportable segments. The United States segment derives revenues from marketplace subscriptions, advertising services, and other revenues from customers within the United States. The International segment derives revenues from marketplace subscriptions, advertising services, and other revenues from customers outside of the United States. A majority of the Company’s operational overhead expenses, including technology and personnel costs, and other general and administrative costs associated with running the Company’s business, are incurred in the United States and not allocated to the International segment. Revenue and costs discretely incurred by reportable segments, including depreciation and amortization, are included in the calculation of reportable segment income (loss) from operations. Segment operating income (loss) does not reflect the transfer pricing adjustments related to the Company’s foreign subsidiaries, which are recorded for statutory reporting purposes. Asset information is assessed and reviewed on a global basis. Information regarding the Company’s operations by segment and geographical area is presented as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Segment revenue: United States $ 138,412 $ 141,637 $ 376,164 $ 407,050 International 9,060 8,825 23,734 23,713 Total revenue $ 147,472 $ 150,462 $ 399,898 $ 430,763 Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Segment income (loss) from operations: United States $ 46,462 $ 19,956 $ 82,061 $ 51,456 International (2,895 ) (10,252 ) (17,766 ) (30,769 ) Total income from operations $ 43,567 $ 9,704 $ 64,295 $ 20,687 For the three months ended September 30, 2020, no employee severance and related benefits expense was recorded. For the nine months ended September 30, 2020, employee severance and related benefits expense attributable to the United States and International segments were $2,492 and $756, respectively. For the three months ended September 30, 2020, no write-off of capitalized website development costs or deferred contract costs from international marketplaces was recorded. For the nine months ended September 30, 2020, the entirety of the write-off of capitalized website development costs and deferred contract costs from international marketplaces was attributable to the International segment. The Company ceased the operations of the International segment online marketplaces in Germany, Italy, and Spain in the second quarter of 2020. As of September 30, 2020 As of December 31, 2019 , total assets held outside of the United States were $32,528, primarily attributable to $15,207 of goodwill and $3,920 of intangible assets.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying interim condensed consolidated financial statements (the “Unaudited Condensed Consolidated Financial Statements”) are unaudited. The Unaudited Condensed Consolidated Financial Statements and related disclosures have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). The Unaudited Condensed Consolidated Financial Statements have also been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. The Unaudited Condensed Consolidated Financial Statements reflect all adjustments, consisting of only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2020 and December 31, 2019, results of operations, comprehensive income, changes in shareholders’ equity for the three and nine months ended September 30, 2020 and 2019 and cash flows for the nine months ended September 30, 2020 and 2019. These interim period results are not necessarily indicative of the results to be expected for any other interim period or the full year. The Unaudited Condensed Consolidated Financial Statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 14, 2020 (the “Annual Report”).
Principles of Consolidation	Principles of Consolidation The accompanying Unaudited Condensed Consolidated Financial Statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Subsequent Event Considerations	Subsequent Event Considerations The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the financial statements to provide additional evidence for certain estimates or to identify matters that require additional disclosure. The Company has evaluated all subsequent events and determined that there are no material recognized or unrecognized subsequent events requiring disclosure .
Use of Estimates	Use of Estimates The preparation of the Unaudited Condensed Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting period. Significant estimates relied upon in preparing these Unaudited Condensed Consolidated Financial Statements Although the Company regularly assesses these estimates, actual results could differ materially from these estimates. The Company bases its estimates on historical experience and various other assumptions that it believes to be reasonable under the circumstances. Actual results may differ from management’s estimates if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made.
Concentration of Credit Risk	Concentration of Credit Risk The Company has no significant off‑balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents, investments, and trade accounts receivable. The Company maintains its cash, cash equivalents, and investments principally with accredited financial institutions of high credit standing. Although the Company deposits its cash, cash equivalents, and investments with multiple financial institutions, its deposits may often exceed governmental insured limits. Credit risk with respect to accounts receivable is dispersed due to the large number of customers. The Company routinely assesses the creditworthiness of its customers. The Company generally has not experienced any material losses related to receivables from individual customers, or groups of customers. The Company does not require collateral. Due to these factors, no additional credit risk beyond amounts provided for collection losses is believed by management to be probable in the Company’s accounts receivable. For the three and nine months ended September 30, 2020 and 2019, no individual customer accounted for more than 10% of total revenue. As of September 30, 2020 , two customers each accounted for approximately 10% of net accounts receivable. As of December 31, 2019, one customer accounted for approximately 18% of net accounts receivable. Included in net accounts receivable at September 30, 2020 and December 31, 2019, are $6,869 and $8,880, respectively, of unbilled accounts receivable primarily related to advertising customers that are generally billed within a quarter subsequent to services being rendered.
Significant Accounting Policies	Significant Accounting Policies The Unaudited Condensed Consolidated Financial Statements reflect the application of certain significant accounting policies as described below and elsewhere in these notes to the Unaudited Condensed Consolidated Financial Statements As of September 30, 2020, the Company’s significant accounting policies and estimates, which are detailed in the Annual Report, have not changed, other than those impacted by new accounting standards as described below. These changes were not material.
Allowance for Credit Losses	Allowance for Credit Losses T he Company is exposed to credit losses primarily through its trade accounts receivable. The Company determines the required allowance for expected credit losses using information such as historical loss trends, current conditions, and reasonable and supportable forecasts of economic conditions such as the impacts of the . Amounts are charged against the allowance when it is determined that expected credit losses may occur. In light of the COVID-19 pandemic, the Company assessed the implications on accounts receivable and increased its allowance for doubtful accounts to $ 610 Below is a summary of the changes in the Company’s allowance for doubtful accounts for the nine months ended September 30, 2020: Balance at Beginning of Period Provision Write – Net of Recoveries Balance at End of Period Nine Months Ended September 30, 2020 $ 240 $ 1,742 $ (1,372 ) $ 610
Recent Accounting Pronouncements Adopted	Recent Accounting Pronouncements Adopted Goodwill and Intangibles In January 2017, the FASB issued ASU Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ASU . Credit Losses In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ASU
Goodwill and Intangibles	Goodwill and Intangibles In January 2017, the FASB issued ASU Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ASU . The Company tests goodwill for impairment at least annually or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. As a result of the COVID-19 pandemic, the Company assessed its goodwill for impairment concluding that there was no impairment as of September 30, 2020.
Credit Losses	Credit Losses In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ASU
Recent Accounting Pronouncements not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted From time to time, new accounting pronouncements are issued by the FASB Income Taxes In December 2019, the FASB issued ASU 2019-12, Income Taxes – Simplifying the Accounting for Income Taxes
Income Taxes	Income Taxes In December 2019, the FASB issued ASU 2019-12, Income Taxes – Simplifying the Accounting for Income Taxes
Revenue Recognition	Revenue Recognition The following table summarizes revenue from contracts with customers by geographical region and by revenue source for the three and nine months ended September 30, 2020 and 2019. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 United States Marketplace subscription revenue $ 121,814 $ 127,807 $ 330,295 $ 365,180 Advertising and other revenue 16,598 13,830 45,869 41,870 Total 138,412 141,637 376,164 407,050 International Marketplace subscription revenue 8,139 7,735 21,477 20,301 Advertising and other revenue 921 1,090 2,257 3,412 Total 9,060 8,825 23,734 23,713 Total Revenue Marketplace subscription revenue 129,953 135,542 351,772 385,481 Advertising and other revenue 17,519 14,920 48,126 45,282 Total $ 147,472 $ 150,462 $ 399,898 $ 430,763 The Company provides disaggregation of revenue based on the United States versus International geographical region classification and based on the marketplace subscription versus advertising and other revenue classification as it believes these categories best depict how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. ASC Topic 606, Revenue from Contracts with Customers (“Topic 606”) requires that the Company disclose the aggregate amount of transaction price that is allocated to performance obligations that have not yet been satisfied as of the relevant quarter end. For contracts with an original expected duration greater than one year, the aggregate amount of the transaction price allocated to performance obligations that were unsatisfied For contracts with an original expected duration of one year or less, the Company has applied the practical expedient available under Topic 606 to not disclose the amount of transaction price allocated to unsatisfied performance obligations as of September 30, 2020. For performance obligations not satisfied as of September 30, 2020, and to which this expedient applies, the nature of the performance obligations, the variable consideration and any consideration from contracts with customers not included in the transaction price are consistent with performance obligations satisfied as of September 30, 2020. Revenue recognized during the three months ended September 30, 2020 and 2019 and nine months ended September 30, 2020 and 2019, from amounts included in deferred revenue at the beginning of the period, was approximately $8,195, $8,479, $9,984 and $8,811, respectively. In response to the COVID-19 pandemic, the Company reduced the subscription fees for paying dealers by at least 50% on all marketplace subscriptions for the April and May 2020 service periods, as well as provided a fee reduction on all June 2020 marketplace subscriptions of 20% for paying dealers in the United States and Canada and 50% for paying dealers in the United Kingdom. These fee reductions resulted in a modification to contracts with initial contractual periods greater than one month. For any contract modified, the Company calculated the remaining transaction price and allocated the consideration over the remaining performance obligations. These fee reductions materially and adversely impacted revenue for the second quarter of 2020 and had an immaterial impact for the third quarter of 2020.
Fair Value of Financial Instruments Including Cash, Cash Equivalents, and Investments	The Company measures eligible assets and liabilities at fair value with changes in value recognized in earnings. There were no liabilities that were measured at fair value as of September 30, 2020 and December 31, 2019. Fair value treatment may be elected either upon initial recognition of an eligible asset or liability or, for an existing asset or liability, if an event triggers a new basis of accounting. The Company did not elect to remeasure any of its existing financial assets and did not elect the fair value option for any financial assets transacted during the nine months ended September 30, 2020 or the year ended December 31, 2019. Cash and cash equivalents primarily consist of cash on deposit with banks and amounts held in interest-bearing money market accounts. Cash equivalents are carried at cost, which approximates their fair market value. The Company considers all highly liquid investments with an original maturity of 90 days or less at the date of purchase to be cash equivalents. Investments not classified as cash equivalents with maturities one year or less from the balance sheet date are classified as short-term investments, while investments with maturities in excess of one year from the balance sheet date are classified as long-term investments. Management determines the appropriate classification of investments at the time of purchase and re-evaluates such determination at each balance sheet date.
Earnings Per Share	Net income per share for the three and nine months ended September 30, 2020 and 2019 is computed by dividing net income by the weighted-average number of common shares outstanding during the reporting period. The Company computes the weighted-average number of common shares outstanding during the reporting period using the total number of shares of Class A 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 during the reporting period. The Company has two classes of common stock authorized: Class A common stock and Class B common stock. The rights of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. Each share of Class A common stock is entitled to one vote per share and each share of Class B common stock is entitled to ten votes per share. Each share of Class B common stock is convertible into one share of Class A common stock at the option of the holder at any time or automatically upon certain events described in the Company’s amended and restated certificate of incorporation, including on either the death or voluntary termination of the Company’s Chief Executive Officer. The Company allocates undistributed earnings attributable to common stock between the common stock classes on a one‑to‑one

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Changes in Allowance for Doubtful Accounts	Below is a summary of the changes in the Company’s allowance for doubtful accounts for the nine months ended September 30, 2020: Balance at Beginning of Period Provision Write – Net of Recoveries Balance at End of Period Nine Months Ended September 30, 2020 $ 240 $ 1,742 $ (1,372 ) $ 610

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue From Contract With Customer [Abstract]
Summary of Revenue from Contracts with Customers by Geographical Region and by Revenue	The following table summarizes revenue from contracts with customers by geographical region and by revenue source for the three and nine months ended September 30, 2020 and 2019. Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 United States Marketplace subscription revenue $ 121,814 $ 127,807 $ 330,295 $ 365,180 Advertising and other revenue 16,598 13,830 45,869 41,870 Total 138,412 141,637 376,164 407,050 International Marketplace subscription revenue 8,139 7,735 21,477 20,301 Advertising and other revenue 921 1,090 2,257 3,412 Total 9,060 8,825 23,734 23,713 Total Revenue Marketplace subscription revenue 129,953 135,542 351,772 385,481 Advertising and other revenue 17,519 14,920 48,126 45,282 Total $ 147,472 $ 150,462 $ 399,898 $ 430,763

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Summary of Preliminary Purchase Price Allocation	The following table presents the adjusted purchase price allocation recorded in the Company’s Unaudited Condensed Consolidated Balance Sheet as of the acquisition date, which is subject to finalization for tax-related items: Adjusted Fair Value at Date of Acquisition (4) Cash and cash equivalents $ 50 Restricted cash 220 Accounts receivable 1,862 Intangible assets (1) 7,600 Goodwill (2) 12,477 Operating lease right-of-use assets 2,169 Other assets, net 162 Accounts payable and accrued expenses (358 ) Operating lease liabilities - current (446 ) Operating lease liabilities - non-current (1,723 ) Deferred tax liabilities (3) (687 ) Total purchase price $ 21,326 (1) Identifiable definite-lived intangible assets were comprised of brand, developed technology, and customer relationships of $5,600, $1,200, and $800, respectively, with estimated useful lives of 9 years, 3 years, and 3 years, respectively, which will be amortized on a straight-line basis over their estimated useful lives. The fair value of the brand has been estimated using the multi-period excess earnings method which is a variation of the income approach. The fair value of the developed technology and customer relationships has been estimated using a cost approach, which assesses the cost to redevelop the app and technology, and relationships, respectively. (2) The goodwill represents the excess value of the purchase price over net assets acquired. The goodwill in this transaction is primarily attributable to expected consumer traffic growth and shopper connections for dealers across both the CarGurus and Autolist websites, creating additional value for the Company’s premium subscription customers. All goodwill is assigned to the United States reporting segment. The acquisition of Autolist is treated as a stock acquisition for tax purposes and goodwill is not deductible for tax purposes. (3) The estimated deferred tax liability corresponds to the acquired intangible assets which have no tax basis. (4) The Company refined its estimates of the fair value of certain accounts included within the preliminary purchase price allocation, which resulted in an immaterial adjustment to accounts receivable, cash paid, deferred tax liability and goodwill.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments Including Cash, Cash Equivalents, and Investments (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value Levels, Assets Measured at Fair Value on Recurring Basis	The following tables present, for each of the fair value levels, the Company’s assets that are measured at fair value on a recurring basis at September 30, 2020 and at December 31, 2019: At September 30, 2020 Quoted Prices in Active Markets for Identical Assets (Level 1 Inputs) Significant Other Observable Inputs (Level 2 Inputs) Significant Unobservable Inputs (Level 3 Inputs) Total Cash equivalents: Money market funds $ 172,427 $ — $ — $ 172,427 Total $ 172,427 $ — $ — $ 172,427 At December 31, 2019 Quoted Prices in Active Markets for Identical Assets (Level 1 Inputs) Significant Other Observable Inputs (Level 2 Inputs) Significant Unobservable Inputs (Level 3 Inputs) Total Cash equivalents: Money market funds $ 29,196 $ — $ — $ 29,196 Investments: Certificates of deposit — 111,692 — 111,692 Total $ 29,196 $ 111,692 $ — $ 140,888
Schedule of Investments	The Company held no investments at September 30, 2020. The following is a summary of investments as of December 31, 2019: At December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Investments: Certificates of deposit due in one year or less $ 111,692 $ — $ — $ 111,692 Total $ 111,692 $ — $ — $ 111,692

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2020
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consists of the following: At September 30, 2020 At December 31, 2019 Computer equipment $ 8,057 $ 7,923 Capitalized software 181 181 Capitalized website development 15,451 11,083 Furniture and fixtures 7,314 6,809 Leasehold improvements 20,492 19,507 Construction in progress 1,072 524 Finance lease right-of-use assets 50 78 52,617 46,105 Less accumulated depreciation and amortization (25,341 ) (18,155 ) Property and equipment, net $ 27,276 $ 27,950

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Changes in Carrying Value of Goodwill	The changes in the carrying value of goodwill were as follows: Balance at December 31, 2019 $ 15,207 Autolist acquisition (1) 12,477 Foreign currency translation adjustment 673 Balance at September 30, 2020 $ 28,357 (1) See Note 4 of the Unaudited Condensed Consolidated Financial Statements included elsewhere in this Quarterly Report.
Summary of Other Intangible Assets	Intangible assets as of September 30, 2020 and December 31, 2019 consist of the following: At September 30, 2020 Weighted Average Remaining Useful Life (years) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Brand 8.7 $ 9,257 $ 995 $ 8,262 Customer relationships 1.8 1,866 782 1,084 Developed technology 2.3 1,200 284 916 Total $ 12,323 $ 2,061 $ 10,262 At December 31, 2019 Weighted Average Remaining Useful Life (years) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Brand 10.0 $ 3,524 $ 313 $ 3,211 Customer relationships 2.0 1,045 336 709 Total $ 4,569 $ 649 $ 3,920
Summary of Estimated Amortization Expense of Intangible Assets	Estimated amortization expense of intangible assets for future periods as of September 30, 2020 is as follows: Year Ending December 31, Amortization Expense Remainder of 2020 $ 484 2021 1,938 2022 1,704 2023 971 2024 953 2025 953 Thereafter 3,259 Total $ 10,262

Accrued Expenses, Accrued Inc_2

Accrued Expenses, Accrued Income Taxes and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Accrued Liabilities Current [Abstract]
Schedule of Accrued Expenses, Accrued Income Taxes and Other Current Liabilities	Accrued expenses, accrued income taxes and other current liabilities consist of the following: At September 30, 2020 At December 31, 2019 Accrued bonus $ 8,841 $ 8,637 Accrued commissions 2,824 3,153 Other accrued expenses, accrued income taxes and other current liabilities 6,213 6,472 Total $ 17,878 $ 18,262

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2020
Restructuring And Related Activities [Abstract]
Summary of Restructuring Accrual Activity for Employee Severance and Related Benefits Expense	The following table summarizes restructuring accrual activity for employee severance and related benefits expense for the nine months ended September 30, 2020: Employee Severance and Related Benefits Balance at December 31, 2019 $ — Charges 3,248 Cash disbursements (2,581 ) Noncash settlements (667 ) Balance at September 30, 2020 $ —

Stock-based Compensation (Table

Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock-based Compensation Expense by Award Type	Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Options $ — $ 35 $ 17 $ 130 Restricted stock units 11,030 8,726 34,617 25,260 Total stock-based compensation expense $ 11,030 $ 8,761 $ 34,634 $ 25,390
Summary of Allocation of Stock-based Compensation Expense	Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Cost of revenue $ 57 $ 92 $ 241 $ 268 Sales and marketing expense 2,450 2,520 8,206 7,392 Product, technology, and development expense 5,140 3,938 15,861 11,118 General and administrative expense 3,383 2,211 10,326 6,612 Total stock-based compensation expense $ 11,030 $ 8,761 $ 34,634 $ 25,390

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Reconciliation of Numerator and Denominator Used in Calculation of Basic and Diluted Net Income Per Share	The following table presents a reconciliation of the numerator and denominator used in the calculation of basic and diluted net income per share: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net income $ 32,563 $ 10,384 $ 52,390 $ 28,975 Denominator: Weighted-average number of shares of common stock used in computing net income per share attributable to common stockholders — basic 113,027,995 111,662,949 112,707,003 111,257,271 Dilutive effect of share equivalents resulting from stock options 632,581 1,052,758 701,176 1,232,754 Dilutive effect of share equivalents resulting from unvested restricted stock units 306,287 649,068 324,437 899,670 Weighted-average number of shares of common stock used in computing net income per share — diluted 113,966,863 113,364,775 113,732,616 113,389,695 Net income per share attributable to common stockholders: Basic $ 0.29 $ 0.09 $ 0.46 $ 0.26 Diluted $ 0.29 $ 0.09 $ 0.46 $ 0.26
Schedule of Potentially Dilutive Common Stock Equivalents Excluded from Calculation of Diluted Weighted-average Shares Outstanding	The following potentially dilutive common stock equivalents have been excluded from the calculation of diluted weighted-average shares outstanding for the three and nine months ended September 30, 2020 and 2019, as their effect would have been anti-dilutive for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Restricted stock units outstanding 2,577,713 1,421,473 2,893,491 1,191,286

Segment and Geographic Inform_2

Segment and Geographic Information (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Summary of Operations by Segment and Geographical Area	Information regarding the Company’s operations by segment and geographical area is presented as follows: Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Segment revenue: United States $ 138,412 $ 141,637 $ 376,164 $ 407,050 International 9,060 8,825 23,734 23,713 Total revenue $ 147,472 $ 150,462 $ 399,898 $ 430,763 Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Segment income (loss) from operations: United States $ 46,462 $ 19,956 $ 82,061 $ 51,456 International (2,895 ) (10,252 ) (17,766 ) (30,769 ) Total income from operations $ 43,567 $ 9,704 $ 64,295 $ 20,687

Organization and Business Des_2

Organization and Business Description - Additional Information (Details)	9 Months Ended
	Sep. 30, 2020Segment
Organization Consolidation And Presentation Of Financial Statements [Abstract]
State of incorporation	DE
Date of incorporation	Jun. 26, 2015
Number of reportable segments	2

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020USD ($)Customer	Sep. 30, 2019Customer	Sep. 30, 2020USD ($)Customer	Sep. 30, 2019USD ($)Customer	Dec. 31, 2019USD ($)Customer
Summary Of Significant Accounting Policies [Line Items]
Description of significant off-balance sheet risk			The Company has no significant off‑balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements.
Allowance for doubtful accounts	$ 610		$ 610		$ 240
Bad debt expense			1,742	$ 695
Allowance for doubtful accounts write offs, net			$ 1,372
ASU 2017-04
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true		true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020		Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect	true		true
Change in accounting principle, accounting standards update, transition option elected			carg:AccountingStandardsUpdate201704ProspectiveMember
ASU 2016-13
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true		true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020		Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect	true		true
Change in accounting principle, accounting standards update, transition option elected			carg:AccountingStandardsUpdate201613ProspectiveMember
Sales Revenue, Net | Concentration of Credit Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk, percentage	10.00%	10.00%	10.00%	10.00%
Number of major customers | Customer	0	0	0	0
Net Accounts Receivable | Advertising Customers
Summary Of Significant Accounting Policies [Line Items]
Unbilled accounts receivable	$ 6,869		$ 6,869		$ 8,880
Net Accounts Receivable | Concentration of Credit Risk
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer			2		1
Net Accounts Receivable | Concentration of Credit Risk | Customer Two
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk, percentage			10.00%
Net Accounts Receivable | Concentration of Credit Risk | Customer One
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk, percentage			10.00%		18.00%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Changes in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Accounting Policies [Abstract]
Balance at Beginning of Period	$ 240
Provision for doubtful accounts	1,742	$ 695
Write–offs, Net of Recoveries	(1,372)
Balance at End of Period	$ 610

Revenue Recognition - Summary o

Revenue Recognition - Summary of Revenue from Contracts with Customers by Geographical Region and by Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation Of Revenue [Line Items]
Revenue	$ 147,472	$ 150,462	$ 399,898	$ 430,763
Marketplace Subscription Revenue
Disaggregation Of Revenue [Line Items]
Revenue	129,953	135,542	351,772	385,481
Advertising and Other Revenue
Disaggregation Of Revenue [Line Items]
Revenue	17,519	14,920	48,126	45,282
United States
Disaggregation Of Revenue [Line Items]
Revenue	138,412	141,637	376,164	407,050
United States | Marketplace Subscription Revenue
Disaggregation Of Revenue [Line Items]
Revenue	121,814	127,807	330,295	365,180
United States | Advertising and Other Revenue
Disaggregation Of Revenue [Line Items]
Revenue	16,598	13,830	45,869	41,870
International
Disaggregation Of Revenue [Line Items]
Revenue	9,060	8,825	23,734	23,713
International | Marketplace Subscription Revenue
Disaggregation Of Revenue [Line Items]
Revenue	8,139	7,735	21,477	20,301
International | Advertising and Other Revenue
Disaggregation Of Revenue [Line Items]
Revenue	$ 921	$ 1,090	$ 2,257	$ 3,412

Revenue Recognition - Additiona

Revenue Recognition - Additional Information (Details) - USD ($)	1 Months Ended	2 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2020	May 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation Of Revenue [Line Items]
Performance obligation unsatisfied			$ 15,600		$ 15,600
Revenue recognized			$ 8,195,000	$ 8,479,000	$ 9,984,000	$ 8,811,000
All Marketplace Subscriptions
Disaggregation Of Revenue [Line Items]
Percentage fee reduction on marketplace subscription services		50.00%
United States
Disaggregation Of Revenue [Line Items]
Percentage fee reduction on marketplace subscription services	20.00%
Canada
Disaggregation Of Revenue [Line Items]
Percentage fee reduction on marketplace subscription services	20.00%
United Kingdom
Disaggregation Of Revenue [Line Items]
Percentage fee reduction on marketplace subscription services	50.00%

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details) - USD ($)	Jan. 16, 2020	Sep. 30, 2020	Sep. 30, 2020
Business Acquisition [Line Items]
Acquisition-related costs incurred		$ 0	$ 1,000,000
Product, Technology, and Development
Business Acquisition [Line Items]
Acquisition-related costs incurred			500,000
General and Administrative
Business Acquisition [Line Items]
Acquisition-related costs incurred			300,000
Sales and Marketing
Business Acquisition [Line Items]
Acquisition-related costs incurred			200,000
Autolist, Inc | San Francisco, California
Business Acquisition [Line Items]
Business acquisition date	Jan. 16, 2020
Payments to acquire business	$ 21,100,000
Amount held in escrow	$ 2,200,000
Acquisition-related costs incurred		$ 1,400,000	$ 1,400,000

Acquisitions - Summary of Preli

Acquisitions - Summary of Preliminary Purchase Price Allocation (Details) - Autolist, Inc $ in Thousands	Jan. 16, 2020USD ($)	[1]
Business Acquisition [Line Items]
Cash and cash equivalents, Adjusted Fair Value at Date of Acquisition	$ 50
Restricted cash, Adjusted Fair Value at Date of Acquisition	220
Accounts receivable, Adjusted Fair Value at Date of Acquisition	1,862
Intangible assets, Adjusted Fair Value at Date of Acquisition	7,600	[2]
Goodwill, Adjusted Fair Value at Date of Acquisition	12,477	[3]
Operating lease right-of-use assets, Adjusted Fair Value at Date of Acquisition	2,169
Other assets, net, Adjusted Fair Value at Date of Acquisition	162
Accounts payable and accrued expenses, Adjusted Fair Value at Date of Acquisition	(358)
Operating lease liabilities - current, Adjusted Fair Value at Date of Acquisition	(446)
Operating lease liabilities - non-current, Adjusted Fair Value at Date of Acquisition	(1,723)
Deferred tax liabilities, Adjusted Fair Value at Date of Acquisition	(687)	[4]
Total purchase price, Adjusted Fair Value at Date of Acquisition	$ 21,326
[1]	The Company refined its estimates of the fair value of certain accounts included within the preliminary purchase price allocation, which resulted in an immaterial adjustment to accounts receivable, cash paid, deferred tax liability and goodwill.
[2]	Identifiable definite-lived intangible assets were comprised of brand, developed technology, and customer relationships of $5,600, $1,200, and $800, respectively, with estimated useful lives of 9 years, 3 years, and 3 years, respectively, which will be amortized on a straight-line basis over their estimated useful lives. The fair value of the brand has been estimated using the multi-period excess earnings method which is a variation of the income approach. The fair value of the developed technology and customer relationships has been estimated using a cost approach, which assesses the cost to redevelop the app and technology, and relationships, respectively.
[3]	The goodwill represents the excess value of the purchase price over net assets acquired. The goodwill in this transaction is primarily attributable to expected consumer traffic growth and shopper connections for dealers across both the CarGurus and Autolist websites, creating additional value for the Company’s premium subscription customers. All goodwill is assigned to the United States reporting segment. The acquisition of Autolist is treated as a stock acquisition for tax purposes and goodwill is not deductible for tax purposes.
[4]	The estimated deferred tax liability corresponds to the acquired intangible assets which have no tax basis.

Acquisitions - Summary of Pre_2

Acquisitions - Summary of Preliminary Purchase Price Allocation (Parenthetical) (Details) - Autolist, Inc - USD ($) $ in Thousands	Jan. 16, 2020	Sep. 30, 2020
Brand
Business Acquisition [Line Items]
Intangible assets	$ 5,600
Estimated useful lives	9 years	9 years
Developed Technology
Business Acquisition [Line Items]
Intangible assets	$ 1,200
Estimated useful lives	3 years	3 years
Customer Relationships
Business Acquisition [Line Items]
Intangible assets	$ 800
Estimated useful lives	3 years	3 years

Fair Value of Financial Instr_3

Fair Value of Financial Instruments Including Cash, Cash Equivalents, and Investments - Schedule of Fair Value Levels, Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments:		$ 111,692
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Held-to-maturity, Type [Extensible List]	us-gaap:CertificatesOfDepositMember	us-gaap:CertificatesOfDepositMember
Total	$ 172,427	$ 140,888
Investments:		111,692
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	$ 172,427	$ 29,196
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Held-to-maturity, Type [Extensible List]	us-gaap:CertificatesOfDepositMember	us-gaap:CertificatesOfDepositMember
Total		$ 111,692
Investments:		111,692
Fair Value, Measurements, Recurring | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	$ 172,427	29,196
Fair Value, Measurements, Recurring | Money Market Funds | Quoted Prices in Active Markets for Identical Assets (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	$ 172,427	$ 29,196

Fair Value of Financial Instr_4

Fair Value of Financial Instruments Including Cash, Cash Equivalents, and Investments - Additional Information (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Maturity period of certificates of deposit	1 year	1 year
Maturity of certificates of deposit, description	Certificates of deposit at December 31, 2019 had maturity dates of one year or less.
Liabilities, fair value	$ 0	$ 0
Held to maturity amortized cost	0	111,692,000
Held to maturity fair value	$ 0	$ 111,692,000

Fair Value of Financial Instr_5

Fair Value of Financial Instruments Including Cash, Cash Equivalents, and Investments - Schedule of Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Certificates of deposit due in one year or less, Amortized Cost		$ 111,692
Held to maturity amortized cost	$ 0	111,692
Certificates of deposit due in one year or less, Estimated Fair Value		111,692
Held to maturity fair value	$ 0	$ 111,692

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 52,617	$ 46,105
Less accumulated depreciation and amortization	(25,341)	(18,155)
Property and equipment, net	27,276	27,950
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,057	7,923
Capitalized Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	181	181
Capitalized Website Development
Property Plant And Equipment [Line Items]
Property and equipment, gross	15,451	11,083
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	7,314	6,809
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	20,492	19,507
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,072	524
Finance Lease Right-of-use Assets
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 50	$ 78

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property Plant And Equipment [Line Items]
Depreciation	$ 1,937	$ 1,951	$ 7,367	$ 5,173
Capitalized Website Development
Property Plant And Equipment [Line Items]
Increase (decrease) in property and equipment			$ 4,368

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Summary of Changes in Carrying Value of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Balance at December 31, 2019	$ 15,207
Autolist acquisition	12,477	[1]
Foreign currency translation adjustment	673
Balance at September 30, 2020	$ 28,357
[1]	See Note 4 of the Unaudited Condensed Consolidated Financial Statements included elsewhere in this Quarterly Report.

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Additional Information (Details) - USD ($)	Jan. 16, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Goodwill [Line Items]
Impairment of goodwill as a result of COVID-19				$ 0
Amortization expense of intangible assets		$ 495,000	$ 167,000	1,412,000	$ 486,000
Impairment of intangible assets, finite-lived as a result of COVID-19				$ 0
PistonHeads | Brand
Goodwill [Line Items]
Estimated useful life				11 years
PistonHeads | Customer Relationships
Goodwill [Line Items]
Estimated useful life				3 years
Autolist | Brand
Goodwill [Line Items]
Estimated useful life	9 years			9 years
Autolist | Customer Relationships
Goodwill [Line Items]
Estimated useful life	3 years			3 years
Autolist | Developed Technology
Goodwill [Line Items]
Estimated useful life	3 years			3 years

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Summary of Other Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 12,323	$ 4,569
Accumulated Amortization	2,061	649
Net Carrying Amount	$ 10,262	$ 3,920
Brand
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (years)	8 years 8 months 12 days	10 years
Gross Carrying Amount	$ 9,257	$ 3,524
Accumulated Amortization	995	313
Net Carrying Amount	$ 8,262	$ 3,211
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (years)	1 year 9 months 18 days	2 years
Gross Carrying Amount	$ 1,866	$ 1,045
Accumulated Amortization	782	336
Net Carrying Amount	$ 1,084	$ 709
Developed Technology
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (years)	2 years 3 months 18 days
Gross Carrying Amount	$ 1,200
Accumulated Amortization	284
Net Carrying Amount	$ 916

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Summary of Estimated Amortization Expense of Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Remainder of 2020	$ 484
2021	1,938
2022	1,704
2023	971
2024	953
2025	953
Thereafter	3,259
Net Carrying Amount	$ 10,262	$ 3,920

Accrued Expenses, Accrued Inc_3

Accrued Expenses, Accrued Income Taxes and Other Current Liabilities - Schedule of Accrued Expenses, Accrued Income Taxes and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued Liabilities Current [Abstract]
Accrued bonus	$ 8,841	$ 8,637
Accrued commissions	2,824	3,153
Other accrued expenses, accrued income taxes and other current liabilities	6,213	6,472
Total	$ 17,878	$ 18,262

Restructuring - Additional Info

Restructuring - Additional Information (Details) - Expense Reduction Plan - USD ($)	Apr. 13, 2020	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2020
Restructuring Cost And Reserve [Line Items]
Workforce reduction, percent	13.00%
Employee Severance and Related Benefits Expense
Restructuring Cost And Reserve [Line Items]
Restructuring and related charges		$ 0	$ 3,248,000	$ 3,248,000
Employee Severance and Related Benefits Expense | Sales and Marketing
Restructuring Cost And Reserve [Line Items]
Restructuring and related charges				2,160,000
Employee Severance and Related Benefits Expense | Product, Technology, and Development
Restructuring Cost And Reserve [Line Items]
Restructuring and related charges				737,000
Employee Severance and Related Benefits Expense | Cost of Revenue
Restructuring Cost And Reserve [Line Items]
Restructuring and related charges				207,000
Employee Severance and Related Benefits Expense | General and Administrative
Restructuring Cost And Reserve [Line Items]
Restructuring and related charges				144,000
Employee Severance and Related Benefits Expense | Stock-Based Compensation Expense
Restructuring Cost And Reserve [Line Items]
Restructuring and related charges				667,000
International
Restructuring Cost And Reserve [Line Items]
Write-off of capitalized website development costs and deferred contract costs			$ 1,019,000
Write-off of capitalized website development costs		0		844,000
International | Sales and Marketing
Restructuring Cost And Reserve [Line Items]
Write-off of deferred contract costs				175,000
International | Cost of Revenue
Restructuring Cost And Reserve [Line Items]
Write-off of capitalized website development costs				844,000
International | Employee Severance and Related Benefits Expense
Restructuring Cost And Reserve [Line Items]
Restructuring and related charges		$ 0		$ 756,000

Restructuring - Summary of Rest

Restructuring - Summary of Restructuring Accrual Activity for Employee Severance and Related Benefits Expense (Details) - Expense Reduction Plan - Employee Severance and Related Benefits Expense - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2020
Restructuring Cost And Reserve [Line Items]
Charges	$ 0	$ 3,248	$ 3,248
Cash disbursements			(2,581)
Noncash settlements			$ (667)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Thousands	Sep. 30, 2020USD ($)	Jun. 12, 2020ft²	Jan. 16, 2020ft²	Dec. 31, 2019USD ($)
Commitments And Contingencies [Line Items]
Restricted cash | $	$ 10,877			$ 10,803
Boston, Massachusetts at 1001 Boylston St
Commitments And Contingencies [Line Items]
Operating lease, office space		225,428
San Francisco, California at 332 Pine St
Commitments And Contingencies [Line Items]
Operating lease, office space			6,345

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Stock-based Compensation Expense by Award Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 11,030	$ 8,761	$ 34,634	$ 25,390
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense		35	17	130
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 11,030	$ 8,726	$ 34,617	$ 25,260

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Allocation of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 11,030	$ 8,761	$ 34,634	$ 25,390
Cost of Revenue
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	57	92	241	268
Sales and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	2,450	2,520	8,206	7,392
Product, Technology, and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	5,140	3,938	15,861	11,118
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 3,383	$ 2,211	$ 10,326	$ 6,612

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Capitalized website development and internal-use software costs excluded from stock-based compensation expense	$ 656	$ 324	$ 1,323	$ 950
Total payments for employees' tax obligations to taxing authorities due to net share settlements and for option exercise costs	$ 2,922	$ 4,192	$ 8,708	$ 12,783
Class A Common Stock
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Employee tax withholding requirements and option costs due to net share settlement	111,370	120,943	337,313	345,114

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020shares	Sep. 30, 2019shares	Sep. 30, 2020Voteshares	Sep. 30, 2019shares
Earnings Per Share Basic [Line Items]
Conversion of stock, description			Each share of Class B common stock is convertible into one share of Class A common stock at the option of the holder at any time or automatically upon certain events described in the Company’s amended and restated certificate of incorporation, including on either the death or voluntary termination of the Company’s Chief Executive Officer.
Undistributed earnings ratio used to calculate allocation to class of stock			100.00%
Class A Common Stock
Earnings Per Share Basic [Line Items]
Right to voting			one vote per share
Number of votes entitled to stockholders per share | Vote			1
Conversion of stock | shares	898,655	200,000	1,238,144	200,000
Class B Common Stock
Earnings Per Share Basic [Line Items]
Right to voting			ten votes per share
Number of votes entitled to stockholders per share | Vote			10
Class of share converted to another class			one share of Class A common stock
Conversion of stock | shares			1

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Reconciliation of Numerator and Denominator Used in Calculation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income	$ 32,563	$ 7,131	$ 12,696	$ 10,384	$ 6,007	$ 12,584	$ 52,390	$ 28,975
Denominator:
Weighted-average number of shares of common stock used in computing net income per share attributable to common stockholders — basic	113,027,995			111,662,949			112,707,003	111,257,271
Dilutive effect of share equivalents resulting from stock options	632,581			1,052,758			701,176	1,232,754
Dilutive effect of share equivalents resulting from unvested restricted stock units	306,287			649,068			324,437	899,670
Weighted-average number of shares of common stock used in computing net income per share — diluted	113,966,863			113,364,775			113,732,616	113,389,695
Net income per share attributable to common stockholders:
Basic	$ 0.29			$ 0.09			$ 0.46	$ 0.26
Diluted	$ 0.29			$ 0.09			$ 0.46	$ 0.26

Earnings Per Share - Schedule_2

Earnings Per Share - Schedule of Potentially Dilutive Common Stock Equivalents Excluded from Calculation of Diluted Weighted-average Shares Outstanding (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restricted Stock Units Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive common stock equivalents excluded from calculation of diluted weighted-average shares outstanding	2,577,713	1,421,473	2,893,491	1,191,286

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	Jul. 20, 2020	Mar. 27, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income tax provision (benefit)			$ 11,209	$ 330	$ 13,312	$ (4,783)
Effective income tax rate			25.60%	3.10%	20.30%	(19.80%)
Statutory tax rate			21.00%	21.00%	21.00%	21.00%
Income tax refund received on carryback of net operating loss		$ 3,863
Reduction in gross net operating loss current		18,723
Increase in deferred federal research & development credit		$ 2,645
Limitation on net operating loss to offset taxable income		80.00%
Minimum foreign income tax rate on foreign earnings, percent	90.00%

Segment and Geographic Inform_3

Segment and Geographic Information - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Sep. 30, 2020USD ($)Segment	Dec. 31, 2019USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			2
Assets	$ 460,551,000		$ 460,551,000	$ 393,623,000
Goodwill	28,357,000		28,357,000	15,207,000
Intangible assets	10,262,000		10,262,000	3,920,000
International
Segment Reporting Information [Line Items]
Assets	31,627,000		31,627,000	32,528,000
Goodwill	15,880,000		15,880,000	15,207,000
Intangible assets	3,577,000		3,577,000	$ 3,920,000
Expense Reduction Plan | International
Segment Reporting Information [Line Items]
Write-off of capitalized website development costs or deferred contract costs	0
Expense Reduction Plan | Employee Severance and Related Benefits Expense
Segment Reporting Information [Line Items]
Employee severance and related benefits expense	0	$ 3,248,000	3,248,000
Expense Reduction Plan | Employee Severance and Related Benefits Expense | International
Segment Reporting Information [Line Items]
Employee severance and related benefits expense	0		756,000
Expense Reduction Plan | Employee Severance and Related Benefits Expense | United States
Segment Reporting Information [Line Items]
Employee severance and related benefits expense	$ 0		$ 2,492,000

Segment and Geographic Inform_4

Segment and Geographic Information - Summary of Operations by Segment and Geographical Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment revenue:
Revenue	$ 147,472	$ 150,462	$ 399,898	$ 430,763
Segment income (loss) from operations:
Total income from operations	43,567	9,704	64,295	20,687
United States
Segment revenue:
Revenue	138,412	141,637	376,164	407,050
Segment income (loss) from operations:
Total income from operations	46,462	19,956	82,061	51,456
International
Segment revenue:
Revenue	9,060	8,825	23,734	23,713
Segment income (loss) from operations:
Total income from operations	$ (2,895)	$ (10,252)	$ (17,766)	$ (30,769)