Description of Business and Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2019
Accounting Policies [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Description of Business Pinterest was incorporated in Delaware in 2008 and is headquartered in San Francisco, California. Pinterest is a visual discovery engine that people around the globe use to find the inspiration to create a life they love. We generate revenue by delivering advertising on our website and mobile application. Basis of Presentation and Consolidation We prepared the accompanying condensed consolidated financial statements in accordance with generally accepted accounting principles in the United States ("GAAP"). The condensed consolidated financial statements include the accounts of Pinterest, Inc. and its wholly owned subsidiaries. We have eliminated all intercompany balances and transactions. The condensed consolidated balance sheet as of December 31, 2018 included herein was derived from the audited financial statements as of that date. We have condensed or omitted certain information and notes normally included in complete financial statements prepared in accordance with GAAP. As such, these unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the year ended December 31, 2018, which are included in our prospectus filed pursuant to Rule 424(b) on April 18, 2019. In our opinion, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but they are not necessarily indicative of the results of operations to be expected for the year ending December 31, 2019. Initial Public Offering On April 23, 2019, we closed our initial public offering ("IPO") in which we issued and sold 75,000,000 shares of Class A common stock at $19.00 per share. We received net proceeds of $1,368.0 million after deducting underwriting discounts and commissions and before deducting estimated offering costs of $8.7 million, of which $5.6 million was included in other assets as of March 31, 2019. Immediately prior to the completion of our IPO, all shares of our outstanding redeemable convertible preferred stock and redeemable convertible preferred stock warrants converted into 308,621,636 shares of Class B common stock on a one-for-one basis, and immediately thereafter but still prior to the completion of our IPO, all of our outstanding common stock were reclassified into 456,213,756 shares of Class B common stock on a one-for-one basis. On April 29, 2019, we issued and sold an additional 11,250,000 shares of Class A common stock at $19.00 per share pursuant to the underwriters’ option to purchase additional shares. We received additional net proceeds of $205.2 million after deducting underwriting discounts and commissions. The shares and proceeds from our IPO and the underwriters’ exercise of their option to purchase additional shares are not reflected in the condensed consolidated financial statements as of and for the three months ended March 31, 2019. Stock Split On March 28, 2019, we effected a 1-for-3 reverse split of our capital stock. We have adjusted all share and per share amounts in the accompanying condensed consolidated financial statements and notes to reflect the reverse stock split. Use of Estimates Preparing our condensed consolidated financial statements in conformity with GAAP requires us to make estimates and judgments that affect amounts reported in the condensed consolidated financial statements and accompanying notes. We base these estimates and judgments on historical experience and various other assumptions that we consider reasonable. GAAP requires us to make estimates and assumptions in several areas, including the fair values of financial instruments, assets acquired and liabilities assumed through business combinations, common stock prior to our IPO and share-based awards, and contingencies as well as the collectability of our accounts receivable, the useful lives of our intangible assets and property and equipment, the incremental borrowing rate we use to determine our operating lease liabilities, and revenue recognition, among others. Actual results could differ materially from these estimates and judgments. Segments We operate as a single operating segment. Our chief operating decision maker is our Chief Executive Officer, who reviews financial information presented on a consolidated basis, accompanied by disaggregated information about our revenue, for purposes of making operating decisions, assessing financial performance and allocating resources. Revenue Recognition We generate revenue by delivering ads on our website and mobile application. We recognize revenue only after transferring control of promised goods or services to customers, which occurs when a user clicks on an ad contracted on a cost per click (“CPC”) basis or views an ad contracted on a cost per thousand impressions (“CPM”) basis. We typically bill customers on a CPC or CPM basis, and our payment terms vary by customer type and location. The term between billing and payment due dates is not significant. We occasionally offer customers free ad inventory or measurement studies that demonstrate the effectiveness of their advertising campaigns on our platform. In either case, we recognize revenue only after satisfying our contractual performance obligation. When contracts with our customers contain multiple performance obligations, we allocate the overall transaction price, which is the amount of consideration to which we expect to be entitled in exchange for promised goods or services, to each of the distinct performance obligations based on their relative standalone selling prices. We generally determine standalone selling prices based on the effective price charged per contracted click or impression or based on expected cost plus margin, and we do not disclose the value of unsatisfied performance obligations because the original expected duration of our contracts is generally less than one year. We record sales commissions in sales and marketing expense as incurred because we would amortize these over a period of less than one year. Deferred revenue was not material as of March 31, 2019 and December 31, 2018. Share-Based Compensation We have granted restricted stock units ("RSUs") since March 2015. We measure RSUs based on the fair market value of our common stock on the grant date. RSUs granted under our 2009 Stock Plan (the "2009 Plan") are subject to both a service condition, which is typically satisfied over four years, and a performance condition, which was deemed satisfied upon the pricing of the shares of Class A common stock sold in connection with our IPO. Because the performance condition had not been satisfied as of March 31, 2019, we had not recorded any share-based compensation expense for our RSUs at that date. Had our IPO occurred on March 31, 2019, we would have recorded cumulative share-based compensation expense using the accelerated attribution method for those RSUs for which the service condition had been satisfied at that date and would have begun recording the remaining unrecognized share-based compensation expense over the remainder of the requisite service period. We account for forfeitures as they occur. Valuation of Common Stock and Redeemable Convertible Preferred Stock Warrants Until our IPO, we determined the fair value of our common stock and redeemable convertible preferred stock warrants using the most observable inputs available to us, including recent sales of our stock as well as income and market valuation approaches. The income approach estimates the value of our business based on the future cash flows we expect to generate discounted to their present value using an appropriate discount rate to reflect the risk of achieving the expected cash flows. The market approach estimates the value of our business by applying valuation multiples derived from the observed valuation multiples of comparable public companies to our expected financial results. We used the Probability Weighted Expected Return Method ("PWERM") to allocate the value of our business among our outstanding stock and share-based awards. We applied the PWERM by first defining the range of potential future liquidity outcomes for our business, such as an IPO, and then allocating its value to our outstanding stock and share-based awards based on the relative probability that each outcome will occur. We used the Option Pricing Method to allocate the value of our business to our outstanding stock and share-based awards under the non-IPO outcome we considered within the PWERM. Applying these valuation and allocation approaches involved the use of estimates, judgments, and assumptions that are highly complex and subjective, such as those regarding our expected future revenue, expenses, and cash flows, discount rates, valuation multiples, the selection of comparable public companies, and the probability of future events. Changes in any or all of these estimates and assumptions, or the relationships between these assumptions, impacted our valuation as of each valuation date and may have a material impact on the valuation of our common stock and redeemable convertible preferred stock warrants. Following our IPO, there is an active market for our Class A common stock and the warrants to purchase shares of our redeemable convertible preferred stock are no longer outstanding, so we no longer apply these valuation and allocation approaches. Leases and Operating Lease Incremental Borrowing Rate We lease office space under operating leases with expiration dates through 2033. We determine whether an arrangement constitutes a lease and record lease liabilities and right-of-use assets on our condensed consolidated balance sheets at lease commencement. We measure lease liabilities based on the present value of the total lease payments not yet paid discounted based on the more readily determinable of the rate implicit in the lease or our incremental borrowing rate, which is the estimated rate we would be required to pay for a collateralized borrowing equal to the total lease payments over the term of the lease. We estimate our incremental borrowing rate based on an analysis of publicly traded debt securities of companies with credit and financial profiles similar to our own. We measure right-of-use assets based on the corresponding lease liability adjusted for (i) payments made to the lessor at or before the commencement date, (ii) initial direct costs we incur and (iii) tenant incentives under the lease. We begin recognizing rent expense when the lessor makes the underlying asset available to us, we do not assume renewals or early terminations unless we are reasonably certain to exercise these options at commencement, and we do not allocate consideration between lease and non-lease components. For short-term leases, we record rent expense in our condensed consolidated statements of operations on a straight-line basis over the lease term and record variable lease payments as incurred.

Description of Business and Summary of Significant Accounting Policies

Description of Business

Pinterest was incorporated in Delaware in 2008 and is headquartered in San Francisco, California. Pinterest is a visual discovery engine that people around the globe use to find the inspiration to create a life they love. We generate revenue by delivering advertising on our website and mobile application.

Basis of Presentation and Consolidation

We prepared the accompanying condensed consolidated financial statements in accordance with generally accepted accounting principles in the United States ("GAAP"). The condensed consolidated financial statements include the accounts of Pinterest, Inc. and its wholly owned subsidiaries. We have eliminated all intercompany balances and transactions.

The condensed consolidated balance sheet as of December 31, 2018 included herein was derived from the audited financial statements as of that date. We have condensed or omitted certain information and notes normally included in complete financial statements prepared in accordance with GAAP. As such, these unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the year ended December 31, 2018, which are included in our prospectus filed pursuant to Rule 424(b) on April 18, 2019.

In our opinion, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but they are not necessarily indicative of the results of operations to be expected for the year ending December 31, 2019.

Initial Public Offering

On April 23, 2019, we closed our initial public offering ("IPO") in which we issued and sold 75,000,000 shares of Class A common stock at $19.00 per share. We received net proceeds of $1,368.0 million after deducting underwriting discounts and commissions and before deducting estimated offering costs of $8.7 million, of which $5.6 million was included in other assets as of March 31, 2019. Immediately prior to the completion of our IPO, all shares of our outstanding redeemable convertible preferred stock and redeemable convertible preferred stock warrants converted into 308,621,636 shares of Class B common stock on a one-for-one basis, and immediately thereafter but still prior to the completion of our IPO, all of our outstanding common stock were reclassified into 456,213,756 shares of Class B common stock on a one-for-one basis.

On April 29, 2019, we issued and sold an additional 11,250,000 shares of Class A common stock at $19.00 per share pursuant to the underwriters’ option to purchase additional shares. We received additional net proceeds of $205.2 million after deducting underwriting discounts and commissions.

The shares and proceeds from our IPO and the underwriters’ exercise of their option to purchase additional shares are not reflected in the condensed consolidated financial statements as of and for the three months ended March 31, 2019.

Stock Split

On March 28, 2019, we effected a 1-for-3 reverse split of our capital stock. We have adjusted all share and per share amounts in the accompanying condensed consolidated financial statements and notes to reflect the reverse stock split.

Use of Estimates

Preparing our condensed consolidated financial statements in conformity with GAAP requires us to make estimates and judgments that affect amounts reported in the condensed consolidated financial statements and accompanying notes. We base these estimates and judgments on historical experience and various other assumptions that we consider reasonable. GAAP requires us to make estimates and assumptions in several areas, including the fair values of financial instruments, assets acquired and liabilities assumed through business combinations, common stock prior to our IPO and share-based awards, and contingencies as well as the collectability of our accounts receivable, the useful lives of our intangible assets and property and equipment, the incremental borrowing rate we use to determine our operating lease liabilities, and revenue recognition, among others. Actual results could differ materially from these estimates and judgments.

Segments

We operate as a single operating segment. Our chief operating decision maker is our Chief Executive Officer, who reviews financial information presented on a consolidated basis, accompanied by disaggregated information about our revenue, for purposes of making operating decisions, assessing financial performance and allocating resources.

Revenue Recognition

We generate revenue by delivering ads on our website and mobile application. We recognize revenue only after transferring control of promised goods or services to customers, which occurs when a user clicks on an ad contracted on a cost per click (“CPC”) basis or views an ad contracted on a cost per thousand impressions (“CPM”) basis. We typically bill customers on a CPC or CPM basis, and our payment terms vary by customer type and location. The term between billing and payment due dates is not significant.

We occasionally offer customers free ad inventory or measurement studies that demonstrate the effectiveness of their advertising campaigns on our platform. In either case, we recognize revenue only after satisfying our contractual performance obligation. When contracts with our customers contain multiple performance obligations, we allocate the overall transaction price, which is the amount of consideration to which we expect to be entitled in exchange for promised goods or services, to each of the distinct performance obligations based on their relative standalone selling prices. We generally determine standalone selling prices based on the effective price charged per contracted click or impression or based on expected cost plus margin, and we do not disclose the value of unsatisfied performance obligations because the original expected duration of our contracts is generally less than one year.

We record sales commissions in sales and marketing expense as incurred because we would amortize these over a period of less than one year.

Deferred revenue was not material as of March 31, 2019 and December 31, 2018.

Share-Based Compensation

We have granted restricted stock units ("RSUs") since March 2015. We measure RSUs based on the fair market value of our common stock on the grant date. RSUs granted under our 2009 Stock Plan (the "2009 Plan") are subject to both a service condition, which is typically satisfied over four years, and a performance condition, which was deemed satisfied upon the pricing of the shares of Class A common stock sold in connection with our IPO. Because the performance condition had not been satisfied as of March 31, 2019, we had not recorded any share-based compensation expense for our RSUs at that date. Had our IPO occurred on March 31, 2019, we would have recorded cumulative share-based compensation expense using the accelerated attribution method for those RSUs for which the service condition had been satisfied at that date and would have begun recording the remaining unrecognized share-based compensation expense over the remainder of the requisite service period.

We account for forfeitures as they occur.

Valuation of Common Stock and Redeemable Convertible Preferred Stock Warrants

Until our IPO, we determined the fair value of our common stock and redeemable convertible preferred stock warrants using the most observable inputs available to us, including recent sales of our stock as well as income and market valuation approaches. The income approach estimates the value of our business based on the future cash flows we expect to generate discounted to their present value using an appropriate discount rate to reflect the risk of achieving the expected cash flows. The market approach estimates the value of our business by applying valuation multiples derived from the observed valuation multiples of comparable public companies to our expected financial results.

We used the Probability Weighted Expected Return Method ("PWERM") to allocate the value of our business among our outstanding stock and share-based awards. We applied the PWERM by first defining the range of potential future liquidity outcomes for our business, such as an IPO, and then allocating its value to our outstanding stock and share-based awards based on the relative probability that each outcome will occur. We used the Option Pricing Method to allocate the value of our business to our outstanding stock and share-based awards under the non-IPO outcome we considered within the PWERM.

Applying these valuation and allocation approaches involved the use of estimates, judgments, and assumptions that are highly complex and subjective, such as those regarding our expected future revenue, expenses, and cash flows, discount rates, valuation multiples, the selection of comparable public companies, and the probability of future events. Changes in any or all of these estimates and assumptions, or the relationships between these assumptions, impacted our valuation as of each valuation date and may have a material impact on the valuation of our common stock and redeemable convertible preferred stock warrants.

Following our IPO, there is an active market for our Class A common stock and the warrants to purchase shares of our redeemable convertible preferred stock are no longer outstanding, so we no longer apply these valuation and allocation approaches.

Leases and Operating Lease Incremental Borrowing Rate

We lease office space under operating leases with expiration dates through 2033. We determine whether an arrangement constitutes a lease and record lease liabilities and right-of-use assets on our condensed consolidated balance sheets at lease commencement. We measure lease liabilities based on the present value of the total lease payments not yet paid discounted based on the more readily determinable of the rate implicit in the lease or our incremental borrowing rate, which is the estimated rate we would be required to pay for a collateralized borrowing equal to the total lease payments over the term of the lease. We estimate our incremental borrowing rate based on an analysis of publicly traded debt securities of companies with credit and financial profiles similar to our own. We measure right-of-use assets based on the corresponding lease liability adjusted for (i) payments made to the lessor at or before the commencement date, (ii) initial direct costs we incur and (iii) tenant incentives under the lease. We begin recognizing rent expense when the lessor makes the underlying asset available to us, we do not assume renewals or early terminations unless we are reasonably certain to exercise these options at commencement, and we do not allocate consideration between lease and non-lease components.

For short-term leases, we record rent expense in our condensed consolidated statements of operations on a straight-line basis over the lease term and record variable lease payments as incurred.