The Trade Desk, Inc. (TTD) 10-Q 8 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	TTD
Entity Registrant Name	THE 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
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		39,834,865
Class B common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		5,299,496

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 173,446	$ 207,232
Short-term investments	123,082
Accounts receivable, net	835,958	834,764
Prepaid expenses and other current assets	26,641	14,527
TOTAL CURRENT ASSETS	1,159,127	1,056,523
Property and equipment, net	47,734	33,046
Operating lease assets	177,276
Deferred income taxes	8,460	8,460
Other assets, non-current	22,442	19,843
TOTAL ASSETS	1,415,039	1,117,872
Current liabilities:
Accounts payable	647,547	669,147
Accrued expenses and other current liabilities	40,553	44,844
Operating lease liabilities	15,938
TOTAL CURRENT LIABILITIES	704,038	713,991
Operating lease liabilities, non-current	167,668
Other liabilities, non-current	7,941	9,314
TOTAL LIABILITIES	879,647	723,305
Commitments and contingencies (Note 9)
STOCKHOLDERS’ EQUITY
Preferred stock, par value $0.000001; 100,000 shares authorized, zero shares issued and outstanding as of September 30, 2019 and December 31, 2018
Common stock, par value $0.000001 Class A, 1,000,000 shares authorized; 39,810 and 36,822 shares issued and outstanding as of September 30, 2019 and December 31, 2018, respectively Class B, 95,000 shares authorized; 5,311 and 7,042 shares issued and outstanding as of September 30, 2019 and December 31, 2018, respectively	0	0
Additional paid-in capital	353,899	270,447
Retained earnings	181,493	124,120
TOTAL STOCKHOLDERS’ EQUITY	535,392	394,567
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 1,415,039	$ 1,117,872

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
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	39,810,000	36,822,000
Common stock, shares outstanding	39,810,000	36,822,000
Class B common stock
Common stock
Common stock, authorized shares	95,000,000	95,000,000
Common stock, shares issued	5,311,000	7,042,000
Common stock, shares outstanding	5,311,000	7,042,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 164,203	$ 118,825	$ 445,114	$ 316,826
Type of Revenue [Extensible List]	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember
Operating expenses:
Platform operations	$ 39,932	$ 29,344	$ 108,913	$ 78,842
Type of Cost, Good or Service [Extensible List]	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember
Sales and marketing	$ 36,142	$ 23,287	$ 89,951	$ 60,007
Technology and development	29,185	22,621	83,949	59,806
General and administrative	37,017	21,310	102,755	59,816
Total operating expenses	142,276	96,562	385,568	258,471
Income from operations	21,927	22,263	59,546	58,355
Other expense (income):
Interest expense (income), net	(1,480)	(237)	(3,763)	(113)
Foreign currency exchange (gain) loss, net	(412)	395	784	2,035
Total other expense (income), net	(1,892)	158	(2,979)	1,922
Income before income taxes	23,819	22,105	62,525	56,433
Provision for income taxes	4,397	1,813	5,152	7,728
Net income	$ 19,422	$ 20,292	$ 57,373	$ 48,705
Earnings per share:
Basic	$ 0.43	$ 0.47	$ 1.29	$ 1.15
Diluted	$ 0.40	$ 0.44	$ 1.20	$ 1.07
Weighted average shares outstanding:
Basic	44,771	42,721	44,363	42,178
Diluted	48,037	46,576	47,728	45,460

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings
Balance at beginning of period at Dec. 31, 2017	$ 245,583		$ 209,603	$ 35,980
Balance at beginning of period (in shares) at Dec. 31, 2017		41,641
Exercise of common stock options	1,212		1,212
Exercise of common stock options (in shares)		415
Stock-based compensation	7,427		7,427
Restricted stock award grants, net of forfeitures and shares withheld for taxes	(361)		(361)
Restricted stock award grants, net of forfeitures and shares withheld for taxes (in shares)		13
Net income	9,070			9,070
Balance at end of period at Mar. 31, 2018	262,931		217,881	45,050
Balance at end of period (in shares) at Mar. 31, 2018		42,069
Balance at beginning of period at Dec. 31, 2017	245,583		209,603	35,980
Balance at beginning of period (in shares) at Dec. 31, 2017		41,641
Net income	48,705
Balance at end of period at Sep. 30, 2018	337,014		252,329	84,685
Balance at end of period (in shares) at Sep. 30, 2018		43,185
Balance at beginning of period at Mar. 31, 2018	262,931		217,881	45,050
Balance at beginning of period (in shares) at Mar. 31, 2018		42,069
Exercise of common stock options	1,997		1,997
Exercise of common stock options (in shares)		365
Stock-based compensation	9,872		9,872
Issuance of common stock under employee stock purchase plan	7,014		7,014
Issuance of common stock under employee stock purchase plan (in shares)		392
Restricted stock award grants, net of forfeitures and shares withheld for taxes	(183)		(183)
Restricted stock award grants, net of forfeitures and shares withheld for taxes (in shares)		28
Net income	19,343			19,343
Balance at end of period at Jun. 30, 2018	300,974		236,581	64,393
Balance at end of period (in shares) at Jun. 30, 2018		42,854
Exercise of common stock options	3,956		3,956
Exercise of common stock options (in shares)		330
Stock-based compensation	11,851		11,851
Restricted stock award grants, net of forfeitures and shares withheld for taxes	(59)		(59)
Restricted stock award grants, net of forfeitures and shares withheld for taxes (in shares)		1
Net income	20,292			20,292
Balance at end of period at Sep. 30, 2018	337,014		252,329	84,685
Balance at end of period (in shares) at Sep. 30, 2018		43,185
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
Stock-based compensation	16,324		16,324
Restricted stock award grants, net of forfeitures and shares withheld for taxes	(1,146)		(1,146)
Restricted stock award grants, net of forfeitures and shares withheld for taxes (in shares)		23
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
Balance at end of period (in shares) at Sep. 30, 2019	535,392	45,121	353,899	181,493
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
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
Restricted stock award grants, net of forfeitures and shares withheld for taxes	(2,488)		(2,488)
Restricted stock award grants, net of forfeitures and shares withheld for taxes (in shares)		7
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
Stock-based compensation	19,923		19,923
Restricted stock award grants, net of forfeitures and shares withheld for taxes	(1,110)		$ (1,110)
Restricted stock award grants, net of forfeitures and shares withheld for taxes (in shares)		2
Net income	19,422			$ 19,422
Balance at end of period at Sep. 30, 2019	$ 535,392
Balance at end of period (in shares) at Sep. 30, 2019	535,392	45,121	353,899	181,493

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
OPERATING ACTIVITIES:
Net income	$ 57,373	$ 48,705
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	15,246	8,107
Stock-based compensation	56,368	27,958
Bad debt expense	1,647	1,727
Noncash lease expense	15,394
Other	(2,945)	2,396
Changes in operating assets and liabilities:
Accounts receivable	(2,739)	(44,736)
Prepaid expenses and other assets	(19,024)	(10,597)
Accounts payable	(21,401)	(2,804)
Accrued expenses and other liabilities	(3,178)	7,789
Operating lease liabilities	(8,468)
Net cash provided by operating activities	88,273	38,545
INVESTING ACTIVITIES:
Purchases of property and equipment	(21,659)	(10,383)
Capitalized software development costs	(3,849)	(4,340)
Purchases of investments	(178,179)
Maturities of investments	55,819
Net cash used in investing activities	(147,868)	(14,723)
FINANCING ACTIVITIES:
Repayment on line of credit		(27,000)
Payment of debt financing costs	(6)
Proceeds from exercise of stock options	21,911	7,165
Proceeds from employee stock purchase plan	8,648	7,014
Taxes paid related to net settlement of restricted stock awards	(4,744)	(602)
Net cash provided by (used in) financing activities	25,809	(13,423)
(Decrease) increase in cash and cash equivalents	(33,786)	10,399
Cash and cash equivalents—Beginning of period	207,232	155,950
Cash and cash equivalents—End of period	173,446	166,349
SUPPLEMENTAL CASH FLOW INFORMATION:
Capitalized assets financed by accounts payable	1,968	6,624
Tenant improvements paid by lessor		1,017
Asset retirement obligation	3,543	386
Stock-based compensation included in capitalized software development costs	1,269	$ 1,192
Cash paid for amounts included in the measurement of lease liabilities included in operating cash flows	12,268
Right-of-use assets obtained in exchange for operating lease liabilities	$ 147,682

Nature of Operations

Nature of Operations	9 Months Ended
	Sep. 30, 2019
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 (CTV).

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
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, 2018 was derived from audited financial statements but does not include all disclosures required by GAAP. On January 1, 2019, the Company adopted Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) , Leases using the modified retrospective adoption approach. The Company elected the transition option provided by Leases (Topic 842): Targeted Improvements . The impact on the Company’s consolidated statements of income and cash flows was not material. Except for the adoption of ASC 842, there have been no changes to the Company’s accounting policies and these unaudited interim condensed consolidated financial statements have been prepared on a basis consistent with that used to prepare the Company’s audited annual consolidated financial statements for the year ended December 31, 2018, and include, in the opinion of management, all adjustments, consisting of normal recurring items, necessary for the fair statement of the condensed consolidated financial statements. The results of operations for the three and nine months ended September 30, 2019 are not necessarily indicative of the results expected for the full year ending December 31, 2019. 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. Operating Leases ROU Assets represent the Company’s right to control the use of an identified asset for a period of time, or term, in exchange for consideration, and Lease Liabilities represent its obligation to make lease payments arising from the aforementioned right. The Company determines if an arrangement is, or contains, a lease at the inception date, and the Company measures and records a non-current ROU Asset and corresponding Lease Liabilities, classified as current and non-current, on its consolidated balance sheet at the lease commencement date for all leases except for short-term leases with a term of 12 months or less. ROU Assets and Lease Liabilities are initially recorded based on the present value of lease payments over the lease term, which may include options to extend or terminate the lease when it is reasonably certain at the commencement date that such options will be exercised. As the rate implicit for each of the Company’s leases is not readily determinable, the Company uses its incremental borrowing rate, based on the information available at the lease commencement date in determining the present value of its expected lease payments. The ROU Asset also includes any initial direct costs and any lease payments made prior to the lease commencement date and is reduced by any lease incentives received. The ROU Asset is amortized on a straight-line basis as the operating lease cost over the lease term on the consolidated statements of income. ROU Asset amortization, referred to as noncash lease expense, along with the change in the operating lease liabilities are separately presented within the cash flows from operating activities on the consolidated statements of cash flows. ASC 842 provides various optional transition practical expedients. Upon transition to ASC 842, the Company elected the use of the package of practical expedients to not reassess: whether a contract is or contains a lease, lease classification and indirect costs. The Company did not elect the hindsight practical expedient in transition. The Company has elected to not separate lease and non-lease components. Refer to Note 5—Leases for additional information. Revision of Cash and Cash Equivalents and Accounts Payable The Company identified an error in its classification of cash and cash equivalents and accounts payable balances at June 30, 2019 of $23.0 million related to certain bank overdrafts. This error had the effect of understating reported cash and cash equivalents and accounts payable by that amount, and accordingly, current assets, total assets, current liabilities, and total liabilities were also understated by an equivalent amount. It also resulted in an understatement of net cash provided by operating activities in the same amount. If corrected, the amounts reported in the 2019 second quarter Form 10-Q would have been as follows: cash and cash equivalents of $153.6 million, accounts payable of $639.2 million, current assets of $1,107.0 million, total assets of $1,262.4 million, current liabilities of $693.5 million, total liabilities of $770.2 million and net cash provided by operating activities of $43.8 million. The Company determined that this error was not material to the previously issued financial statements, and it will revise these amounts in its Quarterly Report on Form 10-Q for the reporting period ended June 30, 2020. Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments - Credit Losses, in April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments . These ASUs provide supplemental guidance and clarification to ASU 2016-13 and must be adopted concurrently with the adoption of ASU 2016-13, cumulatively referred to as “Topic 326.” Topic 326 is In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement-Disclosure Framework (Topic 820).

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2019
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, 2019 2018 2019 2018 Numerator: Net income $ 19,422 $ 20,292 $ 57,373 $ 48,705 Denominator: Weighted-average shares outstanding—basic 44,771 42,721 44,363 42,178 Effect of dilutive securities: Options to purchase common stock 2,762 3,239 2,871 2,780 Employee stock purchase plan shares 141 270 135 273 Restricted stock 363 346 359 229 Weighted-average shares outstanding—diluted 48,037 46,576 47,728 45,460 Basic EPS $ 0.43 $ 0.47 $ 1.29 $ 1.15 Diluted EPS $ 0.40 $ 0.44 $ 1.20 $ 1.07 Anti-dilutive equity awards under stock-based award plans excluded from the determination of diluted EPS 163 167 163 167

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-Term Investments	9 Months Ended
	Sep. 30, 2019
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, 2019 Cash and Cash Short-Term Equivalents Investments Total Cash $ 39,704 — $ 39,704 Level 1: Money market funds 118,510 — 118,510 Level 2: Commercial paper 14,232 25,844 40,076 Corporate debt securities 1,000 69,152 70,152 U.S. government and agency securities — 28,086 28,086 Total $ 173,446 $ 123,082 $ 296,528 As of December 31, 2018 Cash and Cash Equivalents Cash $ 35,087 Level 1: Money market funds 14,145 Time deposits 158,000 Total $ 207,232 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, 2019 Due in one year $ 107,221 Due in one to two years 15,861 Total $ 123,082

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Note 5—Leases The Company has operating leases for its offices. Its leases have remaining lease terms of up to 11 years, some of which include options to extend the leases for up to 5 years, and some of which include options to terminate the leases within 1 year with proper notification. ROU Assets and Lease Liabilities are recorded based on the present value of lease payments over the lease term, which includes the minimum unconditional term of the lease, and may include options to extend or terminate the lease when it is reasonably certain at the commencement date that such options will be exercised. The decision to include these options involves consideration of the Company’s overall growth plans, as well as other strategic requirements. As the rate implicit for each of its leases is not readily determinable, the Company uses its incremental borrowing rate, based on the information available at the lease commencement date, for each of its leases in determining the present value of its expected lease payments. The Company’s incremental borrowing rate is determined by analyzing and combining an applicable risk-free rate, a financial spread adjustment and any lease specific adjustment. Certain leases contain provisions for property-related costs that are variable in nature for which the Company is responsible, including common area maintenance and other property operating services. These costs are calculated based on a variety of factors including property values, tax and utility rates, property services fees, and other factors. The Company records rent expense for operating leases, some of which have escalating rent payments, on a straight-line basis over the lease term. The components of lease expense for the three and nine months ended September 30, 2019 were as follows (in thousands): Three Months Ended Nine Months Ended September 30, 2019 September 30, 2019 Operating lease cost $ 8,547 $ 19,089 Short-term lease cost 491 1,373 Variable lease cost 654 1,836 Sublease income (271 ) (827 ) Total lease cost $ 9,421 $ 21,471 Supplemental information related to leases as of September 30, 2019 was as follows: Weighted average remaining lease term 8.8 years Weighted average discount rate 4.5% Maturities of lease commitments as of September 30, 2019 were as follows (in thousands): Year Amount Remainder of 2019 $ 4,556 2020 10,601 2021 38,462 2022 34,916 2023 32,241 Thereafter 181,843 Total undiscounted lease commitments 302,619 Less: commitments for leases not yet commenced (71,977 ) Less: interest (47,036 ) Present value of lease liabilities 183,606 Less: operating lease liabilities, current (15,938 ) Operating lease liabilities, non-current $ 167,668 As of December 31, 2018, the Company’s non-cancelable minimum lease commitments were as follows (in thousands): Year Amount (1) 2019 $ 13,419 2020 18,746 2021 29,054 2022 23,786 2023 20,902 Thereafter 119,109 Total $ 225,016 (1) Includes non-cancelable minimum lease payments of $183.5 million for leases executed in 2018 that the Company plans to occupy in 2019.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	Note 6—Stock-Based Compensation Stock-Based Compensation Expense Stock-based compensation expense recorded in the condensed consolidated statements of operations was as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2019 2018 2019 2018 Platform operations $ 1,507 $ 1,234 $ 3,894 $ 3,137 Sales and marketing 5,036 3,033 13,094 7,757 Technology and development 7,146 4,013 18,579 8,905 General and administrative 5,753 3,137 20,801 8,159 Total $ 19,442 $ 11,417 $ 56,368 $ 27,958 Stock Options The following summarizes stock option activity: Shares Under Option (in thousands) Weighted- Average Exercise Price Outstanding as of December 31, 2018 4,630 $ 37.03 Granted 681 164.08 Exercised (1,072 ) 20.38 Cancelled (131 ) 66.79 Outstanding as of September 30, 2019 4,108 $ 61.47 Exercisable as of September 30, 2019 1,797 $ 31.01 On January 1, 2019, 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: Shares (in thousands) Weighted- Average Grant Date Fair Value Unvested as of December 31, 2018 518 $ 65.14 Granted 107 161.61 Vested (81 ) 65.12 Forfeited (40 ) 54.94 Unvested as of September 30, 2019 504 $ 86.44 Employee Stock Purchase Plan (“ESPP”) Stock-based compensation expense related to the ESPP totaled $7.3 million and $4.4 million for the three months ended September 30, 2019 and 2018, respectively. Stock-based compensation expense related to the ESPP totaled $17.7 million and $11.0 million for the nine months ended September 30, 2019 and 2018, respectively. On January 1, 2019, the number of shares available for issuance under the Company’s Employee Stock Purchase Plan was increased by 0.4 million shares in accordance with plan provisions.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Note 7—Income Taxes In determining the interim provision for income taxes, the Company uses the annual estimated effective tax rate applied to the actual year-to-date income and adds the tax effects of any discrete items in the reporting period in which they occur. For each of the three months ended September 30, 2019 and 2018, there were benefits associated with stock-based awards of $7.7 million. For the nine months ended September 30, 2019 and 2018, the provision for income taxes included $28.0 million and $14.2 million, respectively, of benefits associated with stock-based awards. For the nine months ended September 30, 2019, and 2018, the Company’s effective tax rate differed from the United States federal statutory tax rate of 21% primarily due to state and foreign taxes, nondeductible stock-based compensation and the impact of tax benefits associated with stock-based awards. There were no material changes to the Company’s unrecognized tax benefits during the nine months ended September 30, 2019, 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, 2019
Segments Geographical Areas [Abstract]
Geographic Information	Note 8—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, 2019 2018 2019 2018 US $ 641,555 $ 479,489 $ 1,754,261 $ 1,282,178 International 109,463 89,255 303,018 242,519 Total $ 751,018 $ 568,744 $ 2,057,279 $ 1,524,697 Property and equipment, net and operating lease assets presented by principal geographic area, were as follows (in thousands): September 30, 2019 December 31, 2018 (1) US $ 141,721 $ 25,887 International 83,289 7,159 Total $ 225,010 $ 33,046 (1) As a result of the Company’s adoption of ASC 842 on January 1, 2019, the December 31, 2018 balance excludes operating lease assets. Refer to Note 2 —

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 9— Commitments and Contingencies As of September Refer to Note 5 — Leases for additional information regarding lease commitments. As of September 30, 2019, the Company has 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 Remainder of 2019 $ 30,162 2020 32,111 2021 30,629 2022 30,248 2023 30,000 Thereafter 50,000 $ 203,150 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. In the ordinary course of business, demands have been made upon the Company to provide indemnification under such agreements, but the Company is not aware of any claims that could have a material effect on the Company’s balance sheet, statement of operations or statement of cash flows. Accordingly, no amounts for any obligation have been recorded at September 30, 2019 . 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 at-will. The Company may be required to accelerate the vesting of certain equity awards 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, 2019
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.
Operating Leases	Operating Leases ROU Assets represent the Company’s right to control the use of an identified asset for a period of time, or term, in exchange for consideration, and Lease Liabilities represent its obligation to make lease payments arising from the aforementioned right. The Company determines if an arrangement is, or contains, a lease at the inception date, and the Company measures and records a non-current ROU Asset and corresponding Lease Liabilities, classified as current and non-current, on its consolidated balance sheet at the lease commencement date for all leases except for short-term leases with a term of 12 months or less. ROU Assets and Lease Liabilities are initially recorded based on the present value of lease payments over the lease term, which may include options to extend or terminate the lease when it is reasonably certain at the commencement date that such options will be exercised. As the rate implicit for each of the Company’s leases is not readily determinable, the Company uses its incremental borrowing rate, based on the information available at the lease commencement date in determining the present value of its expected lease payments. The ROU Asset also includes any initial direct costs and any lease payments made prior to the lease commencement date and is reduced by any lease incentives received. The ROU Asset is amortized on a straight-line basis as the operating lease cost over the lease term on the consolidated statements of income. ROU Asset amortization, referred to as noncash lease expense, along with the change in the operating lease liabilities are separately presented within the cash flows from operating activities on the consolidated statements of cash flows. ASC 842 provides various optional transition practical expedients. Upon transition to ASC 842, the Company elected the use of the package of practical expedients to not reassess: whether a contract is or contains a lease, lease classification and indirect costs. The Company did not elect the hindsight practical expedient in transition. The Company has elected to not separate lease and non-lease components. Refer to Note 5—Leases for additional information.
Revision of Cash and Cash Equivalents and Accounts Payable	Revision of Cash and Cash Equivalents and Accounts Payable The Company identified an error in its classification of cash and cash equivalents and accounts payable balances at June 30, 2019 of $23.0 million related to certain bank overdrafts. This error had the effect of understating reported cash and cash equivalents and accounts payable by that amount, and accordingly, current assets, total assets, current liabilities, and total liabilities were also understated by an equivalent amount. It also resulted in an understatement of net cash provided by operating activities in the same amount. If corrected, the amounts reported in the 2019 second quarter Form 10-Q would have been as follows: cash and cash equivalents of $153.6 million, accounts payable of $639.2 million, current assets of $1,107.0 million, total assets of $1,262.4 million, current liabilities of $693.5 million, total liabilities of $770.2 million and net cash provided by operating activities of $43.8 million. The Company determined that this error was not material to the previously issued financial statements, and it will revise these amounts in its Quarterly Report on Form 10-Q for the reporting period ended June 30, 2020.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments - Credit Losses, in April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments . These ASUs provide supplemental guidance and clarification to ASU 2016-13 and must be adopted concurrently with the adoption of ASU 2016-13, cumulatively referred to as “Topic 326.” Topic 326 is In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement-Disclosure Framework (Topic 820).

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	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, 2019 2018 2019 2018 Numerator: Net income $ 19,422 $ 20,292 $ 57,373 $ 48,705 Denominator: Weighted-average shares outstanding—basic 44,771 42,721 44,363 42,178 Effect of dilutive securities: Options to purchase common stock 2,762 3,239 2,871 2,780 Employee stock purchase plan shares 141 270 135 273 Restricted stock 363 346 359 229 Weighted-average shares outstanding—diluted 48,037 46,576 47,728 45,460 Basic EPS $ 0.43 $ 0.47 $ 1.29 $ 1.15 Diluted EPS $ 0.40 $ 0.44 $ 1.20 $ 1.07 Anti-dilutive equity awards under stock-based award plans excluded from the determination of diluted EPS 163 167 163 167

Cash, Cash Equivalents and Sh_2

Cash, Cash Equivalents and Short-Term Investments (Tables)	9 Months Ended
	Sep. 30, 2019
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, 2019 Cash and Cash Short-Term Equivalents Investments Total Cash $ 39,704 — $ 39,704 Level 1: Money market funds 118,510 — 118,510 Level 2: Commercial paper 14,232 25,844 40,076 Corporate debt securities 1,000 69,152 70,152 U.S. government and agency securities — 28,086 28,086 Total $ 173,446 $ 123,082 $ 296,528 As of December 31, 2018 Cash and Cash Equivalents Cash $ 35,087 Level 1: Money market funds 14,145 Time deposits 158,000 Total $ 207,232
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, 2019 Due in one year $ 107,221 Due in one to two years 15,861 Total $ 123,082

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Summary of Components of Lease Expense	The components of lease expense for the three and nine months ended September 30, 2019 were as follows (in thousands): Three Months Ended Nine Months Ended September 30, 2019 September 30, 2019 Operating lease cost $ 8,547 $ 19,089 Short-term lease cost 491 1,373 Variable lease cost 654 1,836 Sublease income (271 ) (827 ) Total lease cost $ 9,421 $ 21,471
Summary of Supplemental Information Related to Leases	Supplemental information related to leases as of September 30, 2019 was as follows: Weighted average remaining lease term 8.8 years Weighted average discount rate 4.5%
Summary of Maturities of Lease and Non-cancellable Minimum Lease Commitments	Maturities of lease commitments as of September 30, 2019 were as follows (in thousands): Year Amount Remainder of 2019 $ 4,556 2020 10,601 2021 38,462 2022 34,916 2023 32,241 Thereafter 181,843 Total undiscounted lease commitments 302,619 Less: commitments for leases not yet commenced (71,977 ) Less: interest (47,036 ) Present value of lease liabilities 183,606 Less: operating lease liabilities, current (15,938 ) Operating lease liabilities, non-current $ 167,668 As of December 31, 2018, the Company’s non-cancelable minimum lease commitments were as follows (in thousands): Year Amount (1) 2019 $ 13,419 2020 18,746 2021 29,054 2022 23,786 2023 20,902 Thereafter 119,109 Total $ 225,016 (1) Includes non-cancelable minimum lease payments of $183.5 million for leases executed in 2018 that the Company plans to occupy in 2019.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Stock-Based Compensation Expense by Operating Expense Category	Stock-based compensation expense recorded in the condensed consolidated statements of operations was as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2019 2018 2019 2018 Platform operations $ 1,507 $ 1,234 $ 3,894 $ 3,137 Sales and marketing 5,036 3,033 13,094 7,757 Technology and development 7,146 4,013 18,579 8,905 General and administrative 5,753 3,137 20,801 8,159 Total $ 19,442 $ 11,417 $ 56,368 $ 27,958
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, 2018 4,630 $ 37.03 Granted 681 164.08 Exercised (1,072 ) 20.38 Cancelled (131 ) 66.79 Outstanding as of September 30, 2019 4,108 $ 61.47 Exercisable as of September 30, 2019 1,797 $ 31.01
Summary of Nonvested Restricted Stock Activity	The following summarizes Restricted Stock activity: Shares (in thousands) Weighted- Average Grant Date Fair Value Unvested as of December 31, 2018 518 $ 65.14 Granted 107 161.61 Vested (81 ) 65.12 Forfeited (40 ) 54.94 Unvested as of September 30, 2019 504 $ 86.44

Geographic Information (Tables)

Geographic Information (Tables)	9 Months Ended
	Sep. 30, 2019
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, 2019 2018 2019 2018 US $ 641,555 $ 479,489 $ 1,754,261 $ 1,282,178 International 109,463 89,255 303,018 242,519 Total $ 751,018 $ 568,744 $ 2,057,279 $ 1,524,697
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, 2019 December 31, 2018 (1) US $ 141,721 $ 25,887 International 83,289 7,159 Total $ 225,010 $ 33,046 (1) As a result of the Company’s adoption of ASC 842 on January 1, 2019, the December 31, 2018 balance excludes operating lease assets. Refer to Note 2 —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Schedule of Non-Cancelable Contractual Commitments of Obligations	As of September Refer to Note 5 — Leases for additional information regarding lease commitments. As of September 30, 2019, the Company has 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 Remainder of 2019 $ 30,162 2020 32,111 2021 30,629 2022 30,248 2023 30,000 Thereafter 50,000 $ 203,150

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended	9 Months Ended
	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease, right-of-use assets		$ 177,276
Operating lease, liabilities		183,606
Cash and cash equivalents		173,446	$ 166,349		$ 207,232	$ 155,950
Accounts payable		647,547			669,147
Current assets		1,159,127			1,056,523
Total assets		1,415,039			1,117,872
Current liabilities		704,038			713,991
Total liabilities		879,647			$ 723,305
Net cash provided by operating activities		$ 88,273	$ 38,545
Restatement Adjustment
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cash and cash equivalents	$ 153,600
Accounts payable	639,200
Current assets	1,107,000
Total assets	1,262,400
Current liabilities	693,500
Total liabilities	770,200
Net cash provided by operating activities	43,800
Cash and Cash Equivalents and Accounts Payable
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Prior period reclassification adjustment	$ 23,000
ASU 2016-02
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease, right-of-use assets				$ 41,000
Operating lease, liabilities				$ 47,000

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies - Operating Leases (Detail)	9 Months Ended
	Sep. 30, 2019
Maximum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Short-term leases term excluded from calculation of ROU and lease liabilities	12 months

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019USD ($)Class$ / sharesshares	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2018USD ($)$ / sharesshares	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Sep. 30, 2019USD ($)Class$ / sharesshares	Sep. 30, 2018USD ($)$ / sharesshares
Earnings Per Share
Number of classes of common stock | Class	2						2
Numerator:
Net income | $	$ 19,422	$ 27,800	$ 10,151	$ 20,292	$ 19,343	$ 9,070	$ 57,373	$ 48,705
Denominator:
Weighted-average shares outstanding—basic	44,771			42,721			44,363	42,178
Effect of dilutive securities:
Options to purchase common stock	2,762			3,239			2,871	2,780
Employee stock purchase plan shares	141			270			135	273
Restricted stock	363			346			359	229
Weighted-average shares outstanding—diluted	48,037			46,576			47,728	45,460
Basic EPS | $ / shares	$ 0.43			$ 0.47			$ 1.29	$ 1.15
Diluted EPS | $ / shares	$ 0.40			$ 0.44			$ 1.20	$ 1.07
Anti-dilutive equity awards under stock-based award plans excluded from the determination of diluted EPS	163			167			163	167

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, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	$ 173,446	$ 207,232	$ 166,349	$ 155,950
Short-Term Investments	123,082
Available For Sale
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	173,446	207,232
Short-Term Investments	123,082
Total	296,528
Available For Sale | Cash
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	39,704	35,087
Total	39,704
Available For Sale | Level 1 | Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	118,510	14,145
Total	118,510
Available For Sale | Level 1 | Time Deposits
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents		$ 158,000
Available For Sale | Level 2 | Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	14,232
Short-Term Investments	25,844
Total	40,076
Available For Sale | Level 2 | Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Cash and cash equivalents	1,000
Short-Term Investments	69,152
Total	70,152
Available For Sale | Level 2 | U.S. Government and Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Short-Term Investments	28,086
Total	$ 28,086

Cash, Cash Equivalents and Sh_4

Cash, Cash Equivalents and Short - Schedule of Contractual Maturities of Short-Term Investments (Detail) $ in Thousands	Sep. 30, 2019USD ($)
Available For Sale Securities Debt Maturities Fair Value [Abstract]
Due in one year	$ 107,221
Due in one to two years	15,861
Total	$ 123,082

Leases - Additional Information

Leases - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lease term description	leases have remaining lease terms of up to 11 years, some of which include options to extend the leases for up to 5 years, and some of which include options to terminate the leases within 1 year with proper notification.
Remaining lease term	11 years
Lessee, operating lease, existence of option to extend	true
Options to extend the leases	up to 5 years
Lessee, operating lease, existence of option to terminate	true
Options to terminate the leases	within 1 year

Leases - Summary of Components

Leases - Summary of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lease Cost [Abstract]
Operating lease cost	$ 8,547	$ 19,089
Short-term lease cost	491	1,373
Variable lease cost	654	1,836
Sublease income	(271)	(827)
Total lease cost	$ 9,421	$ 21,471

Leases - Summary of Supplementa

Leases - Summary of Supplemental Information Related to Leases (Detail)	Sep. 30, 2019
Leases [Abstract]
Weighted average remaining lease term	8 years 9 months 18 days
Weighted average discount rate	4.50%

Leases - Summary of Maturities

Leases - Summary of Maturities of Lease and Non-cancellable Minimum Lease Commitments (Detail) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Operating Lease Liabilities Payments Due [Abstract]
Remainder of 2019		$ 4,556
2019	[1]		$ 13,419
2020		10,601	18,746	[1]
2021		38,462	29,054	[1]
2022		34,916	23,786	[1]
2023		32,241	20,902	[1]
Thereafter		181,843	119,109	[1]
Total undiscounted lease commitments		302,619	$ 225,016	[1]
Less: commitments for leases not yet commenced		(71,977)
Less: interest		(47,036)
Present value of lease liabilities		183,606
Less: operating lease liabilities, current		(15,938)
Operating lease liabilities, non-current		$ 167,668
[1]	Includes non-cancelable minimum lease payments of $183.5 million for leases executed in 2018 that the Company plans to occupy in 2019.

Leases - Summary of Maturitie_2

Leases - Summary of Maturities of Lease and Non-cancellable Minimum Lease Commitments (Parenthetical) (Detail) $ in Millions	Dec. 31, 2018USD ($)
Operating Lease Liabilities Payments Due [Abstract]
Non-cancelable minimum lease payments for leases	$ 183.5

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense by Operating Expense Category (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	$ 19,442	$ 11,417	$ 56,368	$ 27,958
Platform operations
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	1,507	1,234	3,894	3,137
Sales and marketing
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	5,036	3,033	13,094	7,757
Technology and development
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	7,146	4,013	18,579	8,905
General and administrative
Stock-based compensation expense, by operating expense category
Stock-based compensation expense	$ 5,753	$ 3,137	$ 20,801	$ 8,159

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options (Detail) - Stock Options - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2019
Shares Under Option
Outstanding at the beginning of the period (in shares)	4,630
Granted (in shares)	681
Exercised (in shares)	(1,072)
Cancelled (in shares)	(131)
Outstanding at the end of the period (in shares)	4,108
Exercisable as of September 30, 2019	1,797
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 37.03
Granted (in dollars per share)	164.08
Exercised (in dollars per share)	20.38
Cancelled (in dollars per share)	66.79
Outstanding at the end of the period (in dollars per share)	61.47
Exercisable as of September 30, 2019	$ 31.01

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Options - Additional Information (Detail) shares in Millions	Jan. 01, 2019shares
2016 Incentive Award Plan
Stock-Based Compensation
Number of additional shares authorized for grant	1.8

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Nonvested Restricted Stock Activity (Detail) shares in Thousands	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Unvested, Shares, beginning balance | shares	518
Granted, Shares | shares	107
Vested, Shares | shares	(81)
Forfeited, Shares | shares	(40)
Unvested, Shares, ending balance | shares	504
Unvested, Weighted-Average Grant Date Fair Value Per Share, beginning balance | $ / shares	$ 65.14
Granted, Weighted-Average Grant Date Fair Value Per Share | $ / shares	161.61
Vested, Weighted-Average Grant Date Fair Value Per Share | $ / shares	65.12
Forfeited, Weighted-Average Grant Date Fair Value Per Share | $ / shares	54.94
Unvested, Weighted-Average Grant Date Fair Value Per Share, ending balance | $ / shares	$ 86.44

Stock-Based Compensation - ESPP

Stock-Based Compensation - ESPP - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions	Jan. 01, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock-Based Compensation
Stock-based compensation expense		$ 19,442	$ 11,417	$ 56,368	$ 27,958
ESPP
Stock-Based Compensation
Stock-based compensation expense		$ 7,300	$ 4,400	$ 17,700	$ 11,000
Number of additional shares authorized for grant	0.4

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Benefits associated with stock-based awards	$ 7.7	$ 7.7	$ 28	$ 14.2
Federal tax at statutory rate (as a percent)			21.00%	21.00%

Geographical Information - Gros

Geographical Information - Gross Billings, Based on Billing Address of Clients or Client Affiliates (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues From External Customers And Long Lived Assets [Line Items]
Gross Billings	$ 751,018	$ 568,744	$ 2,057,279	$ 1,524,697
UNITED STATES
Revenues From External Customers And Long Lived Assets [Line Items]
Gross Billings	641,555	479,489	1,754,261	1,282,178
International
Revenues From External Customers And Long Lived Assets [Line Items]
Gross Billings	$ 109,463	$ 89,255	$ 303,018	$ 242,519

Geographical Information - Prop

Geographical Information - Property and Equipment, Net and Operating Lease Assets, Presented by Principal Geographic Area (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	[1]
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	$ 225,010	$ 33,046
UNITED STATES
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	141,721	25,887
International
Revenues From External Customers And Long Lived Assets [Line Items]
Property and equipment, net and operating lease assets	$ 83,289	$ 7,159
[1]	As a result of the Company’s adoption of ASC 842 on January 1, 2019, the December 31, 2018 balance excludes operating lease assets. Refer to Note 2 —

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Non-Cancelable Contractual Commitments of Obligations (Detail) $ in Thousands	Sep. 30, 2019USD ($)
Contractual obligations
Remainder of 2019	$ 30,162
2020	32,111
2021	30,629
2022	30,248
2023	30,000
Thereafter	50,000
Total	$ 203,150

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Detail)	Sep. 30, 2019USD ($)
Indemnifications
Guarantees and Indemnifications
Recorded obligation	$ 0