The Trade Desk, Inc. (TTD) 10-Q 6 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 30, 2020
Document 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
Trading Symbol	TTD
Entity Registrant Name	TRADE DESK, INC.
Entity Central Index Key	0001671933
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	001-37879
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-1887399
Entity Address, Address Line One	42 N. Chestnut Street
Entity Address, City or Town	Ventura
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	93001
City Area Code	805
Local Phone Number	585-3434
Title of 12(b) Security	Class A Common Stock, par value $0.000001 per share
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Class A common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		41,948,956
Class B common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		5,015,339

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 434,371	$ 130,876
Short-term investments, net of allowance for credit losses of $11 and $0 as of September 30, 2020 and December 31, 2019, respectively	122,909	124,112
Accounts receivable, net of allowance for credit losses of $7,182 and $3,920 as of September 30, 2020 and December 31, 2019, respectively	1,139,860	1,166,376
Prepaid expenses and other current assets	58,847	27,857
TOTAL CURRENT ASSETS	1,755,987	1,449,221
Property and equipment, net	111,862	64,012
Operating lease assets	202,172	173,449
Deferred income taxes	39,928	18,950
Other assets, non-current	28,479	23,129
TOTAL ASSETS	2,138,428	1,728,761
Current liabilities:
Accounts payable	919,694	868,618
Accrued expenses and other current liabilities	57,724	47,178
Operating lease liabilities	34,735	14,577
TOTAL CURRENT LIABILITIES	1,012,153	930,373
Operating lease liabilities, non-current	205,408	174,873
Debt, net	72,000
Other liabilities, non-current	16,240	10,998
TOTAL LIABILITIES	1,305,801	1,116,244
Commitments and contingencies (Note 10)
STOCKHOLDERS’ EQUITY
Preferred stock, par value $0.000001; 100,000 shares authorized, zero shares issued and outstanding as of September 30, 2020 and December 31, 2019
Common stock, par value $0.000001 Class A, 1,000,000 shares authorized; 41,930 and 40,305 shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively Class B, 95,000 shares authorized; 5,015 and 5,171 shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	0	0
Additional paid-in capital	510,017	380,079
Accumulated other comprehensive income	145
Retained earnings	322,465	232,438
TOTAL STOCKHOLDERS’ EQUITY	832,627	612,517
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 2,138,428	$ 1,728,761

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Short-term investments, allowance for credit losses	$ 11	$ 0
Accounts receivable, allowance for credit losses	$ 7,182	$ 3,920
Preferred stock
Preferred stock, par value (in dollars per share)	$ 0.000001	$ 0.000001
Preferred stock, authorized shares	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock
Common stock, par value (in dollars per share)	$ 0.000001	$ 0.000001
Class A common stock
Common stock
Common stock, authorized shares	1,000,000,000	1,000,000,000
Common stock, shares issued	41,930,000	40,305,000
Common stock, shares outstanding	41,930,000	40,305,000
Class B common stock
Common stock
Common stock, authorized shares	95,000,000	95,000,000
Common stock, shares issued	5,015,000	5,171,000
Common stock, shares outstanding	5,015,000	5,171,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 216,113	$ 164,203	$ 516,128	$ 445,114
Type of Revenue [Extensible List]	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember
Operating expenses:
Platform operations	$ 44,826	$ 39,932	$ 127,167	$ 108,913
Type of Cost, Good or Service [Extensible List]	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember
Sales and marketing	$ 44,637	$ 36,142	$ 116,002	$ 89,951
Technology and development	41,079	29,185	117,931	83,949
General and administrative	42,789	37,017	117,252	102,755
Total operating expenses	173,331	142,276	478,352	385,568
Income from operations	42,782	21,927	37,776	59,546
Other expense (income):
Interest expense (income), net	235	(1,480)	(740)	(3,763)
Foreign currency exchange (gain) loss, net	(12)	(412)	1,574	784
Total other expense (income), net	223	(1,892)	834	(2,979)
Income before income taxes	42,559	23,819	36,942	62,525
Provision for (benefit from) income taxes	1,312	4,397	(53,473)	5,152
Net income	$ 41,247	$ 19,422	$ 90,415	$ 57,373
Earnings per share:
Basic	$ 0.89	$ 0.43	$ 1.96	$ 1.29
Diluted	$ 0.84	$ 0.40	$ 1.86	$ 1.20
Weighted average shares outstanding:
Basic	46,582	44,771	46,075	44,363
Diluted	49,220	48,037	48,731	47,728

CONDENSED CONSOLIDATED STATEM_2

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	$ 41,247	$ 19,422	$ 90,415	$ 57,373
Other comprehensive income:
Change in unrealized (loss) gain on available-for-sale investments, net of tax	(129)		145
Comprehensive income	$ 41,118	$ 19,422	$ 90,560	$ 57,373

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings	Retained EarningsCumulative Effect, Period of Adoption, Adjustment
Balance at beginning of period at Dec. 31, 2018	$ 394,567			$ 270,447		$ 124,120
Balance at beginning of period (in shares) at Dec. 31, 2018			43,864
Exercise of common stock options	9,502			9,502
Exercise of common stock options (in shares)			592
Restricted stock, net of forfeitures and shares withheld for taxes	(1,146)			(1,146)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			23
Stock-based compensation	16,324			16,324
Net income	10,151					10,151
Balance at end of period at Mar. 31, 2019	429,398			295,127		134,271
Balance at end of period (in shares) at Mar. 31, 2019			44,479
Balance at beginning of period at Dec. 31, 2018	394,567			270,447		124,120
Balance at beginning of period (in shares) at Dec. 31, 2018			43,864
Net income	57,373
Balance at end of period at Sep. 30, 2019	535,392			353,899		181,493
Balance at end of period (in shares) at Sep. 30, 2019			45,121
Balance at beginning of period at Mar. 31, 2019	429,398			295,127		134,271
Balance at beginning of period (in shares) at Mar. 31, 2019			44,479
Exercise of common stock options	7,473			7,473
Exercise of common stock options (in shares)			284
Restricted stock, net of forfeitures and shares withheld for taxes	(2,488)			(2,488)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			7
Stock-based compensation	21,390			21,390
Issuance of common stock under employee stock purchase plan	8,648			8,648
Issuance of common stock under employee stock purchase plan (in shares)			153
Net income	27,800					27,800
Balance at end of period at Jun. 30, 2019	492,221			330,150		162,071
Balance at end of period (in shares) at Jun. 30, 2019			44,923
Exercise of common stock options	4,936			4,936
Exercise of common stock options (in shares)			196
Restricted stock, net of forfeitures and shares withheld for taxes	(1,110)			(1,110)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			2
Stock-based compensation	19,923			19,923
Net income	19,422					19,422
Balance at end of period at Sep. 30, 2019	535,392			353,899		181,493
Balance at end of period (in shares) at Sep. 30, 2019			45,121
Balance at beginning of period at Dec. 31, 2019	$ 612,517	$ (388)		380,079		232,438	$ (388)
Balance at beginning of period (in shares) at Dec. 31, 2019			45,476
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Exercise of common stock options	$ 19,320			19,320
Exercise of common stock options (in shares)			539
Restricted stock, net of forfeitures and shares withheld for taxes	(4,893)			(4,893)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			20
Stock-based compensation	23,263			23,263
Other comprehensive income	158				$ 158
Net income	24,057					24,057
Balance at end of period at Mar. 31, 2020	674,034			417,769	158	256,107
Balance at end of period (in shares) at Mar. 31, 2020			46,035
Balance at beginning of period at Dec. 31, 2019	612,517	$ (388)		380,079		232,438	$ (388)
Balance at beginning of period (in shares) at Dec. 31, 2019			45,476
Net income	90,415
Balance at end of period at Sep. 30, 2020	832,627			510,017	145	322,465
Balance at end of period (in shares) at Sep. 30, 2020			46,945
Balance at beginning of period at Mar. 31, 2020	674,034			417,769	158	256,107
Balance at beginning of period (in shares) at Mar. 31, 2020			46,035
Exercise of common stock options	22,375			22,375
Exercise of common stock options (in shares)			431
Restricted stock, net of forfeitures and shares withheld for taxes	(2,836)			(2,836)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			61
Stock-based compensation	24,516			24,516
Issuance of common stock under employee stock purchase plan	15,035			15,035
Issuance of common stock under employee stock purchase plan (in shares)			202
Other comprehensive income	116				116
Net income	25,111					25,111
Balance at end of period at Jun. 30, 2020	758,351			476,859	274	281,218
Balance at end of period (in shares) at Jun. 30, 2020			46,729
Exercise of common stock options	12,247			12,247
Exercise of common stock options (in shares)			224
Restricted stock, net of forfeitures and shares withheld for taxes	(6,455)			(6,455)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			(8)
Stock-based compensation	27,366			27,366
Other comprehensive income	(129)				(129)
Net income	41,247					41,247
Balance at end of period at Sep. 30, 2020	$ 832,627			$ 510,017	$ 145	$ 322,465
Balance at end of period (in shares) at Sep. 30, 2020			46,945

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
OPERATING ACTIVITIES:
Net income	$ 90,415	$ 57,373
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	20,777	15,246
Stock-based compensation	73,751	56,368
Allowance for credit losses on accounts receivable	2,722	1,647
Noncash lease expense	24,052	15,394
Deferred income taxes	(20,978)
Other	1,242	(2,945)
Changes in operating assets and liabilities:
Accounts receivable	21,063	(2,739)
Prepaid expenses and other assets	(23,919)	(19,024)
Accounts payable	47,728	(21,401)
Accrued expenses and other liabilities	11,006	(3,178)
Operating lease liabilities	(10,388)	(8,468)
Net cash provided by operating activities	237,471	88,273
INVESTING ACTIVITIES:
Purchases of investments	(127,117)	(178,179)
Maturities of investments	128,315	55,819
Purchases of property and equipment	(57,721)	(21,659)
Capitalized software development costs	(4,246)	(3,849)
Net cash used in investing activities	(60,769)	(147,868)
FINANCING ACTIVITIES:
Proceeds from line of credit	143,000
Repayment on line of credit	(71,000)
Payment of debt financing costs		(6)
Proceeds from exercise of stock options	53,942	21,911
Proceeds from employee stock purchase plan	15,035	8,648
Taxes paid related to net settlement of restricted stock awards	(14,184)	(4,744)
Net cash provided by financing activities	126,793	25,809
Increase (decrease) in cash and cash equivalents	303,495	(33,786)
Cash and cash equivalents—Beginning of period	130,876	207,232
Cash and cash equivalents—End of period	434,371	173,446
SUPPLEMENTAL CASH FLOW INFORMATION:
Capitalized assets financed by accounts payable	12,842	1,968
Asset retirement obligation	1,601	3,543
Stock-based compensation included in capitalized software development costs	1,394	1,269
Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows	17,702	12,268
Right-of-use assets obtained in exchange for operating lease liabilities	$ 52,238	$ 147,682

Nature of Operations

Nature of Operations	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Nature of Operations	Note 1—Nature of Operations The Trade Desk, Inc. (the “Company”) was formed in November 2009 as a Delaware corporation. The Company is headquartered in Ventura, California and has offices in various cities in North America, Europe, Asia and Australia. The Company is a technology company that empowers buyers of advertising by providing a self-service cloud-based platform on which ad buyers can create, manage, and optimize more expressive data-driven digital advertising campaigns across ad formats, including display, video, audio, native, and social, on a multitude of devices, such as computers, mobile devices, and connected TV.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Note 2—Basis of Presentation and Summary of Significant Accounting Policies The accompanying condensed consolidated financial statements were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and are unaudited. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with GAAP have been condensed or omitted. The condensed consolidated balance sheet as of December 31, 2019 was derived from audited financial statements but does not include all disclosures required by GAAP. Except for the adoption of Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments The results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the results expected for the full year ending December 31, 2020. Use of Estimates The preparation of 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 disclosures of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ materially from these estimates. As of September 30, 2020, the impact of the Coronavirus pandemic (“COVID-19”) on our business continues to evolve. As a result, many of our estimates and assumptions, including the allowance for credit losses, consider macro-economic factors in the market, which require increased judgment and carry a higher degree of variability and volatility. As events continue to evolve and additional information becomes available, our estimates may change materially in future periods. Adoption of New Accounting Standard In June 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-13 , which requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. As a result, the Company revised its impairment model to utilize an expected loss methodology in place of an incurred loss methodology related to its marketable securities and allowance for doubtful accounts. The Company adopted ASC 326 on January 1, 2020, using a modified retrospective transition method, which requires a cumulative-effect adjustment, if any, to the opening balance of retained earnings to be recognized on the date of adoption with prior periods not restated. The cumulative-effect adjustment recorded on January 1, 2020, was not material. Accounts Receivable and Allowance for Credit Losses (formerly Allowance for Doubtful Accounts) Accounts receivable are recorded at the invoiced amount, are unsecured and do not bear interest. The Company performs ongoing credit evaluations of its clients and certain advertisers when the Company’s agreements with its clients contain sequential liability terms that provide that the client payments are not due to the Company until the client has received payment from its clients who are advertisers. We maintain an allowance for credit losses for expected uncollectible accounts receivable, which is recorded as an offset to accounts receivable and changes in such are classified as general and administrative expense in the Consolidated Statements of Income. Based on the implementation of CECL during the first quarter of 2020 , the Company considers macro-economic factors and industry specific default rates in the valuation of trade receivables and the related allowance for credit losses . The industry specific default rates are applied to the advertiser’s industry if the receivables are subject to sequential liability or the Company is engaged with the advertiser directly. The services of an outside valuation firm were used to assist in the determination of the macro-economic factors and the industry default rates . For the three and nine months ended September 30, 2020 , our assessment considered business and market disruptions caused by COVID-19 and estimates of credit defaults by industry. Recent Accounting Pronouncements In December 2019, the FASB Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848)

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Earnings Per Share	Note 3—Earnings Per Share The Company has two classes of common stock, Class A and Class B. Basic and diluted earnings per share (“EPS”) attributable to common stockholders for Class A and Class B common stock were the same because they were entitled to the same liquidation and dividend rights. The computation of basic and diluted EPS is as follows (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Numerator: Net income $ 41,247 $ 19,422 $ 90,415 $ 57,373 Denominator: Weighted-average shares outstanding—basic 46,582 44,771 46,075 44,363 Effect of dilutive securities: Options to purchase common stock 2,223 2,762 2,282 2,871 Employee stock purchase plan shares 370 141 293 135 Restricted stock 45 363 81 359 Weighted-average shares outstanding—diluted 49,220 48,037 48,731 47,728 Basic EPS $ 0.89 $ 0.43 $ 1.96 $ 1.29 Diluted EPS $ 0.84 $ 0.40 $ 1.86 $ 1.20 Anti-dilutive equity awards under stock-based award plans excluded from the determination of diluted EPS 188 163 188 163

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-Term Investments	9 Months Ended
	Sep. 30, 2020
Cash Cash Equivalents And Short Term Investments [Abstract]
Cash, Cash Equivalents and Short-Term Investments	Note 4—Cash, Cash Equivalents and Short-Term Investments Cash, cash equivalents and short-term investments in marketable securities were as follows (in thousands): As of September 30, 2020 Cash and Cash Short-Term Equivalents Investments Total Cash $ 135,564 $ — $ 135,564 Level 1: Money market funds 283,606 — 283,606 Level 2: Commercial paper 13,698 28,875 42,573 Corporate debt securities 1,503 59,173 60,676 U.S. government and agency securities — 34,861 34,861 Total $ 434,371 $ 122,909 $ 557,280 As of December 31, 2019 Cash and Cash Short-Term Equivalents Investments Total Cash $ 32,123 $ — $ 32,123 Level 1: Money market funds 45,588 — 45,588 Time deposits 35,000 — 35,000 Level 2: Commercial paper 15,666 24,975 40,641 Corporate debt securities — 78,998 78,998 U.S. government and agency securities 2,499 20,139 22,638 Total $ 130,876 $ 124,112 $ 254,988 The Company’s gross unrealized gains or losses from its short-term investments, recorded at fair value, for the periods presented within this quarterly report were immaterial. The contractual maturities of the Company’s short-term investments are as follows (in thousands): September 30, 2020 Due in one year $ 112,360 Due in one to two years 10,549 Total $ 122,909

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	Note 5—Leases The components of lease expense recorded in the condensed consolidated statements of operations were as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Operating lease cost $ 10,768 $ 8,547 $ 30,848 $ 19,089 Short-term lease cost 228 491 723 1,373 Variable lease cost 1,688 654 4,251 1,836 Sublease income (936 ) (271 ) (2,789 ) (827 ) Total lease cost $ 11,748 $ 9,421 $ 33,033 $ 21,471 Maturities of lease commitments as of September 30, 2020 were as follows (in thousands): Year Amount 2020 (for remaining three months) $ 5,248 2021 52,334 2022 49,788 2023 45,603 2024 37,035 Thereafter 167,800 Total undiscounted lease commitments 357,808 Less: commitments for leases not yet commenced (76,178 ) Less: interest (41,487 ) Present value of lease liabilities 240,143 Less: operating lease liabilities, current (34,735 ) Operating lease liabilities, non-current $ 205,408

Debt

Debt	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Debt	Note 6—Debt Credit Facility As of September 30, 2020, the Company’s outstanding debt balance under the Second Amended and Restated Loan and Security Agreement among the Company and a syndicate of banks, led by Citibank, N.A., as agent (the “Credit Facility”) was $72.0 million, which bore interest at a weighted average annual rate of 1.64%. The Company was in compliance with all covenants as of September 30, 2020. In March 2020, the Company drew down $143.0 million under the Credit Facility as a precautionary measure to provide increased liquidity and preserve financial flexibility in light of the worldwide decline in business activity brought about by COVID-19. Subsequent to March 2020, we repaid $71.0 million from available working capital. Availability under the Credit Facility was $70.8 million as of September 30, 2020. In October 2020, the Company repaid the remaining balance on its Credit Facility.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	Note 7—Stock-Based Compensation Stock-Based Compensation Expense Stock-based compensation expense recorded in the condensed consolidated statements of income was as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Platform operations $ 1,639 $ 1,507 $ 5,459 $ 3,894 Sales and marketing 6,916 5,036 18,549 13,094 Technology and development 7,911 7,146 24,345 18,579 General and administrative 10,386 5,753 25,398 20,801 Total $ 26,852 $ 19,442 $ 73,751 $ 56,368 Stock Options The following summarizes stock option activity: Shares Under Option (in thousands) Weighted- Average Exercise Price Outstanding as of December 31, 2019 4,064 $ 70.74 Granted 292 301.49 Exercised (1,194 ) 45.20 Cancelled (150 ) 123.00 Outstanding as of September 30, 2020 3,012 $ 100.66 Exercisable as of September 30, 2020 1,478 $ 52.22 On January 1, 2020, the number of shares authorized for grant under the Company’s 2016 Incentive Award Plan was increased by 1.8 million shares in accordance with plan provisions. Restricted Stock The following summarizes restricted stock activity: RSU (in thousands) Weighted- Average Grant Date Fair Value Unvested as of December 31, 2019 457 $ 120.65 Granted 347 309.80 Vested (108 ) 126.65 Forfeited (51 ) 158.05 Unvested as of September 30, 2020 645 $ 218.53 Employee Stock Purchase Plan (“ESPP”) Stock-based compensation expense related to the ESPP totaled $3.7 million and $7.3 million for the three months ended September 30, 2020 and 2019, respectively. Stock-based compensation expense related to the ESPP totaled $17.8 million and $17.7 million for the nine months ended September 30, 2020 and 2019, respectively. On January 1, 2020, the number of shares available for issuance under the Company’s ESPP was increased by 0.5 million shares in accordance with plan provisions.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 8—Income Taxes In determining the interim provision for income taxes, the Company utilized the discrete effective tax rate method, as allowed by ASC 740-270-30-18, “Income Taxes – Interim Reporting” For the three months ended September 30, 2020 and 2019, the provision for (benefit from) income taxes included $25.6 million and $7.7 million, respectively, of benefits associated with stock-based awards. For the nine months ended September 30, 2020 and 2019, the provision for (benefit from) income taxes included $98.7 million and $28.0 million, respectively, of benefits associated with stock-based awards. In addition, the income taxes for the nine months ended September 30, 2020 includes an income tax benefit attributable to the expected net operating loss (“NOL”) carryback provided for under the Coronavirus Aid, Relief, and Economic Security Act, or CARES Act. The expected NOL carryback applies to the Company’s 2015-2017 income tax years, in which it paid federal income tax at a 35% tax rate. For the nine months ended September 30, 2020, and 2019, the Company’s effective tax rate differed from the United States federal statutory tax rate of 21% primarily due to tax benefits associated with employee exercises of stock options and vesting of restricted stock units, state taxes, foreign tax rate differences, the federal rate differential on NOL carrybacks, and research and development tax credits. There were no material changes to the Company’s unrecognized tax benefits during the nine months ended September 30, 2020, and the Company does not expect to have any significant changes to unrecognized tax benefits through the end of the fiscal year.

Geographic Information

Geographic Information	9 Months Ended
	Sep. 30, 2020
Segments Geographical Areas [Abstract]
Geographic Information	Note 9—Geographic Information The Company reports revenue net of amounts it pays suppliers for the cost of advertising inventory, third-party data and other add-on features (collectively, “Supplier Features”). The Company generally bills clients for the gross amount of Supplier Features they purchase through its platform and the platform fees, net of allowances (“Gross Billings”). The Company’s accounts receivable are recorded at the amount of Gross Billings for the amounts it is responsible to collect, and accounts payable are recorded at the net amount payable to suppliers. Accordingly, both accounts receivable and accounts payable appear large in relation to revenue reported on a net basis. Gross Billings, based on the billing address of the clients or client affiliates, were as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 U.S. $ 940,055 $ 641,555 $ 2,184,743 $ 1,754,261 International 150,495 109,463 345,921 303,018 Total $ 1,090,550 $ 751,018 $ 2,530,664 $ 2,057,279 Property and equipment, net and operating lease assets presented by principal geographic area, were as follows (in thousands): September 30, 2020 December 31, 2019 U.S. $ 212,064 $ 157,245 International 101,970 80,216 Total $ 314,034 $ 237,461

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 10— Commitments and Contingencies As of September 30, 2020, the Company had non-cancelable contractual commitments of obligations to its hosting services providers, marketing contracts and providers of software as a service, and these commitments were as follows (in thousands): Year Amount 2020 (for remaining three months) $ 16,016 2021 36,580 2022 34,828 2023 30,142 2024 32,500 $ 150,066 As of September 30, 2020, the Company had various non-cancelable operating lease commitments for office space which have been recorded as Lease Liabilities. Refer to Note 5 — Leases for additional information regarding lease commitments. Guarantees and Indemnification In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to clients, vendors, lessors, business partners, and other parties with respect to certain matters, including, but not limited to, losses arising out of breach of such agreements, services to be provided by the Company or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. No demands have been made upon the Company to provide indemnification under such agreements, and thus, there are no claims that the Company is aware of that could have a material effect on the Company’s balance sheet, statement of income or statement of cash flows. Accordingly, no amounts for any obligation have been recorded at September 30, 2020. Litigation From time to time, the Company is subject to various legal proceedings and claims, either asserted or unasserted, that arise in the ordinary course of business. Although the outcome of the various legal proceedings and claims cannot be predicted with certainty, management does not believe that any of these proceedings or other claims will have a material adverse effect on the Company’s business, financial condition, results of operations or cash flows. Employment Contracts The Company has entered into agreements with severance terms with certain employees and officers, all of whom are employed on an at-will basis, subject to certain severance obligations in the event of certain involuntary terminations. The Company may be required to accelerate the vesting of certain stock options in the event of changes in control, as defined, and involuntary terminations.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of 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 disclosures of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ materially from these estimates. As of September 30, 2020, the impact of the Coronavirus pandemic (“COVID-19”) on our business continues to evolve. As a result, many of our estimates and assumptions, including the allowance for credit losses, consider macro-economic factors in the market, which require increased judgment and carry a higher degree of variability and volatility. As events continue to evolve and additional information becomes available, our estimates may change materially in future periods.
Adoption of New Accounting Standard	Adoption of New Accounting Standard In June 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-13 , which requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions and reasonable and supportable forecasts. As a result, the Company revised its impairment model to utilize an expected loss methodology in place of an incurred loss methodology related to its marketable securities and allowance for doubtful accounts. The Company adopted ASC 326 on January 1, 2020, using a modified retrospective transition method, which requires a cumulative-effect adjustment, if any, to the opening balance of retained earnings to be recognized on the date of adoption with prior periods not restated. The cumulative-effect adjustment recorded on January 1, 2020, was not material.
Accounts Receivable and Allowance for Credit Losses (formerly Allowance for Doubtful Accounts)	Accounts Receivable and Allowance for Credit Losses (formerly Allowance for Doubtful Accounts) Accounts receivable are recorded at the invoiced amount, are unsecured and do not bear interest. The Company performs ongoing credit evaluations of its clients and certain advertisers when the Company’s agreements with its clients contain sequential liability terms that provide that the client payments are not due to the Company until the client has received payment from its clients who are advertisers. We maintain an allowance for credit losses for expected uncollectible accounts receivable, which is recorded as an offset to accounts receivable and changes in such are classified as general and administrative expense in the Consolidated Statements of Income. Based on the implementation of CECL during the first quarter of 2020 , the Company considers macro-economic factors and industry specific default rates in the valuation of trade receivables and the related allowance for credit losses . The industry specific default rates are applied to the advertiser’s industry if the receivables are subject to sequential liability or the Company is engaged with the advertiser directly. The services of an outside valuation firm were used to assist in the determination of the macro-economic factors and the industry default rates . For the three and nine months ended September 30, 2020 , our assessment considered business and market disruptions caused by COVID-19 and estimates of credit defaults by industry.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In December 2019, the FASB Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848)

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Computation of Basic and Diluted EPS	The computation of basic and diluted EPS is as follows (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Numerator: Net income $ 41,247 $ 19,422 $ 90,415 $ 57,373 Denominator: Weighted-average shares outstanding—basic 46,582 44,771 46,075 44,363 Effect of dilutive securities: Options to purchase common stock 2,223 2,762 2,282 2,871 Employee stock purchase plan shares 370 141 293 135 Restricted stock 45 363 81 359 Weighted-average shares outstanding—diluted 49,220 48,037 48,731 47,728 Basic EPS $ 0.89 $ 0.43 $ 1.96 $ 1.29 Diluted EPS $ 0.84 $ 0.40 $ 1.86 $ 1.20 Anti-dilutive equity awards under stock-based award plans excluded from the determination of diluted EPS 188 163 188 163

Cash, Cash Equivalents and Sh_2

Cash, Cash Equivalents and Short-Term Investments (Tables)	9 Months Ended
	Sep. 30, 2020
Cash Cash Equivalents And Short Term Investments [Abstract]
Schedule of Cash, Cash Equivalents and Short-term Investments in Marketable Securities	Cash, cash equivalents and short-term investments in marketable securities were as follows (in thousands): As of September 30, 2020 Cash and Cash Short-Term Equivalents Investments Total Cash $ 135,564 $ — $ 135,564 Level 1: Money market funds 283,606 — 283,606 Level 2: Commercial paper 13,698 28,875 42,573 Corporate debt securities 1,503 59,173 60,676 U.S. government and agency securities — 34,861 34,861 Total $ 434,371 $ 122,909 $ 557,280 As of December 31, 2019 Cash and Cash Short-Term Equivalents Investments Total Cash $ 32,123 $ — $ 32,123 Level 1: Money market funds 45,588 — 45,588 Time deposits 35,000 — 35,000 Level 2: Commercial paper 15,666 24,975 40,641 Corporate debt securities — 78,998 78,998 U.S. government and agency securities 2,499 20,139 22,638 Total $ 130,876 $ 124,112 $ 254,988
Schedule of Contractual Maturities of Short-Term Investments	The contractual maturities of the Company’s short-term investments are as follows (in thousands): September 30, 2020 Due in one year $ 112,360 Due in one to two years 10,549 Total $ 122,909

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Summary of Components of Lease Expense	The components of lease expense recorded in the condensed consolidated statements of operations were as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Operating lease cost $ 10,768 $ 8,547 $ 30,848 $ 19,089 Short-term lease cost 228 491 723 1,373 Variable lease cost 1,688 654 4,251 1,836 Sublease income (936 ) (271 ) (2,789 ) (827 ) Total lease cost $ 11,748 $ 9,421 $ 33,033 $ 21,471
Summary of Maturities of Lease Commitments	Maturities of lease commitments as of September 30, 2020 were as follows (in thousands): Year Amount 2020 (for remaining three months) $ 5,248 2021 52,334 2022 49,788 2023 45,603 2024 37,035 Thereafter 167,800 Total undiscounted lease commitments 357,808 Less: commitments for leases not yet commenced (76,178 ) Less: interest (41,487 ) Present value of lease liabilities 240,143 Less: operating lease liabilities, current (34,735 ) Operating lease liabilities, non-current $ 205,408

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Stock-Based Compensation Expense	Stock-based compensation expense recorded in the condensed consolidated statements of income was as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Platform operations $ 1,639 $ 1,507 $ 5,459 $ 3,894 Sales and marketing 6,916 5,036 18,549 13,094 Technology and development 7,911 7,146 24,345 18,579 General and administrative 10,386 5,753 25,398 20,801 Total $ 26,852 $ 19,442 $ 73,751 $ 56,368
Summary of Stock Option Activity	The following summarizes stock option activity: Shares Under Option (in thousands) Weighted- Average Exercise Price Outstanding as of December 31, 2019 4,064 $ 70.74 Granted 292 301.49 Exercised (1,194 ) 45.20 Cancelled (150 ) 123.00 Outstanding as of September 30, 2020 3,012 $ 100.66 Exercisable as of September 30, 2020 1,478 $ 52.22
Summary of Restricted Stock Activity	The following summarizes restricted stock activity: RSU (in thousands) Weighted- Average Grant Date Fair Value Unvested as of December 31, 2019 457 $ 120.65 Granted 347 309.80 Vested (108 ) 126.65 Forfeited (51 ) 158.05 Unvested as of September 30, 2020 645 $ 218.53

Geographic Information (Tables)

Geographic Information (Tables)	9 Months Ended
	Sep. 30, 2020
Segments Geographical Areas [Abstract]
Gross Billings, Based on Billing Address of Clients or Client Affiliates	Gross Billings, based on the billing address of the clients or client affiliates, were as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 U.S. $ 940,055 $ 641,555 $ 2,184,743 $ 1,754,261 International 150,495 109,463 345,921 303,018 Total $ 1,090,550 $ 751,018 $ 2,530,664 $ 2,057,279
Property and Equipment, Net and Operating Lease Assets, Presented by Principal Geographic Area	Property and equipment, net and operating lease assets presented by principal geographic area, were as follows (in thousands): September 30, 2020 December 31, 2019 U.S. $ 212,064 $ 157,245 International 101,970 80,216 Total $ 314,034 $ 237,461

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Schedule of Non-Cancelable Contractual Commitments of Obligations	As of September 30, 2020, the Company had non-cancelable contractual commitments of obligations to its hosting services providers, marketing contracts and providers of software as a service, and these commitments were as follows (in thousands): Year Amount 2020 (for remaining three months) $ 16,016 2021 36,580 2022 34,828 2023 30,142 2024 32,500 $ 150,066

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - ASU No. 2016-13	Sep. 30, 2020
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect	true

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Detail)	Sep. 30, 2020Class
Earnings Per Share
Number of classes of common stock	2

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ 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	$ 41,247	$ 25,111	$ 24,057	$ 19,422	$ 27,800	$ 10,151	$ 90,415	$ 57,373
Denominator:
Weighted-average shares outstanding—basic	46,582			44,771			46,075	44,363
Effect of dilutive securities:
Options to purchase common stock	2,223			2,762			2,282	2,871
Employee stock purchase plan shares	370			141			293	135
Restricted stock	45			363			81	359
Weighted-average shares outstanding—diluted	49,220			48,037			48,731	47,728
Basic EPS	$ 0.89			$ 0.43			$ 1.96	$ 1.29
Diluted EPS	$ 0.84			$ 0.40			$ 1.86	$ 1.20
Anti-dilutive equity awards under stock-based award plans excluded from the determination of diluted EPS	188			163			188	163

Cash, Cash Equivalents and Sh_3

Cash, Cash Equivalents and Short -Term Investments - Schedule of Cash, Cash Equivalents and Short-term Investments in Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	$ 434,371	$ 130,876
Short-Term Investments	122,909	124,112
Available For Sale
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	434,371	130,876
Short-Term Investments	122,909	124,112
Total	557,280	254,988
Available For Sale | Cash
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	135,564	32,123
Total	135,564	32,123
Available For Sale | Level 1 | Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	283,606	45,588
Total	283,606	45,588
Available For Sale | Level 1 | Time Deposits
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents		35,000
Total		35,000
Available For Sale | Level 2 | Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	13,698	15,666
Short-Term Investments	28,875	24,975
Total	42,573	40,641
Available For Sale | Level 2 | Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	1,503
Short-Term Investments	59,173	78,998
Total	60,676	78,998
Available For Sale | Level 2 | U.S. Government and Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents		2,499
Short-Term Investments	34,861	20,139
Total	$ 34,861	$ 22,638

Cash, Cash Equivalents and Sh_4

Cash, Cash Equivalents and Short - Schedule of Contractual Maturities of Short-Term Investments (Detail) $ in Thousands	Sep. 30, 2020USD ($)
Available For Sale Securities Debt Maturities Fair Value [Abstract]
Due in one year	$ 112,360
Due in one to two years	10,549
Total	$ 122,909

Leases - Summary of Components

Leases - Summary of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lease Cost [Abstract]
Operating lease cost	$ 10,768	$ 8,547	$ 30,848	$ 19,089
Short-term lease cost	228	491	723	1,373
Variable lease cost	1,688	654	4,251	1,836
Sublease income	(936)	(271)	(2,789)	(827)
Total lease cost	$ 11,748	$ 9,421	$ 33,033	$ 21,471

Leases - Summary of Maturities

Leases - Summary of Maturities of Lease Commitments (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Operating Lease Liabilities Payments Due [Abstract]
2020 (for remaining three months)	$ 5,248
2021	52,334
2022	49,788
2023	45,603
2024	37,035
Thereafter	167,800
Total undiscounted lease commitments	357,808
Less: commitments for leases not yet commenced	(76,178)
Less: interest	(41,487)
Present value of lease liabilities	240,143
Less: operating lease liabilities, current	(34,735)	$ (14,577)
Operating lease liabilities, non-current	$ 205,408	$ 174,873

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Mar. 31, 2020	Sep. 30, 2020
Long-term debt:
Proceeds from line of credit		$ 143,000
Repayment on line of credit from available working capital		71,000
Second Amended and Restated Loan and Security Agreement
Long-term debt:
Outstanding debt balance		$ 72,000
Credit facility, weighted average annual rate		1.64%
Proceeds from line of credit	$ 143,000
Repayment on line of credit from available working capital		$ 71,000
Availability under the credit facility		$ 70,800

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	$ 26,852	$ 19,442	$ 73,751	$ 56,368
Platform operations
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	1,639	1,507	5,459	3,894
Sales and marketing
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	6,916	5,036	18,549	13,094
Technology and development
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	7,911	7,146	24,345	18,579
General and administrative
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	$ 10,386	$ 5,753	$ 25,398	$ 20,801

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - Stock Options - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2020
Shares Under Option
Outstanding at the beginning of the period (in shares)	4,064
Granted (in shares)	292
Exercised (in shares)	(1,194)
Cancelled (in shares)	(150)
Outstanding at the end of the period (in shares)	3,012
Exercisable as of September 30, 2020	1,478
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 70.74
Granted (in dollars per share)	301.49
Exercised (in dollars per share)	45.20
Cancelled (in dollars per share)	123
Outstanding at the end of the period (in dollars per share)	100.66
Exercisable as of September 30, 2020	$ 52.22

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options - Additional Information (Detail) shares in Millions	Jan. 01, 2020shares
2016 Incentive Award Plan
Stock-Based Compensation
Number of additional shares authorized for grant	1.8

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Restricted Stock Activity (Detail) shares in Thousands	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Unvested, RSU, beginning balance | shares	457
Granted, RSU | shares	347
Vested, RSU | shares	(108)
Forfeited, RSU | shares	(51)
Unvested, RSU, ending balance | shares	645
Unvested, Weighted-Average Grant Date Fair Value Per Share, beginning balance | $ / shares	$ 120.65
Granted, Weighted-Average Grant Date Fair Value Per Share | $ / shares	309.80
Vested, Weighted-Average Grant Date Fair Value Per Share | $ / shares	126.65
Forfeited, Weighted-Average Grant Date Fair Value Per Share | $ / shares	158.05
Unvested, Weighted-Average Grant Date Fair Value Per Share, ending balance | $ / shares	$ 218.53

Stock-Based Compensation - ESPP

Stock-Based Compensation - ESPP - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions	Jan. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock-Based Compensation
Stock-based compensation expense		$ 26,852	$ 19,442	$ 73,751	$ 56,368
ESPP
Stock-Based Compensation
Stock-based compensation expense		$ 3,700	$ 7,300	$ 17,800	$ 17,700
Number of additional shares authorized for grant	0.5

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Provision for (benefit from) income taxes, benefits associated with stock-based awards	$ 25.6	$ 7.7	$ 98.7	$ 28
Federal tax at statutory rate (as a percent)			21.00%	21.00%	35.00%	35.00%	35.00%

Geographic Information - Gross

Geographic Information - Gross Billings, Based on Billing Address of Clients or Client Affiliates (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues From External Customers And Long Lived Assets [Line Items]
Gross Billings	$ 1,090,550	$ 751,018	$ 2,530,664	$ 2,057,279
U.S.
Revenues From External Customers And Long Lived Assets [Line Items]
Gross Billings	940,055	641,555	2,184,743	1,754,261
International
Revenues From External Customers And Long Lived Assets [Line Items]
Gross Billings	$ 150,495	$ 109,463	$ 345,921	$ 303,018

Geographic Information - Proper

Geographic Information - Property and Equipment, Net and Operating Lease Assets, Presented by Principal Geographic Area (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	$ 314,034	$ 237,461
U.S.
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	212,064	157,245
International
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	$ 101,970	$ 80,216

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Non-Cancelable Contractual Commitments of Obligations (Detail) $ in Thousands	Sep. 30, 2020USD ($)
Contractual obligations
2020 (for remaining three months)	$ 16,016
2021	36,580
2022	34,828
2023	30,142
2024	32,500
Total	$ 150,066

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Detail)	Sep. 30, 2020USD ($)
Indemnifications
Commitments and Contingencies
Recorded obligation	$ 0