Block (SQ) 10-K 27 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 22, 2018	Jun. 30, 2017
Class of Stock [Line Items]
Entity Registrant Name	Square, Inc.
Entity Central Index Key	1,512,673
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Public Float			$ 6.4
Class A
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		283,432,014
Class B
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		112,924,272

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 696,474	$ 452,030
Short-term investments	169,576	59,901
Restricted cash	28,805	22,131
Settlements receivable	620,523	321,102
Customer funds	103,042	43,574
Loans held for sale	73,420	42,144
Other current assets	86,454	60,543
Total current assets	1,778,294	1,001,425
Property and equipment, net	91,496	88,328
Goodwill	58,327	57,173
Acquired intangible assets, net	14,334	19,292
Long-term investments	203,667	27,366
Restricted cash	9,802	14,584
Other non-current assets	31,350	3,194
Total assets	2,187,270	1,211,362
Current liabilities:
Accounts payable	16,763	12,602
Customers payable	733,736	431,632
Settlements payable	114,788	51,151
Accrued transaction losses	26,893	20,064
Accrued expenses	52,280	39,543
Other current liabilities	28,367	22,472
Total current liabilities	972,827	577,464
Long-term debt (Note 9)	358,572	0
Other non-current liabilities	69,538	57,745
Total liabilities	1,400,937	635,209
Commitments and contingencies (Note 14)
Stockholders’ equity:
Preferred stock, $0.0000001 par value: 100,000,000 shares authorized at December 31, 2017 and December 31, 2016. None issued and outstanding at December 31, 2017 and December 31, 2016.	0	0
Additional paid-in capital	1,630,386	1,357,381
Accumulated other comprehensive loss	(1,318)	(1,989)
Accumulated deficit	(842,735)	(779,239)
Total stockholders’ equity	786,333	576,153
Total liabilities and stockholders’ equity	2,187,270	1,211,362
Class A
Stockholders’ equity:
Common stock	0	0
Class B
Stockholders’ equity:
Common stock	$ 0	$ 0

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Preferred stock, par value (in USD per share)	$ 0.00	$ 0.00
Preferred stock, shares authorized (in shares)	100,000,000	100,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Class A
Common stock, par value (in USD per share)	$ 0.00	$ 0.00
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	280,400,813	198,746,620
Common stock, shares outstanding (in shares)	280,400,813	198,746,620
Class B
Common stock, par value (in USD per share)	$ 0.00	$ 0.00
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	114,793,262	165,800,756
Common stock, shares outstanding (in shares)	114,793,262	165,800,756

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Hardware revenue	$ 41,415	$ 44,307	$ 16,377
Total net revenue	2,214,253	1,708,721	1,267,118
Cost of Revenue [Abstract]
Hardware costs	62,393	68,562	30,874
Amortization of acquired technology	6,544	8,028	5,639
Total cost of revenue	1,374,947	1,132,683	897,088
Gross profit	839,306	576,038	370,030
Operating expenses:
Product development	321,888	268,537	199,638
Sales and marketing	253,170	173,876	145,618
General and administrative	250,553	251,993	143,466
Transaction, loan and advance losses	67,018	51,235	54,009
Amortization of acquired customer assets	883	850	1,757
Total operating expenses	893,512	746,491	544,488
Operating loss	(54,206)	(170,453)	(174,458)
Interest and other (income) expense, net	8,458	(780)	1,613
Loss before income tax	(62,664)	(169,673)	(176,071)
Provision for income taxes	149	1,917	3,746
Net loss	(62,813)	(171,590)	(179,817)
Deemed dividend on Series E preferred stock	0	0	(32,200)
Net loss attributable to common stockholders	$ (62,813)	$ (171,590)	$ (212,017)
Net loss per share attributable to common stockholders:
Basic (in USD per share)	$ (0.17)	$ (0.50)	$ (1.24)
Diluted (in USD per share)	$ (0.17)	$ (0.50)	$ (1.24)
Weighted-average shares used to compute net loss per share attributable to common stockholders:
Basic (in shares)	379,344	341,555	170,498
Diluted (in shares)	379,344	341,555	170,498
Subscription and services-based
Revenue:
Revenue	$ 252,664	$ 129,351	$ 58,013
Cost of Revenue [Abstract]
Transaction and services-based costs	75,720	43,132	22,470
Customers Other than Starbucks | Transaction-based
Revenue:
Revenue	1,920,174	1,456,160	1,050,445
Cost of Revenue [Abstract]
Transaction and services-based costs	1,230,290	943,200	672,667
Starbucks | Transaction-based
Revenue:
Revenue	0	78,903	142,283
Cost of Revenue [Abstract]
Transaction and services-based costs	$ 0	$ 69,761	$ 165,438

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (62,813)	$ (171,590)	$ (179,817)
Net foreign currency translation adjustments	1,900	(716)	(356)
Net unrealized gain (loss) on revaluation of intercompany loans	385	(11)	(22)
Net unrealized loss on marketable securities	(1,614)	(77)	0
Total comprehensive loss	$ (62,142)	$ (172,394)	$ (180,195)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	IPO	Series E	Convertible preferred stock	Convertible preferred stockSeries E	Class A and B common stock	Class A and B common stockIPO	Additional paid-in capital	Additional paid-in capitalIPO	Accumulated other comprehensive loss	Accumulated deficit
Beginning balance at Dec. 31, 2014	$ 273,672			$ 514,945		$ 0		$ 155,166		$ (807)	$ (395,632)
Beginning balance (in shares) at Dec. 31, 2014				135,252,809		154,603,683
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(179,817)										(179,817)
Shares issued in connection with:
Issuance of stock		$ 245,726	$ 29,952		$ 29,952				$ 245,726
Issuance of stock (in shares)					1,940,058		29,700,000
Conversion of Series A, B, C, D & E preferred stock upon initial public offering to common stock	0			$ (544,897)				544,897
Conversion of Series A, B, C, D & E preferred stock upon initial public offering to common stock (in shares)				(137,192,867)		137,192,867
Deemed dividend on Series E preferred stock	$ 0							32,200			(32,200)
Deemed dividend on Series E preferred stock (in shares)	10,299,696					10,299,696
Exercise of stock options	$ 14,766							14,766
Exercise of stock options (in shares)						5,544,785
Issuance of common stock related to acquisitions	35,776							35,776
Issuance of common stock related to acquisitions (in shares)						3,591,014
Issuance of common stock	0							0
Issuance of common stock (in shares)						3,777
Vesting of early exercised stock options	4,958							4,958
Contribution of common stock	0
Contribution of common stock (in shares)						(5,068,238)
Repurchase of common stock	0
Repurchase of common stock (in shares)						(918,139)
Change in other comprehensive loss	(378)									(378)
Share-based compensation	82,292							82,292
Tax benefit from share-based award activity	1,101							1,101
Ending balance at Dec. 31, 2015	508,048			$ 0		$ 0		1,116,882		(1,185)	(607,649)
Ending balance (in shares) at Dec. 31, 2015				0		334,949,445
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(171,590)										(171,590)
Shares issued in connection with:
Exercise of stock options and warrants	82,438							82,438
Exercise of stock options and warrants (in shares)						24,413,821
Purchases under employee stock purchase plan	14,201							14,201
Purchases under employee stock purchase plan (in shares)						1,852,900
Vesting of restricted stock units	0
Vesting of restricted stock units (in shares)						3,392,726
Vesting of early exercised stock options	2,313							2,313
Cancellation of shares related to business combinations	0
Cancellation of shares related to business combinations (in shares)						(228)
Repurchase of common stock	0
Repurchase of common stock (in shares)						(61,288)
Change in other comprehensive loss	(804)									(804)
Share-based compensation	141,547							141,547
Ending balance at Dec. 31, 2016	576,153			$ 0		$ 0		1,357,381		(1,989)	(779,239)
Ending balance (in shares) at Dec. 31, 2016				0		364,547,376
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(62,813)										(62,813)
Shares issued in connection with:
Exercise of stock options	$ 144,774							144,774
Exercise of stock options (in shares)	24,510,745					24,510,745
Purchases under employee stock purchase plan	$ 17,859							17,859
Purchases under employee stock purchase plan (in shares)						1,670,045
Vesting of restricted stock units	0
Vesting of restricted stock units (in shares)						5,964,153
Vesting of early exercised stock options	661							661
Repurchase of common stock	0
Repurchase of common stock (in shares)						(24,209)
Change in other comprehensive loss	671									671
Share-based compensation	159,509							159,509
Tax withholding related to vesting of restricted stock units	(44,682)							(44,682)
Tax withholding related to vesting of restricted stock units (in shares)						(1,474,035)
Conversion feature of convertible senior notes, due 2022, net of allocated debt issuance costs	83,901							83,901
Purchase of bond hedges in conjunction with issuance of convertible senior notes, due 2022	(92,136)							(92,136)
Sale of warrants in conjunction with issuance of convertible senior notes, due 2022	57,244							57,244
Payment for termination of Starbucks warrant	(54,808)							(54,808)
Ending balance at Dec. 31, 2017	$ 786,333			$ 0		$ 0		$ 1,630,386		$ (1,318)	$ (842,735)
Ending balance (in shares) at Dec. 31, 2017				0		395,194,075

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (62,813)	$ (171,590)	$ (179,817)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	37,279	37,745	27,626
Non-cash interest and other expense	14,421	(49)	270
Share-based compensation	155,836	138,786	82,292
Excess tax benefit from share-based payment activity	0	0	(1,101)
Transaction, loan and advance losses	67,018	51,235	54,009
Deferred provision (benefit) for income taxes	(1,385)	58	26
Changes in operating assets and liabilities:
Settlements receivable	(305,831)	(177,662)	(31,810)
Customer funds	(59,468)	(34,128)	(6,462)
Purchase of loans held for sale	(1,184,630)	(668,976)	(816)
Sales and principal payments of loans held for sale	1,145,314	627,627	21
Other current assets	(26,119)	16,116	(25,841)
Other non-current assets	(3,274)	631	1,220
Accounts payable	4,515	(2,147)	7,831
Customers payable	301,778	206,574	76,009
Settlements payable	63,637	38,046	13,105
Charge-offs to accrued transaction losses	(46,148)	(47,931)	(34,655)
Accrued expenses	12,207	(409)	21,450
Other current liabilities	3,683	6,056	6,655
Other non-current liabilities	11,691	3,149	11,111
Net cash provided by operating activities	127,711	23,131	21,123
Cash flows from investing activities:
Purchase of marketable securities	(544,910)	(164,766)	0
Proceeds from maturities of marketable securities	168,224	43,200	0
Proceeds from sale of marketable securities	89,087	34,222	0
Purchase of property and equipment	(26,097)	(25,433)	(37,432)
Proceeds from sale of property and equipment	0	296	0
Payments for investment in privately held entity	(25,000)	0	0
Payment for acquisition of intangible assets	0	(400)	(1,286)
Business acquisitions, net of cash acquired	(1,915)	(1,360)	(4,500)
Net cash used in investing activities:	(340,611)	(114,241)	(43,218)
Cash flows from financing activities:
Proceeds from issuance of convertible senior notes, net	428,250	0	0
Purchase of convertible senior note hedges	(92,136)	0	0
Proceeds from issuance of warrants	57,244	0	0
Payment for termination of Starbucks warrant	(54,808)	0	0
Proceeds from issuance of preferred stock, net	0	0	29,952
Proceeds from issuance of common stock upon initial public offering, net of offering costs		0	251,257
Payments of offering costs related to initial public offering	0	(5,530)	0
Principal payments on debt	0	0	(30,000)
Payments of debt issuance costs	0	0	(1,387)
Principal payments on capital lease obligation	(1,439)	(168)	0
Proceeds from the exercise of stock options and purchases under the employee stock purchase plan, net	162,504	96,439	13,840
Payments for tax withholding related to vesting of restricted stock units	(44,682)	0	0
Excess tax benefit from share-based payment award	0	0	1,101
Net cash provided by financing activities	454,933	90,741	264,763
Effect of foreign exchange rate on cash and cash equivalents	4,303	(438)	(1,775)
Net increase (decrease) in cash, cash equivalents and restricted cash	246,336	(807)	240,893
Cash, cash equivalents and restricted cash, beginning of the year	488,745	489,552	248,659
Cash, cash equivalents and restricted cash, end of the year	$ 735,081	$ 488,745	$ 489,552

DESCRIPTION OF BUSINESS AND SUM

DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Business Square, Inc. (together with its subsidiaries, Square or the Company) creates tools that help sellers start, run, and grow their businesses. Square enables sellers to accept card payments and also provides reporting and analytics, next-day settlement, and chargeback protection. Square’s point-of-sale software and other business services help sellers manage inventory, locations, and employees; access financing; engage customers; and grow sales. Cash App is an easy way for businesses and individuals to send and receive money and Caviar is a food ordering service for pickup and delivery that helps restaurants reach new customers. Square was founded in 2009 and is headquartered in San Francisco, with offices in the United States, Canada, Japan, Australia, Ireland, and the United Kingdom. Reclassifications and Other Adjustments As a result of the Company’s adoption of Accounting Standards Update (ASU) No. 2016-18, Restricted Cash, on January 1, 2017, the Company reclassified changes in restricted cash balances from investing activities in the statement of cash flows to changes in cash, cash equivalents and restricted cash. For the years ended December 31, 2016 and 2015, $8.5 million and $1.9 million , respectively, was reclassified from cash outflows from investing activities to changes in cash, cash equivalents and restricted cash. During the year ended December 31, 2017, the Company has reclassified certain prior period balances to conform to the current period presentation. In particular the Company has combined the Customer funds obligation and Customers payable into a single caption called Customers payable on the consolidated balance sheet. This classification change was made because both accounts reflect customer amounts that are held by Square that are obligations to the customer. Litigation Settlement On June 8, 2016 , a final, definitive settlement agreement (Settlement Agreement) was entered into by Robert E. Morley, REM Holdings 3, LLC, Jack Dorsey, Jim McKelvey, and the Company. The Settlement Agreement required an aggregate total payment of $50.0 million to plaintiffs, including meaningful contributions by Mr. Dorsey and Mr. McKelvey. The Company made a payment of $48.0 million to plaintiffs and met its obligations under the Settlement Agreement. This amount was classified within general and administrative expenses on the consolidated statements of operations for the year ended December 31, 2016. On June 17, 2016 , the Court entered an Order dismissing the complaints in their entirety, with prejudice. Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) and include the accounts of the Company and its subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, as well as related disclosure of contingent assets and liabilities. Actual results could differ from the Company’s estimates. To the extent that there are material differences between these estimates and actual results, the Company’s financial condition or operating results will be materially affected. The Company bases its estimates on past experience and other assumptions that the Company believes are reasonable under the circumstances, and the Company evaluates these estimates on an ongoing basis. Estimates, judgments, and assumptions in these consolidated financial statements include, but are not limited to, those related to revenue recognition, accrued transaction losses, valuation of the debt component of convertible senior notes, valuation of loans held for sale, goodwill and intangible assets, income and other taxes, and share-based compensation. Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery of obligations to its customers has occurred, the related fees are fixed or determinable, and collectibility is reasonably assured. Revenue is generated from the following: Transaction-based revenue and Starbucks transaction-based revenue The Company charges its sellers a transaction fee for managed payments solutions that is generally calculated as a percentage of the total transaction amount processed. The Company selectively offers custom pricing for certain sellers. The Company had a processing agreement with Starbucks, for certain Starbucks-owned stores in the United States. During the fourth quarter of 2016, Starbucks completed its previously announced transition to another payments solution provider. The Company recognizes the transaction fees a seller pays to the Company as revenue upon authorization of a transaction by the seller's customer's bank. Revenue is recognized net of refunds, which arise from reversals of transactions initiated by sellers. The Company acts as the merchant of record for its sellers and works directly with payment card networks and banks so that its sellers do not need to manage the complex systems, rules, and requirements of the payments industry. As the merchant of record, Square is liable for settlement of the transactions the Company processes for its sellers. The gross transaction fees collected from sellers are recognized as revenue on a gross basis as the Company is the primary obligor to the seller and is responsible for processing the payment, has latitude in establishing pricing with respect to the sellers and other terms of service, has sole discretion in selecting the third party to perform the settlement, and assumes the credit risk for the transaction processed. Subscription and services-based revenue Subscription and services-based revenue is primarily generated by Instant Deposit, Caviar, Square Capital and various software as a service products. Instant Deposit is a functionality within the Cash App and the Company's managed payment solutions that enables customer to instantly deposit funds into their bank accounts. The Company charges a per transaction fee which we recognize as revenue when customers instantly deposit funds to their bank account. Caviar is a food ordering platform that facilitates food delivery services for restaurants. Caviar revenue consists of fees charged to restaurants, as sellers, and delivery and service fees charged to customers. All fees are recognized upon delivery of the food, net of refunds. Square Capital facilitates a loan that is offered through a partnership with an industrial bank that is generally repaid through withholding a percentage of the collections of the seller's receivables processed by the Company. During the first quarter of 2016, the Company fully transitioned from offering merchant cash advances (MCAs) to loans. The Company facilitates loans to sellers pre-qualified through an analysis of the aggregated data of the seller’s business which includes, but is not limited to, the seller’s historical processing volumes, transaction count, chargebacks, growth, and length of time as a Square customer. The loans are originated by a bank partner, from whom the Company purchases the loans obtaining all rights, title, and interest. The loans have no stated coupon rate but the seller is charged a one-time origination fee by the bank partner based upon their risk rating, which is derived primarily from processing activity. It is the Company’s intent to sell all of its rights, title, and interest of these loans to third-party investors for an upfront fee when the loans are sold. The Company records the net amounts paid to the bank as the cost of the loans purchased and subsequently records a gain on sale of the loans to the third-party investors. The Company is retained by the third-party investors to service the loans and earns a servicing fee for facilitating the repayment of these receivables through its payments solutions. The Company recognizes the gain on sale of the loans to the investors as revenue upon transfer of title to investors. The Company records servicing revenue as servicing is delivered. For the loans which are not sold to third-party investors, the Company recognizes a portion of the expected seller repayments over the cost of the loans as revenue in proportion to the loan principal reduction. Software as a service provides customers with access to various technologies for a fee which is recognized ratably as the service is provided. Hardware revenue Hardware revenue is generated from sales of contactless and chip readers, chip card readers, Square Stand, Square Register and third-party peripherals. Hardware revenue is recorded net of returns and is recognized upon delivery of hardware to the end customer and satisfaction of the other basic revenue recognition criteria. The Company considers delivery to have occurred once title and risk of loss has been transferred to the end customer. The Company records deferred revenue when it receives payments in advance of the delivery of products. Cost of Revenue Transaction-based costs and Starbucks transaction-based costs Transaction-based costs and Starbucks transaction-based costs consist primarily of interchange and assessment fees, processing fees and bank settlement fees paid to third-party payment processors and financial institutions. Contracts with third-party payment processors are typically for a term of two to four years. Subscription and services-based costs Subscription and services-based costs consist primarily of Caviar-related costs, which include payments to third-party couriers for deliveries and the cost of equipment provided to sellers. These costs also include costs associated with Cash App transactions when customers instantly deposit funds to their bank account and for transactions conducted with a Cash Card, credit card or Cash for Business. Cost of revenue for other subscription and services-based costs consists primarily of the amortization related to the development of certain subscription and services-based products. Hardware costs Hardware costs consist of all product costs associated with contactless and chip readers, chip card readers, Square Stand, Square Register and third-party peripherals. Product costs include manufacturing-related overhead and personnel costs, certain royalties, packaging, and fulfillment costs. Advertising Costs Advertising costs are expensed as incurred and included in sales and marketing expense on the consolidated statements of operations. Total advertising costs for the years ended December 31, 2017 , 2016 , and 2015 were $81.9 million , $58.3 million , and $58.3 million , respectively. Share-based Compensation Share-based compensation expense relates to stock options, restricted stock units (RSUs), and purchases under the Company’s 2015 Employee Stock Purchase Plan (ESPP) which is measured based on the grant-date fair value. The fair value of RSUs is determined by the closing price of the Company’s common stock on each grant date.The fair value of stock options and employee stock purchase plan shares granted to employees is estimated on the date of grant using the Black-Scholes-Merton option valuation model. This share-based compensation expense valuation model requires the Company to make assumptions and judgments regarding the variables used in the calculation. These variables include the expected term (weighted average period of time that the options granted are expected to be outstanding), the expected volatility of the Company’s stock, expected risk-free interest rate and expected dividends. The Company uses the simplified calculation of expected term, as the Company does not have sufficient historical data to use any other method to estimate expected term. Expected volatility is based on a weighted average of the historical volatilities of the Company's common stock along with several entities with characteristics similar to those of the Company. The Company will continue to weight its own volatility more heavily as more of its own historical stock price information becomes available. Once its own historical data is equal to that of the expected term of option grants a peer group is no longer considered necessary. The expected risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. Share-based compensation expense is recorded on a straight-line basis over the requisite service period. For the year ended December 31, 2016 and prior, the Company recorded share-based compensation expense net of estimated forfeitures. On January 1, 2017, as a result of the Company's adoption of ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , the Company elected to account for forfeitures as they occur. The fair value of stock options granted to non-employees, including consultants, is initially measured upon the date of grant and remeasured over the vesting period using the same methodology described above. These non-employees provide service to the Company on an ongoing basis, therefore, the performance commitment for each non-employee grant is not considered probable until the award is earned over time. The expected term for non-employee grants is the contractual term and share-based compensation expense is recognized on a straight-line basis over this term. Share-based compensation expense related to non-employees has not been material for any of the periods presented. Income and Other Taxes The Company reports income taxes under the asset and liability approach. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, as well as net operating loss and tax credit carryforwards. Deferred tax amounts are determined by using the enacted tax rates expected to be in effect when the temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance reduces the deferred tax assets to the amount that is more likely than not to be realized. The Company uses financial projections to support its net deferred tax assets, which contain significant assumptions and estimates of future operations. If such assumptions were to differ significantly from actual future results of operations, it may have a material impact on the Company’s ability to realize its deferred tax assets. At the end of each period, the Company assesses the ability to realize the deferred tax assets. If it is more likely than not that the Company would not realize the deferred tax assets, then the Company would establish a valuation allowance for all or a portion of the deferred tax assets. The Company recognizes the effect of uncertain income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that has a greater than 50% likelihood of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company records interest and penalties related to uncertain tax positions in the provision for income tax expense on the consolidated statements of operations. Cash and Cash Equivalents and Restricted Cash The Company considers all highly liquid investments, including money market funds, with an original maturity of three months or less when purchased to be cash equivalents. As of December 31, 2017 and 2016 , restricted cash of $28.8 million and $22.1 million , respectively, is related to pledged cash deposited into savings accounts at the financial institutions that process the Company's sellers' payment transactions and as collateral pursuant to an agreement with the originating bank for the Company's loan product. The Company uses the restricted cash to secure letters of credit with the financial institution to provide collateral for cash flow timing differences in the processing of these payments. The Company has recorded this amount as a current asset on the consolidated balance sheets due to the short-term nature of these cash flow timing differences and that there is no minimum time frame during which the cash must remain restricted. Additionally, this balance includes certain amounts held as collateral pursuant to multi-year lease agreements, discussed in the paragraph below, which we expect to become unrestricted within the next year. As of December 31, 2017 and 2016 , the remaining restricted cash of $9.8 million and $14.6 million , respectively, is primarily related to cash deposited into money market funds that is used as collateral pursuant to multi-year lease agreements entered into in 2012 and 2014 (Note 14 ). The Company has recorded this amount as a non-current asset on the consolidated balance sheets as the terms of the related leases extend beyond one year. Concentration of Credit Risk For the years ended December 31, 2017 and 2016 , the Company had no customer who accounted for greater than 10% of total net revenue. For the year ended December 31, 2015 , the Company had no customer other than Starbucks who accounted for greater than 10% of total net revenue. The Company terminated its relationship with Starbucks during the year ended December 31, 2016. The Company had three third-party payment processors that represented approximately 46% , 42% , and 8% of settlements receivable as of December 31, 2017 . The same three parties represented approximately 52% , 35% , and 10% of settlements receivable as of December 31, 2016 . All other third-party processors were insignificant. Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash, marketable securities, settlements receivables, customer funds, and loans held for sale. The associated risk of concentration for cash and cash equivalents and restricted cash is mitigated by banking with creditworthy institutions. At certain times, amounts on deposit exceed federal deposit insurance limits. The associated risk of concentration for marketable securities is mitigated by holding a diversified portfolio of highly rated investments. Settlements receivable are amounts due from well-established payment processing companies and normally take one or two business days to settle which mitigates the associated risk of concentration. The associated risk of concentration for loans held for sale is partially mitigated by credit evaluations that are performed prior to facilitating the offering of loans and ongoing performance monitoring of the Company’s loan customers. Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. Fair value accounting establishes a three-level hierarchy priority for disclosure of assets and liabilities recorded at fair value. The ordering of priority reflects the degree to which objective prices in external active markets are available to measure fair value. The classification of assets and liabilities within the hierarchy is based on whether the inputs to the valuation methodology used for measurement are observable or unobservable. The Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Company determines fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels: • Level 1 Inputs: Unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date. • Level 2 Inputs: Other than quoted prices included in Level 1 Inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability. • Level 3 Inputs: Unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at measurement date. Loans Held for Sale The Company classifies customer loans as held for sale upon purchase from a bank partner, as there is an available market for such loans and it is the Company’s intent to sell all of its rights, title, and interest in these loans to third-party investors. Loans held for sale are recorded at the lower of amortized cost or fair value determined on an individual loan basis. To determine the fair value the Company utilizes industry-standard valuation modeling, such as discounted cash flow models, taking into account the estimated timing and amounts of periodic repayments. The Company recognizes a charge within transaction, loan and advance losses on the consolidated statement of operations whenever the amortized cost of a loan exceeds its fair value, with such charges being reversed for subsequent increases in fair value, but only to the extent that such reversals do not result in the amortized cost of a loan exceeding its fair value. A loan that is initially designated as held for sale may be reclassified to held for investment if and when the Company's intent for that loan changes. There have been no reclassifications made to date. Settlements Receivable Settlements receivable represents amounts due from third-party payment processors for customer transactions. Settlements receivable are typically received within one or two business days of the transaction date. No valuation allowances have been established, as funds are due from large, well-established financial institutions with no historical collections issue. Customer Funds Customer funds held represent Cash App customers' stored balances that customers would later use to send money or make payments, or customers cash in transit. As of December 31, 2017 and 2016 , the Company held these stored balances as short term bank deposits. Inventory Inventory is comprised of contactless and chip readers, chip card readers, Square Stand, Square Register and third-party peripherals, as well as component parts that are used to manufacture these products. Inventory is stated at the lower of cost (generally on a first-in, first-out basis) or net realizable value. Inventory that is obsolete or in excess of forecasted usage is written down to its net realizable value based on the estimated selling prices in the ordinary course of business. The Company's inventory is held at the Company's warehouses as well as at third party contract manufacturer premises. Deferred Magstripe Reader Costs The Company capitalizes the cost of its magstripe readers, which are included in other current assets on the consolidated balance sheets. The amount capitalized represents the cost of the readers, including packaging and shipping costs, held on-hand by the Company as of each consolidated balance sheet date. Once the readers are shipped to a third-party distributor or an end-customer, they are recorded as marketing expense on the consolidated statements of operations. Property and Equipment Property and equipment are recorded at historical cost less accumulated depreciation, which is computed on a straight-line basis over the asset’s estimated useful life. The estimated useful lives of property and equipment are described below: Property and Equipment Useful Life Capitalized software 18 months Computer and data center equipment Three years Furniture and fixtures Seven years Leasehold improvements Lesser of estimated useful life or remaining lease term When assets are retired or otherwise disposed of, the cost and related accumulated depreciation are removed from their respective accounts, and any gain or loss on such sale or disposal is reflected in operating expenses. Capitalized Software The Company capitalizes certain cost incurred in developing internal-use software when capitalization requirements have been met. Costs prior to meeting the capitalization requirements are expensed as incurred. Capitalized costs are included in property and equipment, net, and amortized on a straight-lined basis over the estimated useful life of the software and included in product development costs or allocated to subscription and service-based costs on the consolidated statements of operations. The Company capitalized $9.8 million , $7.9 million and $4.5 million of internally developed software during the years ended December 31, 2017 , 2016 and 2015 , respectively, and recognized $6.6 million , $7.1 million and $3.2 million of amortization expense during the years ended December 31, 2017 , 2016 and 2015 , respectively. Leases The Company leases office space and equipment under non-cancellable capital and operating leases with various expiration dates. The Company records the total rent expense on a straight-line basis over the lease term. When lease agreements provide allowances for leasehold improvements, the Company capitalizes the leasehold improvement assets and recognizes the related depreciation expense on a straight-line basis over the lesser of the lease term or the estimated useful life of the asset, and reduces rent expense on a straight-line basis over the term of the lease by the amount of the allowances provided. The Company classifies the cash payments for the leasehold improvements within investing activities while reimbursements from the landlords are classified within operating activities. The Company records a liability for the estimated fair value for any asset retirement obligation (ARO) associated with its leases, with an offsetting asset. In the determination of the fair value of AROs, the Company uses various assumptions and judgments, including such factors as the existence of a legal obligation, estimated amounts and timing of settlements, and discount and inflation rates. The liability is subsequently accreted while the asset is depreciated. As of December 31, 2017, the Company had a liability for ARO, gross of accretion, of $3.6 million and an associated asset, net of depreciation, of $2.3 million . Business Combinations The purchase price of an acquisition is allocated to the tangible and intangible assets acquired and liabilities assumed based on their estimated fair values at the acquisition dates. The excess of total consideration over the fair values of the assets acquired and the liabilities assumed is recorded as goodwill. During the measurement period, which may be up to one year from the acquisition date, the Company may record adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments would be recorded on the consolidated statements of operations. Long-Lived Assets, including Goodwill and Acquired Intangibles The Company evaluates the recoverability of property and equipment and finite lived intangible assets for impairment whenever events or circumstances indicate that the carrying amounts of such assets may not be recoverable. Recoverability is measured by comparing the carrying amount of an asset or an asset group to estimate undiscounted future net cash flows expected to be generated. If the carrying amount of the long–lived asset or asset group is not recoverable on an undiscounted cash flow basis, an impairment is recognized to the extent that the carrying amount exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values, and third–part independent appraisals, as considered necessary. For the periods presented, the Company had recorded no impairment charges. Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired in a business combination. The Company performs a goodwill impairment test annually on December 31 and more frequently if events and circumstances indicate that the asset might be impaired. An impairment loss is recognized to the extent that the carrying amount exceeds the reporting unit’s fair value. The Company has the option to first assess qualitative factors to determine whether events or circumstances indicate that it is more likely than not that the fair value of a reporting unit is less than its carrying amount and determine whether further action is needed. If, after assessing the totality of events or circumstances, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. For the periods presented, the Company had recorded no impairment charges. Acquired intangibles consist of acquired technology and customer relationships associated with various acquisitions. Acquired technology is amortized over its estimated useful life on a straight-line basis within cost of revenue. Customer relationships acquired are amortized on a straight-line basis over their estimated useful lives within operating expenses. The Company evaluates the remaining estimated useful life of its intangible assets being amortized on an ongoing basis to determine whether events and circumstances warrant a revision to the remaining period of amortization. Customers Payable Customers payable represents the transaction amounts, less revenue earned by the Company, owed to sellers or Cash App customers. The payable amount comprises amounts owed to customers due to timing differences as we typically settle within one business day, amounts held by the Company in accordance with its risk management policies, and amounts held for customers who have not yet linked a bank account. This balance also includes the Company's liability for customer funds held on the Cash App. Accrued Transaction Losses The Company establishes a reserve for estimated transaction losses due to chargebacks, which represent a potential loss due to disputes between a seller and their customer or due to a fraudulent transaction. The reserve is estimated based on available data as of the reporting date, including expectations of future chargebacks, and historical trends related to loss rates. Additions to the reserve are reflected in current operating results, while charges to the reserve are made when losses are recognized. These amounts are classified within transaction and advance losses on the consolidated statements of operations. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers , and issued subsequent amendments to the initial guidance within ASU 2015-04, ASU 2016-08, ASU 2016-10, ASU 2016-12, and ASU 2016-20. The new guidance will replace all current U.S. GAAP guidance about revenue recognition, including industry specific guidance. The core principal of this new guidance is that revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration for which the Company expects to be entitled in exchange for those goods or services. The new guidance will also change how companies account for certain incremental costs to obtain a customer contract, such as sales commissions, by requiring that such costs be capitalized and charged to expense over the period of expected benefit. This guidance is effective for the Company’s interim and annual financial statements beginning January 1, 2018. The guidance can be adopted either through the full retrospective approach, which requires restatement of all periods presented with a cumulative effect adjustment as of the beginning of the earliest period presen

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS The Company’s financial assets and liabilities that are measured at fair value on a recurring basis are classified as follows (in thousands): December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Cash and cash equivalents: Money market funds $ 387,698 $ — $ — $ 207,168 $ — $ — Commercial paper — 24,695 — — 7,496 — Municipal securities — — — — 1,000 — Short-term securities: U.S. agency securities — 15,083 — — 9,055 — Corporate bonds — 57,798 — — 6,980 — Commercial paper — 17,428 — — 17,298 — Municipal securities — 23,700 — — 8,028 — U.S. government securities 55,567 — — 18,540 — — Long-term securities: U.S. agency securities — 20,169 — — 3,502 — Corporate bonds — 91,413 — — 12,914 — Municipal securities — 26,224 — — 2,492 — U.S. government securities 65,861 — — 8,458 — — Total $ 509,126 $ 276,510 $ — $ 234,166 $ 68,765 $ — The carrying amounts of certain financial instruments, including cash equivalents, settlements receivable, customer funds, accounts payable, customers payable, and settlements payable, approximate their fair values due to their short-term nature. The Company estimates the fair value of its convertible senior notes based on their last actively traded prices (Level 1) or market observable inputs (Level 2). The estimated fair value and carrying value of the convertible senior notes were as follows (in thousands): December 31, 2017 Carrying Value Fair Value (Level 2) Convertible senior notes $ 358,572 $ 719,356 Total $ 358,572 $ 719,356 A summary of loans disclosed at fair value on a recurring basis is as follows (in thousands): December 31, 2017 December 31, 2016 Carrying Value Fair Value (Level 3) Carrying Value Fair Value (Level 3) Loans held for sale $ 73,420 $ 76,070 $ 42,144 $ 42,633 Total $ 73,420 $ 76,070 $ 42,144 $ 42,633 For the year ended December 31, 2017 , the Company recorded a charge for the excess of amortized cost over fair value of the loans of $8.0 million . No charges were recorded for the years ended December 31, 2016 and 2015 . If applicable, the Company will recognize transfers into and out of levels within the fair value hierarchy at the end of the reporting period in which the actual event or change in circumstance occurs. During the years ended December 31, 2017 , 2016 and 2015 , the Company did not have any transfers in or out of Level 1, Level 2, or Level 3 assets or liabilities.

INVESTMENTS

INVESTMENTS	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
INVESTMENTS	INVESTMENTS The Company determines the appropriate classification of its investments in marketable securities at the time of purchase and reevaluates such designation at each balance sheet date. The Company has classified and accounted for its marketable securities as available-for-sale. The Company's short-term and long-term investments as of December 31, 2017 are as follows (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term securities: U.S. agency securities $ 15,122 $ — $ (39 ) $ 15,083 Corporate bonds 57,855 22 (79 ) 57,798 Commercial paper 17,428 — — 17,428 Municipal securities 23,743 8 (51 ) 23,700 U.S. government securities 55,729 1 (163 ) 55,567 Total $ 169,877 $ 31 $ (332 ) $ 169,576 Long-term securities: U.S. agency securities $ 20,288 $ 2 $ (121 ) $ 20,169 Corporate bonds 91,959 25 (571 ) 91,413 Municipal securities 26,371 13 (160 ) 26,224 U.S. government securities 66,362 19 (520 ) 65,861 Total $ 204,980 $ 59 $ (1,372 ) $ 203,667 The Company's short-term and long-term investments as of December 31, 2016 are as follows (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term securities: U.S. agency securities $ 9,048 $ 7 $ — $ 9,055 Corporate bonds 17,318 — (20 ) 17,298 Commercial paper 6,980 — — 6,980 Municipal securities 8,037 — (9 ) 8,028 U.S. government securities 18,537 3 — 18,540 Total $ 59,920 $ 10 $ (29 ) $ 59,901 Long-term securities: U.S. agency securities $ 3,502 $ — $ — $ 3,502 Corporate bonds 12,939 — (25 ) 12,914 Municipal securities 2,505 — (13 ) 2,492 U.S. government securities 8,478 — (20 ) 8,458 Total $ 27,424 $ — $ (58 ) $ 27,366 For the years ended December 31, 2017 , 2016 and 2015 , gains or losses realized on the sale of investments were not material. Investments are reviewed periodically to identify possible other-than-temporary impairments. As the Company has the ability and intent to hold these investments with unrealized losses until a recovery of fair value, or for a reasonable period of time sufficient for the recovery of fair value, which may be maturity, the Company does not consider these investments to be other-than-temporarily impaired for any of the periods presented. The contractual maturities of the Company's short-term and long-term investments as of December 31, 2017 are as follows (in thousands): Amortized Cost Fair Value Due in one year or less $ 169,877 $ 169,576 Due in one to five years 204,980 203,667 Total $ 374,857 $ 373,243

PROPERTY AND EQUIPMENT, NET

PROPERTY AND EQUIPMENT, NET	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT, NET	PROPERTY AND EQUIPMENT, NET The following is a summary of property and equipment, less accumulated depreciation and amortization (in thousands): December 31, December 31, Computer equipment $ 66,186 $ 52,915 Office furniture and equipment 14,490 10,737 Leasehold improvements 77,073 73,366 Capitalized software 35,063 24,642 Total 192,812 161,660 Less: Accumulated depreciation and amortization (101,316 ) (73,332 ) Property and equipment, net $ 91,496 $ 88,328 Depreciation and amortization expense on property and equipment was $29.7 million , $28.7 million , and $20.1 million , for the years ended December 31, 2017 , 2016 , and 2015 , respectively.

GOODWILL

GOODWILL	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL	GOODWILL Goodwill is recorded when the consideration paid for an acquisition of a business exceeds the fair value of identifiable net tangible and intangible assets acquired. As of December 31, 2017 and December 31, 2016 , goodwill was $58.3 million and $57.2 million , respectively. The Company performed its annual goodwill impairment test as of December 31, 2017 . The Company determined that the consolidated business is represented by a single reporting unit and through qualitative analysis concluded that it was more likely than not that the fair value of the reporting unit was greater than its carrying amount. As a result, the two-step goodwill impairment test was not required, and no impairments of goodwill were recognized during the year ended December 31, 2017 .

ACQUIRED INTANGIBLE ASSETS

ACQUIRED INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
ACQUIRED INTANGIBLE ASSETS	ACQUIRED INTANGIBLE ASSETS During the years ended December 31, 2017 and 2016 , the Company did not make any material acquisitions. The following table presents the detail of acquired intangible assets as of the periods presented (in thousands): Balance at December 31, 2017 Cost Accumulated Amortization Net Patents $ 1,285 $ (559 ) $ 726 Technology Assets 29,158 (21,329 ) 7,829 Customer Assets 10,319 (4,540 ) 5,779 Total $ 40,762 $ (26,428 ) $ 14,334 Balance at December 31, 2016 Cost Accumulated Amortization Net Patents $ 1,285 $ (454 ) $ 831 Technology Assets 29,075 (14,702 ) 14,373 Customer Assets 7,745 (3,657 ) 4,088 Total $ 38,105 $ (18,813 ) $ 19,292 The weighted average amortization periods for acquired patents, technology, and customer intangible assets are approximately 13 years , 4 years , and 9 years , respectively. Amortization expense associated with acquired intangible assets was $7.6 million , $9.0 million , and $7.5 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The total estimated annual future amortization expense of these intangible assets as of December 31, 2017 , is as follows (in thousands): 2018 $ 6,226 2019 3,442 2020 1,479 2021 846 2022 611 Thereafter 1,730 Total $ 14,334

OTHER CONSOLIDATED BALANCE SHEE

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (CURRENT)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (CURRENT)	OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (CURRENT) Other Current Assets The following table presents the detail of other current assets (in thousands): December 31, December 31, Inventory, net $ 16,777 $ 13,724 Processing costs receivable 21,083 10,049 Prepaid expenses 14,473 7,365 Accounts receivable, net 8,606 6,191 Deferred hardware costs 7,931 4,546 Deferred magstripe reader costs 2,469 3,911 Merchant cash advance receivable, net 125 4,212 Other 14,990 10,545 Total $ 86,454 $ 60,543 Accrued Expenses The following table presents the detail of accrued expenses (in thousands): December 31, December 31, Accrued payroll $ 9,103 $ 5,799 Accrued professional fees 5,638 5,788 Accrued advertising and other marketing 6,723 5,008 Processing costs payable 10,145 10,871 Accrued non income tax liabilities 6,155 3,562 Accrued hardware costs 2,496 3,148 Other accrued liabilities $ 12,020 $ 5,367 Total $ 52,280 $ 39,543 Other Current Liabilities The following table presents the detail of other current liabilities (in thousands): December 31, December 31, Square Capital payable (i) $ 7,671 $ 4,907 Square Payroll payable (ii) 2,850 4,769 Deferred revenue 5,893 5,407 Current portion of deferred rent 3,311 2,862 Accrued redemptions 1,036 1,628 Other 7,606 2,899 Total $ 28,367 $ 22,472 (i) Square Capital payable represents unpaid amounts arising from the purchase of loans or loan repayments collected on behalf of third parties. (ii) Square Payroll payable represents amounts received from Square Payroll product customers that will be utilized to settle the customers employee payroll and related obligations. OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (NON-CURRENT) Other Non-Current Assets The following table presents the detail of other non-current assets (in thousands): December 31, December 31, Investment in privately held entity (i) $ 25,000 $ — Deposits 2,738 1,775 Debt issuance costs 788 1,063 Deferred tax assets 519 306 Other 2,305 50 Total $ 31,350 $ 3,194 (i) In August, 2017, the Company invested $25.0 million in Eventbrite, a leader in event technology providing a platform that facilitates ticket sales, as well as promotion and management of events. In conjunction with the investment, the Company entered into an agreement with Eventbrite specifying terms under which the Company would provide payment processing services to Eventbrite and its customers for a five year term in the countries in which the Company operates. This agreement is subject to automatic one year renewals thereafter unless terminated by either party. Eventbrite and the Company have a common member on their respective boards of directors. The Company has not estimated the fair value of the investment as it has determined that it is not practicable to determine such fair value, and there are no identified events or changes in circumstances that may have a significant adverse effect on the fair value. Other Non-Current Liabilities The following table presents the detail of other non-current liabilities (in thousands): December 31, December 31, Statutory liabilities (ii) $ 40,768 $ 29,497 Deferred rent 20,349 23,119 Deferred tax liabilities 644 476 Other 7,777 4,653 Total $ 69,538 $ 57,745 (ii) Statutory liabilities represent loss contingencies that may arise from the Company's interpretation and application of certain guidelines and rules issued by various federal, state, local, and foreign regulatory authorities.

OTHER CONSOLIDATED BALANCE SH15

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (NON-CURRENT)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (NON-CURRENT)	OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (CURRENT) Other Current Assets The following table presents the detail of other current assets (in thousands): December 31, December 31, Inventory, net $ 16,777 $ 13,724 Processing costs receivable 21,083 10,049 Prepaid expenses 14,473 7,365 Accounts receivable, net 8,606 6,191 Deferred hardware costs 7,931 4,546 Deferred magstripe reader costs 2,469 3,911 Merchant cash advance receivable, net 125 4,212 Other 14,990 10,545 Total $ 86,454 $ 60,543 Accrued Expenses The following table presents the detail of accrued expenses (in thousands): December 31, December 31, Accrued payroll $ 9,103 $ 5,799 Accrued professional fees 5,638 5,788 Accrued advertising and other marketing 6,723 5,008 Processing costs payable 10,145 10,871 Accrued non income tax liabilities 6,155 3,562 Accrued hardware costs 2,496 3,148 Other accrued liabilities $ 12,020 $ 5,367 Total $ 52,280 $ 39,543 Other Current Liabilities The following table presents the detail of other current liabilities (in thousands): December 31, December 31, Square Capital payable (i) $ 7,671 $ 4,907 Square Payroll payable (ii) 2,850 4,769 Deferred revenue 5,893 5,407 Current portion of deferred rent 3,311 2,862 Accrued redemptions 1,036 1,628 Other 7,606 2,899 Total $ 28,367 $ 22,472 (i) Square Capital payable represents unpaid amounts arising from the purchase of loans or loan repayments collected on behalf of third parties. (ii) Square Payroll payable represents amounts received from Square Payroll product customers that will be utilized to settle the customers employee payroll and related obligations. OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (NON-CURRENT) Other Non-Current Assets The following table presents the detail of other non-current assets (in thousands): December 31, December 31, Investment in privately held entity (i) $ 25,000 $ — Deposits 2,738 1,775 Debt issuance costs 788 1,063 Deferred tax assets 519 306 Other 2,305 50 Total $ 31,350 $ 3,194 (i) In August, 2017, the Company invested $25.0 million in Eventbrite, a leader in event technology providing a platform that facilitates ticket sales, as well as promotion and management of events. In conjunction with the investment, the Company entered into an agreement with Eventbrite specifying terms under which the Company would provide payment processing services to Eventbrite and its customers for a five year term in the countries in which the Company operates. This agreement is subject to automatic one year renewals thereafter unless terminated by either party. Eventbrite and the Company have a common member on their respective boards of directors. The Company has not estimated the fair value of the investment as it has determined that it is not practicable to determine such fair value, and there are no identified events or changes in circumstances that may have a significant adverse effect on the fair value. Other Non-Current Liabilities The following table presents the detail of other non-current liabilities (in thousands): December 31, December 31, Statutory liabilities (ii) $ 40,768 $ 29,497 Deferred rent 20,349 23,119 Deferred tax liabilities 644 476 Other 7,777 4,653 Total $ 69,538 $ 57,745 (ii) Statutory liabilities represent loss contingencies that may arise from the Company's interpretation and application of certain guidelines and rules issued by various federal, state, local, and foreign regulatory authorities.

INDEBTEDNESS

INDEBTEDNESS	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
INDEBTEDNESS	INDEBTEDNESS Revolving Credit Facility In November 2015 , the Company entered into a revolving credit agreement with certain lenders, which extinguished the prior revolving credit agreement and provided for a $375.0 million revolving secured credit facility maturing in November 2020 . This revolving credit agreement is secured by certain tangible and intangible assets. Loans under the credit facility bear interest, at the Company’s option of (i) a base rate based on the highest of the prime rate, the federal funds rate plus 0.50% and an adjusted LIBOR rate for a one-month interest period in each case plus a margin ranging from 0.00% to 1.00% , or (ii) an adjusted LIBOR rate plus a margin ranging from 1.00% to 2.00% . This margin is determined based on the Company’s total leverage ratio for the preceding four fiscal quarters. The Company is obligated to pay other customary fees for a credit facility of this size and type including an annual administrative agent fee of $0.1 million and an unused commitment fee of 0.15% . To date no funds have been drawn under the credit facility, with $375.0 million remaining available. The Company paid $0.6 million in unused commitment fees for both the years ended December 31, 2017 and 2016 . As of December 31, 2017 , the Company was in compliance with all financial covenants associated with this credit facility. Convertible Senior Notes On March 6, 2017, the Company issued an aggregate principal amount of $400.0 million of convertible senior notes (Notes) and an additional 10% or $40.0 million pursuant to the exercise in full of the option to the initial purchasers to cover over-allotments. The Notes mature on March 1, 2022, unless earlier converted or repurchased, and bear interest at a rate of 0.375% payable semi-annually on March 1 and September 1 of each year. The Notes are convertible at an initial conversion rate of 43.5749 shares of the Company's Class A common stock per $1,000 principal amount of Notes, which is equivalent to an initial conversion price of approximately $22.95 per share of Class A common stock. Holders may convert their Notes at any time prior to the close of business on the business day immediately preceding December 1, 2021 only under the following circumstances: (1) during any calendar quarter (and only during such calendar quarter), if the last reported sale price of the Company’s Class A common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the measurement period) in which the trading price (as defined in the indenture governing the Notes) per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s Class A common stock and the conversion rate on each such trading day; or (3) upon the occurrence of specified corporate events, including certain distributions, the occurrence of a fundamental change (as defined in the indenture governing the Notes) or a transaction resulting in the Company’s Class A common stock converting into other securities or property or assets. On or after December 1, 2021, up until the close of business on the second scheduled trading day immediately preceding the maturity date, a holder may convert all or any portion of its Notes regardless of the foregoing circumstances. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of its Class A common stock, or a combination of cash and shares of its Class A common stock, at the Company’s election. It is the Company’s current intent and policy to settle conversions through combination settlement with a specified dollar amount of $1,000 per $1,000 principal amount of Notes. The circumstances required to allow the holders to convert their Notes were met as of January 1, 2018. As of February 27, 2018, no holders have converted their Notes. In accounting for the issuance of the Notes, the Company separated the Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was $86.2 million and was determined by deducting the fair value of the liability component from the par value of the Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount ("debt discount") is amortized to interest expense over the term of the Notes at an effective interest rate of 5.34% over the contractual terms of the Notes. Debt issuance costs related to the Notes comprised of discounts and commissions payable to the initial purchasers of $11.0 million and third party offering costs of $0.8 million . The Company allocated the total amount incurred to the liability and equity components of the Notes based on their relative values. Issuance costs attributable to the liability component were $9.4 million and will be amortized to interest expense using the effective interest method over the contractual term. Issuance costs attributable to the equity component were netted with the equity component in stockholders’ equity. The Notes consisted of the following (in thousands): December 31, 2017 Principal $ 440,000 Less: unamortized debt discount (73,384 ) Less: unamortized debt issuance costs (8,044 ) Net carrying amount $ 358,572 The net carrying amount of the equity component of the Notes was as follows (in thousands): December 31, 2017 Debt discount related to value of conversion option $ 86,203 Less: allocated debt issuance costs (2,302 ) Equity component, net $ 83,901 The Company recognized interest expense on the Notes as follows (in thousands, except for percentages): Year Ended December 31, 2017 Contractual interest expense based on 0.375% per annum 1,351 Amortization of debt discount and issuance costs 14,223 Total 15,574 Effective interest rate of the liability component 5.34 % Convertible Note Hedge and Warrant Transactions In connection with the offering of the Notes, the Company entered into convertible note hedge transactions with certain financial institutions (Counterparties) whereby the Company has the option to purchase a total of approximately 19.2 million shares of its Class A common stock at a price of approximately $22.95 per share. The total cost of the convertible note hedge transactions was approximately $92.1 million . In addition, the Company sold warrants to the Counterparties whereby the Counterparties have the option to purchase a total of approximately 19.2 million shares of the Company’s Class A common stock at a price of approximately $31.18 per share. The Company received approximately $57.2 million in cash proceeds from the sale of these warrants. Taken together, the purchase of the convertible note hedges and sale of the warrants are intended to reduce dilution from the conversion of the Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of the converted Notes, as the case may be, and to effectively increase the overall conversion price from approximately $22.95 per share to approximately $31.18 per share. As these instruments are considered indexed to the Company's own stock and are considered equity classified, the convertible note hedges and warrants are recorded in stockholders’ equity, are not accounted for as derivatives and are not remeasured each reporting period. The net costs incurred in connection with the convertible note hedge and warrant transactions were recorded as a reduction to additional paid-in capital on the consolidated balance sheets.

ACCRUED TRANSACTION LOSSES

ACCRUED TRANSACTION LOSSES	12 Months Ended
	Dec. 31, 2017
Product Warranties Disclosures [Abstract]
ACCRUED TRANSACTION LOSSES	ACCRUED TRANSACTION LOSSES The Company is exposed to transaction losses due to chargebacks as a result of fraud or uncollectibility. The following table summarizes the activities of the Company’s reserve for transaction losses (in thousands): Year Ended December 31, 2017 2016 2015 Accrued transaction losses, beginning of the year $ 20,064 $ 17,176 $ 8,452 Provision for transaction losses 52,977 50,819 43,379 Charge-offs to accrued transaction losses (46,148 ) (47,931 ) (34,655 ) Accrued transaction losses, end of the year $ 26,893 $ 20,064 $ 17,176

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The domestic and foreign components of loss before income taxes are as follows (in thousands): Year Ended December 31, 2017 2016 2015 Domestic $ (10,900 ) $ (145,499 ) $ (157,229 ) Foreign (51,764 ) (24,174 ) (18,842 ) Loss before income taxes $ (62,664 ) $ (169,673 ) $ (176,071 ) The components of the provision for income taxes are as follows (in thousands): Year Ended December 31, 2017 2016 2015 Current: Federal $ (1,192 ) $ 63 $ 1,662 State 739 527 836 Foreign 1,987 1,269 1,222 Total current provision for income taxes 1,534 1,859 3,720 Deferred: Federal (1,169 ) 173 67 State 57 18 11 Foreign (273 ) (133 ) (52 ) Total deferred provision for income taxes (1,385 ) 58 26 Total provision for income taxes $ 149 $ 1,917 $ 3,746 The following is a reconciliation of the statutory federal income tax rate to the Company's effective tax rate: Balance at December 31, 2017 2016 2015 Tax at federal statutory rate 34.0 % 34.0 % 34.0 % State taxes, net of federal benefit (0.4 ) (0.1 ) (0.2 ) Foreign rate differential (14.9 ) (2.4 ) (1.8 ) Nondeductible expenses (1.0 ) (0.9 ) (1.1 ) Credits 41.5 8.5 8.2 Other items (1.2 ) 0.2 0.1 Change in valuation allowance (119.5 ) (37.4 ) (38.6 ) Impact of U.S. tax reform (209.1 ) — — Share-based compensation (i) 243.5 (2.4 ) (2.2 ) Change in uncertain tax positions (2.4 ) (0.6 ) (0.5 ) Termination of warrant 29.3 — — Total (0.2 )% (1.1 )% (2.1 )% (i) Starting in 2017, excess tax benefits from share-based award activity are reflected in the provision for income taxes. The tax effects of temporary differences and related deferred tax assets and liabilities are as follows (in thousands): Balance at December 31, 2017 2016 2015 Deferred tax assets: Capitalized costs $ 35,608 $ 61,897 $ 67,051 Accrued expenses 23,553 29,421 27,964 Net operating loss carryforwards 244,197 65,507 36,633 Tax credit carryforwards 60,567 38,927 25,349 Property, equipment and intangible assets 7,390 5,721 — Share-based compensation 35,728 52,091 36,689 Other 2,519 1,640 1,469 Total deferred tax assets 409,562 255,204 195,155 Valuation allowance (409,043 ) (254,898 ) (195,103 ) Total deferred tax assets, net of valuation allowance 519 306 52 Deferred tax liabilities: Property, equipment and intangible assets (644 ) (476 ) (163 ) Total deferred tax liabilities (644 ) (476 ) (163 ) Net deferred tax liabilities $ (125 ) $ (170 ) $ (111 ) On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act ("2017 Tax Act"). The 2017 Tax Act makes broad and complex changes to the U.S. tax code, including, but not limited to, (1) reducing the U.S. Federal corporate tax rate from 35% to 21%; (2) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (3) in part eliminating U.S. Federal income taxes on dividends from foreign subsidiaries; (4) requiring a current inclusion in U.S. Federal taxable income of certain unrepatriated earnings of controlled foreign corporations; (5) eliminating the corporate alternative minimum tax ("AMT") and changing how existing AMT credits can be realized; (6) creating the base erosion anti-abuse tax ("BEAT"), a new minimum tax; (7) creating a new limitation on deductible interest expense; and (8) changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after December 31, 2017. In connection with the Company's analysis of the impact of the 2017 Tax Act, it recorded a net tax benefit of $ 1.3 million in the period ended December 31, 2017 . The net benefit consists of the release of the valuation allowance on the Company's AMT credit carryforward, which will be refunded in tax years 2018-2021. In addition, the 2017 Tax Act reduces the corporate tax rate to 21%, effective January 1, 2018. Consequently, the Company has recorded a decrease of $ 63.6 million , with an offset to the valuation allowance, to its U.S. Federal and state deferred tax assets. The Company has also completed its analysis of the deemed repatriation transition tax and has concluded that it will not owe any transition tax. Additionally, on December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 ("SAB 118") to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the 2017 Tax Act. The Company has recognized the tax impacts related to refundable AMT credits and revaluation of deferred tax assets, offset by the valuation allowance, and included these amounts in its consolidated financial statements for the year ended December 31, 2017. The ultimate impact may differ from the amounts recorded due to, among other things, additional analysis, changes in interpretations and assumptions as applicable, and additional regulatory guidance that may be issued. Any difference is not expected to be material. The accounting is expected to be complete when the 2017 U.S. corporate income tax return is filed in 2018. Realization of deferred tax assets is dependent upon the generation of future taxable income, the timing and amount of which are uncertain. Due to the history of losses generated in the U.S. and certain foreign jurisdictions, the Company believes that it is more likely than not that its deferred tax assets in these jurisdictions will not be realized as of December 31, 2017 . Accordingly, the Company retained a full valuation allowance on its deferred tax assets in these jurisdictions. The amount of deferred tax assets considered realizable in future periods may change as management continues to reassess the underlying factors it uses in estimating future taxable income. The valuation allowance increased by approximately $154.1 million , $59.8 million , and $69.7 million during the years ended December 31, 2017 , 2016 , and 2015 , respectively. As of December 31, 2017 , the Company had $774.2 million of Federal, $594.2 million of state, and $131.7 million of foreign net operating loss carryforwards, which will begin to expire in 2035 for Federal and 2021 for state tax purposes. The foreign net operating loss carryforwards do not expire. As of December 31, 2017 , the Company had $42.6 million of Federal, $31.1 million of state, and $1.6 million of Canadian research credit carryforwards. The Federal credit carryforward will begin to expire in 2029, the state credit carryforward has no expiration date, and the Canadian credit carryforward will begin to expire in 2035. The Company also has a Federal AMT credit carryforward of $1.3 million that will be refunded over the 2018-2021 tax years under the 2017 Tax Act. The Company has California Enterprise Zone credit carryforwards of $2.8 million , which will begin to expire in 2023. Utilization of the net operating loss carryforwards and credits may be subject to annual limitations due to the ownership change limitations provided by the Internal Revenue Code of 1986, as amended, and similar state provisions. The annual limitations may result in the expiration of net operating losses and credits before they are able to be utilized. The Company does not expect any previous ownership changes, as defined under Section 382 and 383 of the Internal Revenue Code, to result in a limitation that will reduce the total amount of net operating loss carryforwards and credits that can be utilized. As of December 31, 2017 , the unrecognized tax benefit was $70.8 million , of which $4.5 million would impact the annual effective tax rate if recognized and the remainder of which would result in a corresponding adjustment to the valuation allowance. A reconciliation of the beginning and ending amount of unrecognized tax benefit is presented below (in thousands): Year Ended December 31, 2017 2016 2015 Balance at the beginning of the year $ 92,134 $ 90,372 $ 78,031 Gross increases and decreases related to prior period tax positions — 5,190 — Gross increases and decreases related to current period tax positions 4,193 (3,428 ) 12,341 Reductions related to lapse of statute of limitations (91 ) — — Gross increases and decreases related to U.S. tax reform (25,437 ) — — Balance at the end of the year $ 70,799 $ 92,134 $ 90,372 The Company recognizes interest and penalties related to income tax matters as a component of income tax expense. As of December 31, 2017 , there were no significant accrued interest and penalties related to uncertain tax positions. It is reasonably possible that over the next 12-month period the Company may experience a decrease in its unrecognized tax benefits as a result of tax examinations or lapses of statute of limitations. The estimated decrease in unrecognized tax benefits may range up to $ 13 million . The Company is subject to taxation in the United States and various state and foreign jurisdictions. The Company is currently under examination in California for tax years 2013 and 2014 and other jurisdictions for tax years 2013-2016. The Company’s various tax years starting with 2009 to 2016 remain open in various taxing jurisdictions. As of December 31, 2017 , the Company has not provided deferred U.S. income taxes or foreign withholding taxes on temporary differences resulting from earnings for certain non-U.S. subsidiaries, which are permanently reinvested outside the U.S. Cumulative undistributed earnings for these non-U.S. subsidiaries as of December 31, 2017 are $4.1 million . Furthermore, the Company has accumulated deficits such that no U.S. tax is expected to be due as a result of U.S. tax reform related to IRC Section 965.

STOCKHOLDER'S EQUITY

STOCKHOLDER'S EQUITY	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
STOCKHOLDER'S EQUITY	STOCKHOLDERS' EQUITY Initial Public Offering In November 2015 , the Company completed its IPO in which it issued and sold 29,700,000 shares of Class A common stock at a public offering price of $9.00 per share. The total net proceeds received from the IPO were $245.7 million after deducting underwriting discounts and commissions of $14.7 million and other offering expenses of approximately $6.9 million . Convertible Preferred Stock As of December 31, 2017 , the Company is authorized to issue 100,000,000 shares of preferred stock, with a $0.0000001 par value. No shares of preferred stock are outstanding as of December 31, 2017 . Deemed Dividend on Series E Preferred Stock On November 24, 2015, upon the closing of the IPO, certain holders of Series E preferred stock were issued an incremental 10,299,696 shares of Class B common stock pursuant to the Company's Restated Certificate of Incorporation dated as of September 8, 2014, as amended (the "2014 Certificate"). The 2014 Certificate allowed for an adjustment to the Series E original conversion price based on a prescribed formula upon the Company's IPO. The conversion of the Series E preferred stock resulted in a beneficial conversion feature, analogous to a deemed dividend. The beneficial conversion feature was calculated as the difference between fair value of the Company's common stock ultimately issued, based on the commitment date fair value of the Company's common stock, and the initial proceeds received for the Series E preferred stock. As a result, the Company recorded a one-time $32.2 million deemed stock dividend that resulted in an increase to net loss to arrive at net loss attributable to common stockholders. Common Stock The Company has authorized the issuance of Class A common stock and Class B common stock. Holders of the Company's Class A common stock and Class B common stock are entitled to dividends when, as and if, declared by the Company's board of directors, subject to the rights of the holders of all classes of stock outstanding having priority rights to dividends. As of December 31, 2017 , the Company did not declare any dividends. Holders of shares of Class A common stock are entitled to one vote per share, while holders of shares of Class B common stock are entitled to ten votes per share. Shares of the Company's Class B common stock are convertible into an equivalent number of shares of its Class A common stock and generally convert into shares of its Class A common stock upon transfer. Class A common stock and Class B common stock are referred to as common stock throughout these Notes to the Consolidated Financial Statements, unless otherwise noted. The holders of Class A common stock and Class B common stock have no preemptive or other subscription rights and there are no redemption or sinking fund provisions with respect to such shares. As of December 31, 2017 , the Company was authorized to issue 1,000,000,000 shares of Class A common stock and 500,000,000 shares of Class B common stock, each with a par value of $0.0000001 per share. As of December 31, 2017 , the Company had outstanding 280,400,813 shares of Class A common stock and 114,793,262 shares of Class B common stock. Warrants On August 7, 2012, the Company entered into a processing agreement with Starbucks and issued warrants to purchase 15,761,575 shares of common stock that would become exercisable if certain performance conditions, specified in the agreement as subsequently amended between 2012 and 2015, were achieved. In 2015, warrants to purchase 6,304,620 shares of common stock were canceled. On February 24, 2017, the Company and Starbucks entered into a Warrant Cancellation and Payment Agreement pursuant to which the Company paid Starbucks cash consideration of approximately $54.8 million in return for the termination of the Warrant to Purchase Stock dated August 7, 2012, as amended, that provided Starbucks with the right to purchase an aggregate of approximately 9.5 million shares of the Company’s common stock. In conjunction with the Notes offering, the Company sold warrants whereby the Counterparties have the option to purchase a total of approximately 19.2 million shares of the Company’s Class A common stock at a price of $31.18 per share. The Company received $57.2 million in cash proceeds from the sale of these warrants. See Note 9 , Indebtedness , for more details on this transaction. As of December 31, 2017 , the Company had outstanding warrants to purchase an aggregate of 19,172,956 shares of its capital stock, with a weighted average exercise price of approximately $31.18 per share. Stock Plans The Company maintains two share-based employee compensation plans: the 2009 Stock Option Plan (2009 Plan) and the 2015 Equity Incentive Plan (2015 Plan). The 2015 Plan serves as the successor to its 2009 Plan. The 2015 Plan became effective as of November 17, 2015. Outstanding awards under the 2009 Plan continue to be subject to the terms and conditions of the 2009 Plan. Under the 2015 Plan, shares of common stock are reserved for the issuance of incentive stock options (ISOs), non-statutory stock options (NSOs), restricted stock awards, RSUs, performance shares and stock bonuses to qualified employees, directors and consultants. The shares may be granted at a price per share not less than the fair market value at the date of grant. Initially, 30,000,000 shares were reserved under the 2015 Plan and any shares subject to options or other similar awards granted under the 2009 Plan that expire, are forfeited, are repurchased by the Company or otherwise terminate unexercised will become available under the 2015 Plan. The number of shares available for issuance under the 2015 Plan will be increased on the first day of each fiscal year, in an amount equal to the least of (i) 40,000,000 shares, (ii) 5% of the outstanding shares of the Company's common stock on the last day of the immediately preceding fiscal year, or (iii) such number of shares determined by the administrator. As of December 31, 2017 , the total number of options and RSUs outstanding under the 2015 Plan was 25,971,958 shares, and 45,785,515 shares were available for future issuance. Under the 2009 Plan, shares of common stock are reserved for the issuance of ISOs or NSOs to eligible participants. The options may be granted at a price per share not less than the fair market value at the date of grant. Options granted generally vest over a four -year term from the date of grant, at a rate of 25% after one year, then monthly on a straight-line basis thereafter. Generally, options granted are exercisable for up to 10 years from the date of grant. The Plan allows for early exercise of employee stock options whereby the option holder is allowed to exercise prior to vesting. Any unvested shares are subject to repurchase by the Company at their original exercise prices. As of December 31, 2017 , the total number of options and RSUs outstanding under the 2009 Plan was 42,615,658 shares. No additional shares will be issued under 2009 Plan, effective November 17, 2015. In January 2015, the Company’s Chief Executive Officer contributed 5,068,238 shares of common stock back to the Company for no consideration. The purpose of the contribution was to retire such shares in order to offset stock ownership dilution to existing investors in connection with future issuances under the 2009 Plan. A summary of stock option activity for the year ended December 31, 2017 is as follows (in thousands, except share and per share data): Number of stock options outstanding Weighted Weighted Aggregate Balance at December 31, 2016 73,261,562 $ 7.70 7.28 $ 443,711 Granted 1,216,959 17.2 Exercised (24,510,745 ) 5.91 Forfeited and canceled (2,697,685 ) 11.36 Balance at December 31, 2017 47,270,091 $ 8.67 6.52 $ 1,229,103 Options vested and expected to vest at December 31, 2017 47,270,091 $ 8.67 6.52 $ 1,229,103 Options exercisable at December 31, 2017 44,252,865 $ 8.37 6.38 $ 1,163,690 Aggregate intrinsic value represents the difference between the Company’s estimated fair value of its common stock and the exercise price of outstanding, “in-the-money” options. Aggregate intrinsic value for stock options exercised through December 31, 2017 , 2016 , and 2015 was $464.1 million , $202.6 million , and $49.8 million , respectively. The total weighted average grant-date fair value of options granted was $5.97 , $5.80 and $5.87 per share for the years ended December 31, 2017 , 2016 and 2015 , respectively. Restricted Stock Activity The Company issues restricted stock units (RSUs) under the 2015 Plan, which typically vest over a term of four years. Activity related to RSUs during the year ended December 31, 2017 is set forth below: Number of Weighted Unvested at December 31, 2016 15,443,391 $ 12.09 Granted 14,256,257 21.21 Vested (5,964,153 ) 12.83 Forfeited (2,417,970 ) 13.29 Unvested at December 31, 2017 21,317,525 $ 17.84 Employee Stock Purchase Plan On November 17, 2015 , the Company’s 2015 Employee Stock Purchase Plan (ESPP) became effective. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP provides for 12 -month offering periods. The offering periods are scheduled to start on the first trading day on or after May 15 and November 15 of each year, except for the first offering period, which commenced on November 19, 2015 and ended on November 15, 2016. Each offering period includes two purchase periods, which begin on the first trading day on or after November 15 and May 15, and ending on the last trading day on or before May 15 and November 15, respectively. Employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or the last trading day of the purchase period. The number of shares available for sale under the ESPP will be increased annually on the first day of each fiscal year, equal to the least of (i) 8,400,000 shares, (ii) 1% of the outstanding shares of the Company’s common stock as of the last day of the immediately preceding fiscal year, or (iii) such other amount as determined by the administrator. As of December 31, 2017 , 3,522,945 shares had been purchased under the ESPP and 7,672,022 shares were available for future issuance under the ESPP. The Company recorded $6.0 million and $5.1 million of share-based compensation expense related to the ESPP during the year ended December 31, 2017 and 2016 , respectively. Share-Based Compensation The fair value of stock options was estimated using the following weighted-average assumptions: Year Ended December 31, 2017 2016 2015 Dividend yield — % — % — % Risk-free interest rate 1.88 % 1.54 % 1.73 % Expected volatility 32.22 % 42.74 % 47.68 % Expected term (years) 6.02 6.08 6.02 Effective August 31, 2015 , the Company modified all of its nonstatutory stock option grants to extend the exercise term for terminated employees who have completed two years of service. During the year ended December 31, 2017 , 2016 , and 2015 , share-based compensation expense includes $1.9 million , $2.6 million , and $3.3 million , respectively, related to the vested portion of the impacted options as a result of the modification. The Company will incur an additional $1.9 million of share-based compensation expense over the remaining vesting periods of the impacted options. The following table summarizes the effects of share-based compensation on the Company's consolidated statements of operations (in thousands): Year Ended December 31, 2017 2016 2015 Cost of revenue $ 77 $ — $ — Product development 98,310 91,404 54,738 Sales and marketing 17,568 14,122 7,360 General and administrative 39,881 33,260 20,194 Total $ 155,836 $ 138,786 $ 82,292 The Company capitalized $3.7 million and $2.8 million of share-based compensation expense related to capitalized software during the year ended December 31, 2017 and 2016 . There was no similar activity during the year ended December 31, 2015 . As of December 31, 2017 , there was $423.8 million of total unrecognized compensation cost related to outstanding stock options and restricted stock awards that is expected to be recognized over a weighted average period of 2.80 years .

NET LOSS PER SHARE

NET LOSS PER SHARE	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
NET LOSS PER SHARE	NET LOSS PER SHARE Basic net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period. For the year ended December 31, 2015, net loss attributable to common stockholders includes the impact of the issuance of 10,299,696 shares of the Company's common stock to certain holders of Series E preferred stock, in the form of a deemed stock dividend of $ 32.2 million . Diluted loss per share is the same as basic loss per share for all years presented because the effects of potentially dilutive items were anti-dilutive given the Company’s net loss attributable to common stockholders. The following table presents the calculation of basic and diluted net loss per share (in thousands, except per share data): Year Ended December 31, 2017 2016 2015 Net loss $ (62,813 ) $ (171,590 ) $ (179,817 ) Deemed dividend on Series E preferred stock — — (32,200 ) Net loss attributable to common stockholders $ (62,813 ) $ (171,590 ) $ (212,017 ) Basic shares: Weighted-average common shares outstanding 380,921 344,393 175,139 Weighted-average unvested shares (1,577 ) (2,838 ) (4,641 ) Weighted-average shares used to compute basic net loss per share 379,344 341,555 170,498 Diluted shares: Weighted-average shares used to compute diluted net loss per share 379,344 341,555 170,498 Loss per share attributable to common stockholders: Basic $ (0.17 ) $ (0.50 ) $ (1.24 ) Diluted $ (0.17 ) $ (0.50 ) $ (1.24 ) Additionally, since the Company expects to settle the principal amount of its outstanding Notes in cash, the Company uses the treasury stock method for calculating any potential dilutive effect of the conversion spread on diluted net income per share, if applicable. The conversion spread will have a dilutive impact on diluted net income per share of common stock when the average market price of the Company’s common stock for a given period exceeds the conversion price of $22.95 per share for the Notes. Because the Company has reported a net loss for all periods presented, diluted loss per share is the same as basic loss per share for those periods. The following potential common shares were excluded from the calculation of diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented (in thousands): Year Ended December 31, 2017 2016 2015 Stock options and restricted stock units 68,588 88,705 111,148 Common stock warrants 19,173 9,457 9,544 Unvested shares 1,300 1,892 3,420 Employee stock purchase plan 157 216 172 Total anti-dilutive securities 89,218 100,270 124,284

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Operating and Capital Leases The Company has entered into various non-cancelable operating leases for certain offices with contractual lease periods expiring between 2018 and 2025 . The Company recognized total rental expenses under operating leases of $12.9 million , $11.3 million , and $12.8 million during the years ended December 31, 2017 , 2016 , and 2015 , respectively. Future minimum lease payments under non-cancelable operating leases (with initial lease terms in excess of one year) and future minimum capital lease payments as of December 31, 2017 are as follows (in thousands): Capital Operating Year: 2018 $ 2,656 $ 18,740 2019 2,540 17,438 2020 1,265 17,374 2021 35 16,968 2022 — 16,987 Thereafter — 19,383 Total $ 6,496 $ 106,890 Less amount representing interest (14 ) Present value of capital lease obligations 6,482 Less current portion of capital lease obligation (2,650 ) Non-current portion of capital lease obligation $ 3,832 Litigation The Company is currently a party to, and may in the future be involved in, various litigation matters (including intellectual property litigation), legal claims, and government investigations. The Company was involved in a class action lawsuit concerning independent contractors in connection with the Company’s Caviar business. On March 19, 2015, Jeffry Levin, on behalf of a putative nationwide class, filed a lawsuit in the United States District Court for the Northern District of California against the Company’s wholly owned subsidiary, Caviar, Inc., which, as amended, alleged that Caviar misclassified Mr. Levin and other similarly situated couriers as independent contractors and, in doing so, violated various provisions of the California Labor Code and California Business and Professions Code by requiring them to pay various business expenses that should have been borne by Caviar. The Court compelled arbitration of Mr. Levin’s individual claims on November 16, 2015 and dismissed the lawsuit in its entirety with prejudice on May 2, 2016. On June 1, 2016, Mr. Levin filed a Notice of Appeal of the Court’s order compelling arbitration with the United States Court of Appeals for the Ninth Circuit. Mr. Levin filed his opening appellate brief regarding the order compelling arbitration of his individual claims on October 7, 2016. The Company filed its answering brief on December 7, 2016, and Mr. Levin filed his reply on December 21, 2016. No hearing date was set. Mr. Levin also sought an award of penalties pursuant to the Labor Code Private Attorneys General Act of 2004 (PAGA). The parties stipulated that Mr. Levin would no longer pursue this PAGA claim but that it may instead be pursued by a different courier. Subsequently, couriers Nadezhda Rosen and La’Dell Brewster filed a new PAGA-only claim in the Superior Court of the State of California for the County of San Francisco (Superior Court) on November 7, 2016. Plaintiffs claimed that Caviar misclassified its couriers as independent contractors resulting in numerous violations of the California Labor Code, pursuant to which plaintiffs sought statutory penalties for those violations. In February 2017, the Company participated in a mediation with the parties in these Caviar misclassification suits to explore resolution of the matters at hand. After continued negotiation, the parties reached a global settlement of these suits, which has been confirmed. As a result, the Levin and Rosen lawsuits were dismissed with prejudice in their respective courts on January 24, 2018 and January 18, 2018, respectively. The Company has received a Notice of Tax Audit Deficiency (“Notice”) from the Office of the Treasurer & Tax Collector of the City and County of San Francisco (“Tax Collector”), for fiscal years 2014 and 2015, informing the Company that the Tax Collector believes the Company’s primary business activity is financial services rather than information services, and accordingly the Company would be liable for the Gross Receipts Tax and Payroll Expense Tax under the rules for financial services business activities. The demand Notice is for an immaterial amount and the Company is challenging the Notice and intends to vigorously defend its position, which it believes has merit. Should the Tax Collector prevail, the Company could be obligated to pay additional taxes together with any associated penalties and interest for subsequent years that together, in aggregate, could be material. The Company is currently unable to estimate the range of possible loss given the uncertainties associated with this matter, including uncertainties about the Tax Collector’s rationale for its position and about the amounts that may ultimately be subject to such taxes. In addition, from time to time, the Company is involved in various other litigation matters and disputes arising in the ordinary course of business. The Company cannot at this time fairly estimate a reasonable range of exposure, if any, of the potential liability with respect to these other matters. While the Company does not believe, at this time, that any ultimate liability resulting from any of these other matters will have a material adverse effect on the Company's results of operations, financial position, or liquidity, the Company cannot give any assurance regarding the ultimate outcome of these other matters, and their resolution could be material to the Company's operating results for any particular period.

SEGMENT AND GEOGRAPHICAL INFORM

SEGMENT AND GEOGRAPHICAL INFORMATION	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
SEGMENT AND GEOGRAPHICAL INFORMATION	SEGMENT AND GEOGRAPHICAL INFORMATION Operating segments are defined as components of an enterprise for which discrete financial information is available that is evaluated regularly by the chief operating decision maker (CODM) for purposes of allocating resources and evaluating financial performance. The Company’s CODM is the chief executive officer who reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. As such, the Company’s operations constitute a single operating segment and one reportable segment. Revenue Revenue by geography is based on the billing addresses of the merchants. The following table sets forth revenue by geographic area (in thousands): Year Ended December 31, 2017 2016 2015 Revenue United States $ 2,120,088 $ 1,643,852 $ 1,224,566 International 94,165 64,869 42,552 Total net revenue $ 2,214,253 $ 1,708,721 $ 1,267,118 No individual country from the international markets contributed in excess of 10% of total revenue for the years ended December 31, 2017 , 2016 , and 2015 . Long-Lived Assets The following table sets forth long-lived assets by geographic area (in thousands): December 31, 2017 2016 Long-lived assets United States $ 158,820 $ 162,118 International 5,337 2,675 Total long-lived assets $ 164,157 $ 164,793

SUPPLEMENTAL CASH FLOW INFORMAT

SUPPLEMENTAL CASH FLOW INFORMATION	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
SUPPLEMENTAL CASH FLOW INFORMATION	SUPPLEMENTAL CASH FLOW INFORMATION The supplemental disclosures of cash flow information consist of the following (in thousands): Year Ended December 31, 2017 2016 2015 Supplemental Cash Flow Data: Cash paid for interest $ 1,374 $ 570 $ 981 Cash paid for income taxes 1,254 395 1,916 Supplemental disclosures of non-cash investing and financing activities: Change in purchases of property and equipment in accounts payable and accrued expenses 143 2,554 5,593 Unpaid business acquisition purchase price 2,115 240 — Conversion of Series A, B, C, D & E preferred stock upon initial public offering to common stock — — 544,897 Unpaid offering costs related to initial public offering — — 5,530 Deemed dividend on Series E preferred stock — — 32,200 Fair value of shares issued related to acquisitions — — 35,776

DESCRIPTION OF BUSINESS AND S24

DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reclassifications and Other Adjustments	Reclassifications and Other Adjustments As a result of the Company’s adoption of Accounting Standards Update (ASU) No. 2016-18, Restricted Cash, on January 1, 2017, the Company reclassified changes in restricted cash balances from investing activities in the statement of cash flows to changes in cash, cash equivalents and restricted cash. For the years ended December 31, 2016 and 2015, $8.5 million and $1.9 million , respectively, was reclassified from cash outflows from investing activities to changes in cash, cash equivalents and restricted cash. During the year ended December 31, 2017, the Company has reclassified certain prior period balances to conform to the current period presentation. In particular the Company has combined the Customer funds obligation and Customers payable into a single caption called Customers payable on the consolidated balance sheet. This classification change was made because both accounts reflect customer amounts that are held by Square that are obligations to the customer.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) and include the accounts of the Company and its subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, as well as related disclosure of contingent assets and liabilities. Actual results could differ from the Company’s estimates. To the extent that there are material differences between these estimates and actual results, the Company’s financial condition or operating results will be materially affected. The Company bases its estimates on past experience and other assumptions that the Company believes are reasonable under the circumstances, and the Company evaluates these estimates on an ongoing basis. Estimates, judgments, and assumptions in these consolidated financial statements include, but are not limited to, those related to revenue recognition, accrued transaction losses, valuation of the debt component of convertible senior notes, valuation of loans held for sale, goodwill and intangible assets, income and other taxes, and share-based compensation.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery of obligations to its customers has occurred, the related fees are fixed or determinable, and collectibility is reasonably assured. Revenue is generated from the following: Transaction-based revenue and Starbucks transaction-based revenue The Company charges its sellers a transaction fee for managed payments solutions that is generally calculated as a percentage of the total transaction amount processed. The Company selectively offers custom pricing for certain sellers. The Company had a processing agreement with Starbucks, for certain Starbucks-owned stores in the United States. During the fourth quarter of 2016, Starbucks completed its previously announced transition to another payments solution provider. The Company recognizes the transaction fees a seller pays to the Company as revenue upon authorization of a transaction by the seller's customer's bank. Revenue is recognized net of refunds, which arise from reversals of transactions initiated by sellers. The Company acts as the merchant of record for its sellers and works directly with payment card networks and banks so that its sellers do not need to manage the complex systems, rules, and requirements of the payments industry. As the merchant of record, Square is liable for settlement of the transactions the Company processes for its sellers. The gross transaction fees collected from sellers are recognized as revenue on a gross basis as the Company is the primary obligor to the seller and is responsible for processing the payment, has latitude in establishing pricing with respect to the sellers and other terms of service, has sole discretion in selecting the third party to perform the settlement, and assumes the credit risk for the transaction processed. Subscription and services-based revenue Subscription and services-based revenue is primarily generated by Instant Deposit, Caviar, Square Capital and various software as a service products. Instant Deposit is a functionality within the Cash App and the Company's managed payment solutions that enables customer to instantly deposit funds into their bank accounts. The Company charges a per transaction fee which we recognize as revenue when customers instantly deposit funds to their bank account. Caviar is a food ordering platform that facilitates food delivery services for restaurants. Caviar revenue consists of fees charged to restaurants, as sellers, and delivery and service fees charged to customers. All fees are recognized upon delivery of the food, net of refunds. Square Capital facilitates a loan that is offered through a partnership with an industrial bank that is generally repaid through withholding a percentage of the collections of the seller's receivables processed by the Company. During the first quarter of 2016, the Company fully transitioned from offering merchant cash advances (MCAs) to loans. The Company facilitates loans to sellers pre-qualified through an analysis of the aggregated data of the seller’s business which includes, but is not limited to, the seller’s historical processing volumes, transaction count, chargebacks, growth, and length of time as a Square customer. The loans are originated by a bank partner, from whom the Company purchases the loans obtaining all rights, title, and interest. The loans have no stated coupon rate but the seller is charged a one-time origination fee by the bank partner based upon their risk rating, which is derived primarily from processing activity. It is the Company’s intent to sell all of its rights, title, and interest of these loans to third-party investors for an upfront fee when the loans are sold. The Company records the net amounts paid to the bank as the cost of the loans purchased and subsequently records a gain on sale of the loans to the third-party investors. The Company is retained by the third-party investors to service the loans and earns a servicing fee for facilitating the repayment of these receivables through its payments solutions. The Company recognizes the gain on sale of the loans to the investors as revenue upon transfer of title to investors. The Company records servicing revenue as servicing is delivered. For the loans which are not sold to third-party investors, the Company recognizes a portion of the expected seller repayments over the cost of the loans as revenue in proportion to the loan principal reduction. Software as a service provides customers with access to various technologies for a fee which is recognized ratably as the service is provided.
Hardware revenue	Hardware revenue Hardware revenue is generated from sales of contactless and chip readers, chip card readers, Square Stand, Square Register and third-party peripherals. Hardware revenue is recorded net of returns and is recognized upon delivery of hardware to the end customer and satisfaction of the other basic revenue recognition criteria. The Company considers delivery to have occurred once title and risk of loss has been transferred to the end customer. The Company records deferred revenue when it receives payments in advance of the delivery of products.
Cost of Revenue	Cost of Revenue Transaction-based costs and Starbucks transaction-based costs Transaction-based costs and Starbucks transaction-based costs consist primarily of interchange and assessment fees, processing fees and bank settlement fees paid to third-party payment processors and financial institutions. Contracts with third-party payment processors are typically for a term of two to four years. Subscription and services-based costs Subscription and services-based costs consist primarily of Caviar-related costs, which include payments to third-party couriers for deliveries and the cost of equipment provided to sellers. These costs also include costs associated with Cash App transactions when customers instantly deposit funds to their bank account and for transactions conducted with a Cash Card, credit card or Cash for Business. Cost of revenue for other subscription and services-based costs consists primarily of the amortization related to the development of certain subscription and services-based products. Hardware costs Hardware costs consist of all product costs associated with contactless and chip readers, chip card readers, Square Stand, Square Register and third-party peripherals. Product costs include manufacturing-related overhead and personnel costs, certain royalties, packaging, and fulfillment costs.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred and included in sales and marketing expense on the consolidated statements of operations.
Share-based Compensation	Share-based Compensation Share-based compensation expense relates to stock options, restricted stock units (RSUs), and purchases under the Company’s 2015 Employee Stock Purchase Plan (ESPP) which is measured based on the grant-date fair value. The fair value of RSUs is determined by the closing price of the Company’s common stock on each grant date.The fair value of stock options and employee stock purchase plan shares granted to employees is estimated on the date of grant using the Black-Scholes-Merton option valuation model. This share-based compensation expense valuation model requires the Company to make assumptions and judgments regarding the variables used in the calculation. These variables include the expected term (weighted average period of time that the options granted are expected to be outstanding), the expected volatility of the Company’s stock, expected risk-free interest rate and expected dividends. The Company uses the simplified calculation of expected term, as the Company does not have sufficient historical data to use any other method to estimate expected term. Expected volatility is based on a weighted average of the historical volatilities of the Company's common stock along with several entities with characteristics similar to those of the Company. The Company will continue to weight its own volatility more heavily as more of its own historical stock price information becomes available. Once its own historical data is equal to that of the expected term of option grants a peer group is no longer considered necessary. The expected risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. Share-based compensation expense is recorded on a straight-line basis over the requisite service period. For the year ended December 31, 2016 and prior, the Company recorded share-based compensation expense net of estimated forfeitures. On January 1, 2017, as a result of the Company's adoption of ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , the Company elected to account for forfeitures as they occur. The fair value of stock options granted to non-employees, including consultants, is initially measured upon the date of grant and remeasured over the vesting period using the same methodology described above. These non-employees provide service to the Company on an ongoing basis, therefore, the performance commitment for each non-employee grant is not considered probable until the award is earned over time. The expected term for non-employee grants is the contractual term and share-based compensation expense is recognized on a straight-line basis over this term. Share-based compensation expense related to non-employees has not been material for any of the periods presented.
Income and Other Taxes	Income and Other Taxes The Company reports income taxes under the asset and liability approach. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, as well as net operating loss and tax credit carryforwards. Deferred tax amounts are determined by using the enacted tax rates expected to be in effect when the temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance reduces the deferred tax assets to the amount that is more likely than not to be realized. The Company uses financial projections to support its net deferred tax assets, which contain significant assumptions and estimates of future operations. If such assumptions were to differ significantly from actual future results of operations, it may have a material impact on the Company’s ability to realize its deferred tax assets. At the end of each period, the Company assesses the ability to realize the deferred tax assets. If it is more likely than not that the Company would not realize the deferred tax assets, then the Company would establish a valuation allowance for all or a portion of the deferred tax assets. The Company recognizes the effect of uncertain income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that has a greater than 50% likelihood of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company records interest and penalties related to uncertain tax positions in the provision for income tax expense on the consolidated statements of operations.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents and Restricted Cash The Company considers all highly liquid investments, including money market funds, with an original maturity of three months or less when purchased to be cash equivalents. As of December 31, 2017 and 2016 , restricted cash of $28.8 million and $22.1 million , respectively, is related to pledged cash deposited into savings accounts at the financial institutions that process the Company's sellers' payment transactions and as collateral pursuant to an agreement with the originating bank for the Company's loan product. The Company uses the restricted cash to secure letters of credit with the financial institution to provide collateral for cash flow timing differences in the processing of these payments. The Company has recorded this amount as a current asset on the consolidated balance sheets due to the short-term nature of these cash flow timing differences and that there is no minimum time frame during which the cash must remain restricted. Additionally, this balance includes certain amounts held as collateral pursuant to multi-year lease agreements, discussed in the paragraph below, which we expect to become unrestricted within the next year. As of December 31, 2017 and 2016 , the remaining restricted cash of $9.8 million and $14.6 million , respectively, is primarily related to cash deposited into money market funds that is used as collateral pursuant to multi-year lease agreements entered into in 2012 and 2014 (Note 14 ). The Company has recorded this amount as a non-current asset on the consolidated balance sheets as the terms of the related leases extend beyond one year.
Concentration of Credit Risk	Concentration of Credit Risk For the years ended December 31, 2017 and 2016 , the Company had no customer who accounted for greater than 10% of total net revenue. For the year ended December 31, 2015 , the Company had no customer other than Starbucks who accounted for greater than 10% of total net revenue. The Company terminated its relationship with Starbucks during the year ended December 31, 2016. The Company had three third-party payment processors that represented approximately 46% , 42% , and 8% of settlements receivable as of December 31, 2017 . The same three parties represented approximately 52% , 35% , and 10% of settlements receivable as of December 31, 2016 . All other third-party processors were insignificant. Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash, marketable securities, settlements receivables, customer funds, and loans held for sale. The associated risk of concentration for cash and cash equivalents and restricted cash is mitigated by banking with creditworthy institutions. At certain times, amounts on deposit exceed federal deposit insurance limits. The associated risk of concentration for marketable securities is mitigated by holding a diversified portfolio of highly rated investments. Settlements receivable are amounts due from well-established payment processing companies and normally take one or two business days to settle which mitigates the associated risk of concentration. The associated risk of concentration for loans held for sale is partially mitigated by credit evaluations that are performed prior to facilitating the offering of loans and ongoing performance monitoring of the Company’s loan customers.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. Fair value accounting establishes a three-level hierarchy priority for disclosure of assets and liabilities recorded at fair value. The ordering of priority reflects the degree to which objective prices in external active markets are available to measure fair value. The classification of assets and liabilities within the hierarchy is based on whether the inputs to the valuation methodology used for measurement are observable or unobservable. The Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Company determines fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels: • Level 1 Inputs: Unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date. • Level 2 Inputs: Other than quoted prices included in Level 1 Inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability. • Level 3 Inputs: Unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at measurement date.
Loans Held for Sale	Loans Held for Sale The Company classifies customer loans as held for sale upon purchase from a bank partner, as there is an available market for such loans and it is the Company’s intent to sell all of its rights, title, and interest in these loans to third-party investors. Loans held for sale are recorded at the lower of amortized cost or fair value determined on an individual loan basis. To determine the fair value the Company utilizes industry-standard valuation modeling, such as discounted cash flow models, taking into account the estimated timing and amounts of periodic repayments. The Company recognizes a charge within transaction, loan and advance losses on the consolidated statement of operations whenever the amortized cost of a loan exceeds its fair value, with such charges being reversed for subsequent increases in fair value, but only to the extent that such reversals do not result in the amortized cost of a loan exceeding its fair value. A loan that is initially designated as held for sale may be reclassified to held for investment if and when the Company's intent for that loan changes. There have been no reclassifications made to date.
Settlement Receivable	Settlements Receivable Settlements receivable represents amounts due from third-party payment processors for customer transactions. Settlements receivable are typically received within one or two business days of the transaction date. No valuation allowances have been established, as funds are due from large, well-established financial institutions with no historical collections issue.
Customer Funds	Customer Funds Customer funds held represent Cash App customers' stored balances that customers would later use to send money or make payments, or customers cash in transit. As of December 31, 2017 and 2016 , the Company held these stored balances as short term bank deposits.
Inventory	Inventory Inventory is comprised of contactless and chip readers, chip card readers, Square Stand, Square Register and third-party peripherals, as well as component parts that are used to manufacture these products. Inventory is stated at the lower of cost (generally on a first-in, first-out basis) or net realizable value. Inventory that is obsolete or in excess of forecasted usage is written down to its net realizable value based on the estimated selling prices in the ordinary course of business. The Company's inventory is held at the Company's warehouses as well as at third party contract manufacturer premises.
Deferred Magstripe Reader Costs	Deferred Magstripe Reader Costs The Company capitalizes the cost of its magstripe readers, which are included in other current assets on the consolidated balance sheets. The amount capitalized represents the cost of the readers, including packaging and shipping costs, held on-hand by the Company as of each consolidated balance sheet date. Once the readers are shipped to a third-party distributor or an end-customer, they are recorded as marketing expense on the consolidated statements of operations.
Property and Equipment	Property and Equipment Property and equipment are recorded at historical cost less accumulated depreciation, which is computed on a straight-line basis over the asset’s estimated useful life. The estimated useful lives of property and equipment are described below: Property and Equipment Useful Life Capitalized software 18 months Computer and data center equipment Three years Furniture and fixtures Seven years Leasehold improvements Lesser of estimated useful life or remaining lease term When assets are retired or otherwise disposed of, the cost and related accumulated depreciation are removed from their respective accounts, and any gain or loss on such sale or disposal is reflected in operating expenses.
Capitalized Software	Capitalized Software The Company capitalizes certain cost incurred in developing internal-use software when capitalization requirements have been met. Costs prior to meeting the capitalization requirements are expensed as incurred. Capitalized costs are included in property and equipment, net, and amortized on a straight-lined basis over the estimated useful life of the software and included in product development costs or allocated to subscription and service-based costs on the consolidated statements of operations.
Leases	Leases The Company leases office space and equipment under non-cancellable capital and operating leases with various expiration dates. The Company records the total rent expense on a straight-line basis over the lease term. When lease agreements provide allowances for leasehold improvements, the Company capitalizes the leasehold improvement assets and recognizes the related depreciation expense on a straight-line basis over the lesser of the lease term or the estimated useful life of the asset, and reduces rent expense on a straight-line basis over the term of the lease by the amount of the allowances provided. The Company classifies the cash payments for the leasehold improvements within investing activities while reimbursements from the landlords are classified within operating activities.
Asset Retirement Obligations	The Company records a liability for the estimated fair value for any asset retirement obligation (ARO) associated with its leases, with an offsetting asset. In the determination of the fair value of AROs, the Company uses various assumptions and judgments, including such factors as the existence of a legal obligation, estimated amounts and timing of settlements, and discount and inflation rates. The liability is subsequently accreted while the asset is depreciated.
Business Combinations	Business Combinations The purchase price of an acquisition is allocated to the tangible and intangible assets acquired and liabilities assumed based on their estimated fair values at the acquisition dates. The excess of total consideration over the fair values of the assets acquired and the liabilities assumed is recorded as goodwill. During the measurement period, which may be up to one year from the acquisition date, the Company may record adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments would be recorded on the consolidated statements of operations.
Long-lived Assets, including Goodwill and Acquired Intangibles	Long-Lived Assets, including Goodwill and Acquired Intangibles The Company evaluates the recoverability of property and equipment and finite lived intangible assets for impairment whenever events or circumstances indicate that the carrying amounts of such assets may not be recoverable. Recoverability is measured by comparing the carrying amount of an asset or an asset group to estimate undiscounted future net cash flows expected to be generated. If the carrying amount of the long–lived asset or asset group is not recoverable on an undiscounted cash flow basis, an impairment is recognized to the extent that the carrying amount exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values, and third–part independent appraisals, as considered necessary. For the periods presented, the Company had recorded no impairment charges. Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired in a business combination. The Company performs a goodwill impairment test annually on December 31 and more frequently if events and circumstances indicate that the asset might be impaired. An impairment loss is recognized to the extent that the carrying amount exceeds the reporting unit’s fair value. The Company has the option to first assess qualitative factors to determine whether events or circumstances indicate that it is more likely than not that the fair value of a reporting unit is less than its carrying amount and determine whether further action is needed. If, after assessing the totality of events or circumstances, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. For the periods presented, the Company had recorded no impairment charges. Acquired intangibles consist of acquired technology and customer relationships associated with various acquisitions. Acquired technology is amortized over its estimated useful life on a straight-line basis within cost of revenue. Customer relationships acquired are amortized on a straight-line basis over their estimated useful lives within operating expenses. The Company evaluates the remaining estimated useful life of its intangible assets being amortized on an ongoing basis to determine whether events and circumstances warrant a revision to the remaining period of amortization.
Customers Funds and Payables	Customers Payable Customers payable represents the transaction amounts, less revenue earned by the Company, owed to sellers or Cash App customers. The payable amount comprises amounts owed to customers due to timing differences as we typically settle within one business day, amounts held by the Company in accordance with its risk management policies, and amounts held for customers who have not yet linked a bank account. This balance also includes the Company's liability for customer funds held on the Cash App.
Accrued Transaction Losses	Accrued Transaction Losses The Company establishes a reserve for estimated transaction losses due to chargebacks, which represent a potential loss due to disputes between a seller and their customer or due to a fraudulent transaction. The reserve is estimated based on available data as of the reporting date, including expectations of future chargebacks, and historical trends related to loss rates. Additions to the reserve are reflected in current operating results, while charges to the reserve are made when losses are recognized. These amounts are classified within transaction and advance losses on the consolidated statements of operations.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers , and issued subsequent amendments to the initial guidance within ASU 2015-04, ASU 2016-08, ASU 2016-10, ASU 2016-12, and ASU 2016-20. The new guidance will replace all current U.S. GAAP guidance about revenue recognition, including industry specific guidance. The core principal of this new guidance is that revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration for which the Company expects to be entitled in exchange for those goods or services. The new guidance will also change how companies account for certain incremental costs to obtain a customer contract, such as sales commissions, by requiring that such costs be capitalized and charged to expense over the period of expected benefit. This guidance is effective for the Company’s interim and annual financial statements beginning January 1, 2018. The guidance can be adopted either through the full retrospective approach, which requires restatement of all periods presented with a cumulative effect adjustment as of the beginning of the earliest period presented, or through a modified retrospective approach, which requires a cumulative effect adjustment as of the date of adoption. The modified retrospective approach also requires additional disclosures, for the year of adoption, of the impact of the new guidance to each of the financial statements line items and qualitative explanation of the significant changes between the reported results under the new revenue guidance and the previous revenue guidance. The Company adopted this new guidance on January 1, 2018 using the modified retrospective approach. Apart from the incremental disclosure requirements it is the Company’s conclusion that the new guidance will not have a material impact on its consolidated financial statements, financial reporting systems, processes or controls. In July 2015, the FASB issued ASU No. 2015-11, Simplifying the Measurement of Inventory, as part of its simplification initiative. The previous guidance required an entity to measure inventory at the lower of cost or market. Market could be replacement cost, net realizable value, or net realizable value less a normal profit margin. Under the new guidance, inventory is measured at the lower of cost and net realizable value, which would eliminate the other two options that currently exist for market replacement cost and net realizable value less a normal profit margin. The amendment is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years, with early adoption permitted. The Company adopted this new guidance on January 1, 2017, and it did not have any effect on the consolidated financial statements and related disclosures. In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities. This guidance is intended to improve the recognition, measurement, presentation, and disclosure of financial instruments. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted with certain restrictions. The new guidance could result to volatility of other income (expense), net, in future periods as a result of the remeasurement of the equity securities through earnings upon the occurrence of future observable price changes. The Company adopted this new guidance on January 1, 2018, and it did not have any effect on the consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases , which will require, among other items, lessees to recognize a right of use asset and a related lease liability for most leases on the balance sheet. Qualitative and quantitative disclosures will be enhanced to better understand the amount, timing and uncertainty of cash flows arising from leases. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. The Company does not plan to early adopt this guidance. The Company’s operating leases primarily comprise of office spaces, with the most significant leases relating to corporate headquarters in San Francisco and an office in New York. While the Company continues to evaluate the impact of adopting this guidance on its consolidated financial statements, it does expect to record right to use assets and related lease liabilities on its consolidated balance sheets upon adoption, which will increase total assets and liabilities. In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , which is intended to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years, with early adoption permitted. The Company adopted this new guidance on January 1, 2017. As part of the adoption, the Company elected to account for forfeitures as they occur. As this guidance requires a modified retrospective approach when eliminating the forfeiture rate, the Company recorded an adjustment of $0.7 million to increase accumulated deficit and additional paid-in capital as of January 1, 2017. With respect to classification of excess tax benefits on the Statement of Cash Flows, the Company has elected to apply this guidance on a prospective basis. Thus, the prior periods have not been adjusted. The remaining areas of simplification in this guidance did not have an impact on the consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments , which requires measurement and recognition of expected credit losses for financial assets held. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact this new guidance may have on the consolidated financial statements and related disclosures. In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments. This guidance addresses several cash flow issues with the objective of reducing the existing diversity in practice. Specific issues addressed in this guidance include, but are not limited to, debt prepayment or extinguishment costs, contingent consideration payments made after a business combination and application of the predominance principle. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. The amendments should be applied retrospectively. The Company adopted this new guidance on January 1, 2018, and it did not have any effect on the consolidated financial statements and related disclosures. In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Transfers of Assets Other Than Inventory , which amends existing guidance on the recognition of current and deferred income tax impacts for intra-entity asset transfers other than inventory. The current guidance requires companies to defer the income tax effects of intercompany transfers of all assets, until the asset has been sold to an outside party whereas the new guidance will not allow the deferral of income tax effects of intercompany transfers of assets except for inventory. This standard is effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. The amendments in this guidance should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company adopted this new guidance on January 1, 2018, and it did not have any effect on the consolidated financial statements and related disclosures. In November 2016, the FASB issued ASU No. 2016-18, Restricted Cash , which provides guidance on the classification of restricted cash to be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts on the statement of cash flows. This standard is effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. The Company early adopted this guidance on January 1, 2017, and adjusted its consolidated statements of cash flow for each of the periods presented. In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business . The amendment seeks to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill, intangible assets and consolidation. This standard is effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. The amendments should be applied prospectively on or after the effective dates. The Company adopted this new guidance on January 1, 2018, and it did not have any effect on the consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairment . The new guidance eliminates the requirement to calculate the implied fair value of goodwill assuming a hypothetical purchase price allocation (i.e., Step 2 of the goodwill impairment test) to measure a goodwill impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value, not to exceed the carrying amount of goodwill. This standard should be adopted when the Company performs its annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019, with early adoption permitted. The amendments should be applied on a prospective basis. The Company does not expect the adoption of this guidance to have a material the impact on the consolidated financial statements and related disclosures. In March 2017, the FASB issued ASU No. 2017-08, Premium Amortization on Purchased Callable Debt Securities, which amends the amortization period for certain purchased callable debt securities held at a premium, shortening such period to the earliest call date. This standard is effective for annual periods beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. The amendments in this guidance should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact this new guidance may have on the consolidated financial statements and related disclosures. In May 2017, the FASB issued ASU No. 2017-09, Scope of Modification Accounting, which clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. This standard is effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. The amendments should be applied on a prospective basis. The Company adopted this new guidance on January 1, 2018, and it did not have any effect on the consolidated financial statements and related disclosures.

DESCRIPTION OF BUSINESS AND S25

DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Estimated Useful Lives of Property and Equipment	The estimated useful lives of property and equipment are described below: Property and Equipment Useful Life Capitalized software 18 months Computer and data center equipment Three years Furniture and fixtures Seven years Leasehold improvements Lesser of estimated useful life or remaining lease term The following is a summary of property and equipment, less accumulated depreciation and amortization (in thousands): December 31, December 31, Computer equipment $ 66,186 $ 52,915 Office furniture and equipment 14,490 10,737 Leasehold improvements 77,073 73,366 Capitalized software 35,063 24,642 Total 192,812 161,660 Less: Accumulated depreciation and amortization (101,316 ) (73,332 ) Property and equipment, net $ 91,496 $ 88,328

FAIR VALUE OF FINANCIAL INSTR26

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The Company’s financial assets and liabilities that are measured at fair value on a recurring basis are classified as follows (in thousands): December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Cash and cash equivalents: Money market funds $ 387,698 $ — $ — $ 207,168 $ — $ — Commercial paper — 24,695 — — 7,496 — Municipal securities — — — — 1,000 — Short-term securities: U.S. agency securities — 15,083 — — 9,055 — Corporate bonds — 57,798 — — 6,980 — Commercial paper — 17,428 — — 17,298 — Municipal securities — 23,700 — — 8,028 — U.S. government securities 55,567 — — 18,540 — — Long-term securities: U.S. agency securities — 20,169 — — 3,502 — Corporate bonds — 91,413 — — 12,914 — Municipal securities — 26,224 — — 2,492 — U.S. government securities 65,861 — — 8,458 — — Total $ 509,126 $ 276,510 $ — $ 234,166 $ 68,765 $ — The estimated fair value and carrying value of the convertible senior notes were as follows (in thousands): December 31, 2017 Carrying Value Fair Value (Level 2) Convertible senior notes $ 358,572 $ 719,356 Total $ 358,572 $ 719,356 A summary of loans disclosed at fair value on a recurring basis is as follows (in thousands): December 31, 2017 December 31, 2016 Carrying Value Fair Value (Level 3) Carrying Value Fair Value (Level 3) Loans held for sale $ 73,420 $ 76,070 $ 42,144 $ 42,633 Total $ 73,420 $ 76,070 $ 42,144 $ 42,633

INVESTMENTS (Tables)

INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Short-term and Long-term Investments	The Company's short-term and long-term investments as of December 31, 2017 are as follows (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term securities: U.S. agency securities $ 15,122 $ — $ (39 ) $ 15,083 Corporate bonds 57,855 22 (79 ) 57,798 Commercial paper 17,428 — — 17,428 Municipal securities 23,743 8 (51 ) 23,700 U.S. government securities 55,729 1 (163 ) 55,567 Total $ 169,877 $ 31 $ (332 ) $ 169,576 Long-term securities: U.S. agency securities $ 20,288 $ 2 $ (121 ) $ 20,169 Corporate bonds 91,959 25 (571 ) 91,413 Municipal securities 26,371 13 (160 ) 26,224 U.S. government securities 66,362 19 (520 ) 65,861 Total $ 204,980 $ 59 $ (1,372 ) $ 203,667 The Company's short-term and long-term investments as of December 31, 2016 are as follows (in thousands): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Short-term securities: U.S. agency securities $ 9,048 $ 7 $ — $ 9,055 Corporate bonds 17,318 — (20 ) 17,298 Commercial paper 6,980 — — 6,980 Municipal securities 8,037 — (9 ) 8,028 U.S. government securities 18,537 3 — 18,540 Total $ 59,920 $ 10 $ (29 ) $ 59,901 Long-term securities: U.S. agency securities $ 3,502 $ — $ — $ 3,502 Corporate bonds 12,939 — (25 ) 12,914 Municipal securities 2,505 — (13 ) 2,492 U.S. government securities 8,478 — (20 ) 8,458 Total $ 27,424 $ — $ (58 ) $ 27,366
Investments Classified by Contractual Maturity Date	The contractual maturities of the Company's short-term and long-term investments as of December 31, 2017 are as follows (in thousands): Amortized Cost Fair Value Due in one year or less $ 169,877 $ 169,576 Due in one to five years 204,980 203,667 Total $ 374,857 $ 373,243

PROPERTY AND EQUIPMENT, NET (Ta

PROPERTY AND EQUIPMENT, NET (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Summary of Property, Equipment and Internally-Developed Software	The estimated useful lives of property and equipment are described below: Property and Equipment Useful Life Capitalized software 18 months Computer and data center equipment Three years Furniture and fixtures Seven years Leasehold improvements Lesser of estimated useful life or remaining lease term The following is a summary of property and equipment, less accumulated depreciation and amortization (in thousands): December 31, December 31, Computer equipment $ 66,186 $ 52,915 Office furniture and equipment 14,490 10,737 Leasehold improvements 77,073 73,366 Capitalized software 35,063 24,642 Total 192,812 161,660 Less: Accumulated depreciation and amortization (101,316 ) (73,332 ) Property and equipment, net $ 91,496 $ 88,328

ACQUIRED INTANGIBLE ASSETS (Tab

ACQUIRED INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite Lived Intangible Assets	The following table presents the detail of acquired intangible assets as of the periods presented (in thousands): Balance at December 31, 2017 Cost Accumulated Amortization Net Patents $ 1,285 $ (559 ) $ 726 Technology Assets 29,158 (21,329 ) 7,829 Customer Assets 10,319 (4,540 ) 5,779 Total $ 40,762 $ (26,428 ) $ 14,334 Balance at December 31, 2016 Cost Accumulated Amortization Net Patents $ 1,285 $ (454 ) $ 831 Technology Assets 29,075 (14,702 ) 14,373 Customer Assets 7,745 (3,657 ) 4,088 Total $ 38,105 $ (18,813 ) $ 19,292
Schedule of Annual Future Amortization Expense of Intangible Assets	The total estimated annual future amortization expense of these intangible assets as of December 31, 2017 , is as follows (in thousands): 2018 $ 6,226 2019 3,442 2020 1,479 2021 846 2022 611 Thereafter 1,730 Total $ 14,334

OTHER CONSOLIDATED BALANCE SH30

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (CURRENT) (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other Current Assets	The following table presents the detail of other current assets (in thousands): December 31, December 31, Inventory, net $ 16,777 $ 13,724 Processing costs receivable 21,083 10,049 Prepaid expenses 14,473 7,365 Accounts receivable, net 8,606 6,191 Deferred hardware costs 7,931 4,546 Deferred magstripe reader costs 2,469 3,911 Merchant cash advance receivable, net 125 4,212 Other 14,990 10,545 Total $ 86,454 $ 60,543
Accrued Expenses	The following table presents the detail of accrued expenses (in thousands): December 31, December 31, Accrued payroll $ 9,103 $ 5,799 Accrued professional fees 5,638 5,788 Accrued advertising and other marketing 6,723 5,008 Processing costs payable 10,145 10,871 Accrued non income tax liabilities 6,155 3,562 Accrued hardware costs 2,496 3,148 Other accrued liabilities $ 12,020 $ 5,367 Total $ 52,280 $ 39,543
Other Current Liabilities	The following table presents the detail of other current liabilities (in thousands): December 31, December 31, Square Capital payable (i) $ 7,671 $ 4,907 Square Payroll payable (ii) 2,850 4,769 Deferred revenue 5,893 5,407 Current portion of deferred rent 3,311 2,862 Accrued redemptions 1,036 1,628 Other 7,606 2,899 Total $ 28,367 $ 22,472 (i) Square Capital payable represents unpaid amounts arising from the purchase of loans or loan repayments collected on behalf of third parties. (ii) Square Payroll payable represents amounts received from Square Payroll product customers that will be utilized to settle the customers employee payroll and related obligations.

OTHER CONSOLIDATED BALANCE SH31

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (NON-CURRENT) (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other Non-Current Assets	The following table presents the detail of other non-current assets (in thousands): December 31, December 31, Investment in privately held entity (i) $ 25,000 $ — Deposits 2,738 1,775 Debt issuance costs 788 1,063 Deferred tax assets 519 306 Other 2,305 50 Total $ 31,350 $ 3,194 (i) In August, 2017, the Company invested $25.0 million in Eventbrite, a leader in event technology providing a platform that facilitates ticket sales, as well as promotion and management of events. In conjunction with the investment, the Company entered into an agreement with Eventbrite specifying terms under which the Company would provide payment processing services to Eventbrite and its customers for a five year term in the countries in which the Company operates. This agreement is subject to automatic one year renewals thereafter unless terminated by either party. Eventbrite and the Company have a common member on their respective boards of directors. The Company has not estimated the fair value of the investment as it has determined that it is not practicable to determine such fair value, and there are no identified events or changes in circumstances that may have a significant adverse effect on the fair value.
Other Non-Current Liabilities	The following table presents the detail of other non-current liabilities (in thousands): December 31, December 31, Statutory liabilities (ii) $ 40,768 $ 29,497 Deferred rent 20,349 23,119 Deferred tax liabilities 644 476 Other 7,777 4,653 Total $ 69,538 $ 57,745 (ii) Statutory liabilities represent loss contingencies that may arise from the Company's interpretation and application of certain guidelines and rules issued by various federal, state, local, and foreign regulatory authorities.

INDEBTEDNESS (Tables)

INDEBTEDNESS (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Convertible Notes	The Notes consisted of the following (in thousands): December 31, 2017 Principal $ 440,000 Less: unamortized debt discount (73,384 ) Less: unamortized debt issuance costs (8,044 ) Net carrying amount $ 358,572 The net carrying amount of the equity component of the Notes was as follows (in thousands): December 31, 2017 Debt discount related to value of conversion option $ 86,203 Less: allocated debt issuance costs (2,302 ) Equity component, net $ 83,901
Interest Expense on Convertible Notes	The Company recognized interest expense on the Notes as follows (in thousands, except for percentages): Year Ended December 31, 2017 Contractual interest expense based on 0.375% per annum 1,351 Amortization of debt discount and issuance costs 14,223 Total 15,574 Effective interest rate of the liability component 5.34 %

ACCRUED TRANSACTION LOSSES (Tab

ACCRUED TRANSACTION LOSSES (Tables)	12 Months Ended
	Dec. 31, 2017
Product Warranties Disclosures [Abstract]
Schedule of Reserve for Transaction Losses	The following table summarizes the activities of the Company’s reserve for transaction losses (in thousands): Year Ended December 31, 2017 2016 2015 Accrued transaction losses, beginning of the year $ 20,064 $ 17,176 $ 8,452 Provision for transaction losses 52,977 50,819 43,379 Charge-offs to accrued transaction losses (46,148 ) (47,931 ) (34,655 ) Accrued transaction losses, end of the year $ 26,893 $ 20,064 $ 17,176

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Domestic and Foreign Components of Loss Before Income Taxes	The domestic and foreign components of loss before income taxes are as follows (in thousands): Year Ended December 31, 2017 2016 2015 Domestic $ (10,900 ) $ (145,499 ) $ (157,229 ) Foreign (51,764 ) (24,174 ) (18,842 ) Loss before income taxes $ (62,664 ) $ (169,673 ) $ (176,071 )
Components of Provision for Income Taxes	The components of the provision for income taxes are as follows (in thousands): Year Ended December 31, 2017 2016 2015 Current: Federal $ (1,192 ) $ 63 $ 1,662 State 739 527 836 Foreign 1,987 1,269 1,222 Total current provision for income taxes 1,534 1,859 3,720 Deferred: Federal (1,169 ) 173 67 State 57 18 11 Foreign (273 ) (133 ) (52 ) Total deferred provision for income taxes (1,385 ) 58 26 Total provision for income taxes $ 149 $ 1,917 $ 3,746
Reconciliation of Statutory Federal Income Tax Rate to Company's Effective Tax Rate	The following is a reconciliation of the statutory federal income tax rate to the Company's effective tax rate: Balance at December 31, 2017 2016 2015 Tax at federal statutory rate 34.0 % 34.0 % 34.0 % State taxes, net of federal benefit (0.4 ) (0.1 ) (0.2 ) Foreign rate differential (14.9 ) (2.4 ) (1.8 ) Nondeductible expenses (1.0 ) (0.9 ) (1.1 ) Credits 41.5 8.5 8.2 Other items (1.2 ) 0.2 0.1 Change in valuation allowance (119.5 ) (37.4 ) (38.6 ) Impact of U.S. tax reform (209.1 ) — — Share-based compensation (i) 243.5 (2.4 ) (2.2 ) Change in uncertain tax positions (2.4 ) (0.6 ) (0.5 ) Termination of warrant 29.3 — — Total (0.2 )% (1.1 )% (2.1 )% (i) Starting in 2017, excess tax benefits from share-based award activity are reflected in the provision for income taxes.
Tax Effects of Temporary Differences and Related Deferred Tax Assets and Liabilities	The tax effects of temporary differences and related deferred tax assets and liabilities are as follows (in thousands): Balance at December 31, 2017 2016 2015 Deferred tax assets: Capitalized costs $ 35,608 $ 61,897 $ 67,051 Accrued expenses 23,553 29,421 27,964 Net operating loss carryforwards 244,197 65,507 36,633 Tax credit carryforwards 60,567 38,927 25,349 Property, equipment and intangible assets 7,390 5,721 — Share-based compensation 35,728 52,091 36,689 Other 2,519 1,640 1,469 Total deferred tax assets 409,562 255,204 195,155 Valuation allowance (409,043 ) (254,898 ) (195,103 ) Total deferred tax assets, net of valuation allowance 519 306 52 Deferred tax liabilities: Property, equipment and intangible assets (644 ) (476 ) (163 ) Total deferred tax liabilities (644 ) (476 ) (163 ) Net deferred tax liabilities $ (125 ) $ (170 ) $ (111 )
Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefit	A reconciliation of the beginning and ending amount of unrecognized tax benefit is presented below (in thousands): Year Ended December 31, 2017 2016 2015 Balance at the beginning of the year $ 92,134 $ 90,372 $ 78,031 Gross increases and decreases related to prior period tax positions — 5,190 — Gross increases and decreases related to current period tax positions 4,193 (3,428 ) 12,341 Reductions related to lapse of statute of limitations (91 ) — — Gross increases and decreases related to U.S. tax reform (25,437 ) — — Balance at the end of the year $ 70,799 $ 92,134 $ 90,372

STOCKHOLDER'S EQUITY (Tables)

STOCKHOLDER'S EQUITY (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Summary of Stock Option Activity	A summary of stock option activity for the year ended December 31, 2017 is as follows (in thousands, except share and per share data): Number of stock options outstanding Weighted Weighted Aggregate Balance at December 31, 2016 73,261,562 $ 7.70 7.28 $ 443,711 Granted 1,216,959 17.2 Exercised (24,510,745 ) 5.91 Forfeited and canceled (2,697,685 ) 11.36 Balance at December 31, 2017 47,270,091 $ 8.67 6.52 $ 1,229,103 Options vested and expected to vest at December 31, 2017 47,270,091 $ 8.67 6.52 $ 1,229,103 Options exercisable at December 31, 2017 44,252,865 $ 8.37 6.38 $ 1,163,690
Summary of RSU Activity	Activity related to RSUs during the year ended December 31, 2017 is set forth below: Number of Weighted Unvested at December 31, 2016 15,443,391 $ 12.09 Granted 14,256,257 21.21 Vested (5,964,153 ) 12.83 Forfeited (2,417,970 ) 13.29 Unvested at December 31, 2017 21,317,525 $ 17.84
Schedule of Fair Value Assumptions for Options	The fair value of stock options was estimated using the following weighted-average assumptions: Year Ended December 31, 2017 2016 2015 Dividend yield — % — % — % Risk-free interest rate 1.88 % 1.54 % 1.73 % Expected volatility 32.22 % 42.74 % 47.68 % Expected term (years) 6.02 6.08 6.02
Summary of the Effect of Share-Based Compensation on the Consolidated Statements of Operations	The following table summarizes the effects of share-based compensation on the Company's consolidated statements of operations (in thousands): Year Ended December 31, 2017 2016 2015 Cost of revenue $ 77 $ — $ — Product development 98,310 91,404 54,738 Sales and marketing 17,568 14,122 7,360 General and administrative 39,881 33,260 20,194 Total $ 155,836 $ 138,786 $ 82,292

NET LOSS PER SHARE (Tables)

NET LOSS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share	The following table presents the calculation of basic and diluted net loss per share (in thousands, except per share data): Year Ended December 31, 2017 2016 2015 Net loss $ (62,813 ) $ (171,590 ) $ (179,817 ) Deemed dividend on Series E preferred stock — — (32,200 ) Net loss attributable to common stockholders $ (62,813 ) $ (171,590 ) $ (212,017 ) Basic shares: Weighted-average common shares outstanding 380,921 344,393 175,139 Weighted-average unvested shares (1,577 ) (2,838 ) (4,641 ) Weighted-average shares used to compute basic net loss per share 379,344 341,555 170,498 Diluted shares: Weighted-average shares used to compute diluted net loss per share 379,344 341,555 170,498 Loss per share attributable to common stockholders: Basic $ (0.17 ) $ (0.50 ) $ (1.24 ) Diluted $ (0.17 ) $ (0.50 ) $ (1.24 )
Schedule of Antidilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The following potential common shares were excluded from the calculation of diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented (in thousands): Year Ended December 31, 2017 2016 2015 Stock options and restricted stock units 68,588 88,705 111,148 Common stock warrants 19,173 9,457 9,544 Unvested shares 1,300 1,892 3,420 Employee stock purchase plan 157 216 172 Total anti-dilutive securities 89,218 100,270 124,284

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Lease Payments Under Operating and Capital Leases	Future minimum lease payments under non-cancelable operating leases (with initial lease terms in excess of one year) and future minimum capital lease payments as of December 31, 2017 are as follows (in thousands): Capital Operating Year: 2018 $ 2,656 $ 18,740 2019 2,540 17,438 2020 1,265 17,374 2021 35 16,968 2022 — 16,987 Thereafter — 19,383 Total $ 6,496 $ 106,890 Less amount representing interest (14 ) Present value of capital lease obligations 6,482 Less current portion of capital lease obligation (2,650 ) Non-current portion of capital lease obligation $ 3,832

SEGMENT AND GEOGRAPHICAL INFO38

SEGMENT AND GEOGRAPHICAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Revenue by Geographic Area	Revenue by geography is based on the billing addresses of the merchants. The following table sets forth revenue by geographic area (in thousands): Year Ended December 31, 2017 2016 2015 Revenue United States $ 2,120,088 $ 1,643,852 $ 1,224,566 International 94,165 64,869 42,552 Total net revenue $ 2,214,253 $ 1,708,721 $ 1,267,118
Long-Lived Assets by Geographic Area	The following table sets forth long-lived assets by geographic area (in thousands): December 31, 2017 2016 Long-lived assets United States $ 158,820 $ 162,118 International 5,337 2,675 Total long-lived assets $ 164,157 $ 164,793

SUPPLEMENTAL CASH FLOW INFORM39

SUPPLEMENTAL CASH FLOW INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosures of Cash Flow Information	The supplemental disclosures of cash flow information consist of the following (in thousands): Year Ended December 31, 2017 2016 2015 Supplemental Cash Flow Data: Cash paid for interest $ 1,374 $ 570 $ 981 Cash paid for income taxes 1,254 395 1,916 Supplemental disclosures of non-cash investing and financing activities: Change in purchases of property and equipment in accounts payable and accrued expenses 143 2,554 5,593 Unpaid business acquisition purchase price 2,115 240 — Conversion of Series A, B, C, D & E preferred stock upon initial public offering to common stock — — 544,897 Unpaid offering costs related to initial public offering — — 5,530 Deemed dividend on Series E preferred stock — — 32,200 Fair value of shares issued related to acquisitions — — 35,776

DESCRIPTION OF BUSINESS AND S40

DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	Jun. 08, 2016USD ($)	Dec. 31, 2017USD ($)customerthird_party_processor	Dec. 31, 2016USD ($)customerthird_party_processor	Dec. 31, 2015USD ($)customer	Jan. 01, 2017USD ($)
Concentration Risk [Line Items]
Net decrease in cash, cash equivalents and restricted cash		$ (246,336,000)	$ 807,000	$ (240,893,000)
Net cash used in investing activities		(340,611,000)	(114,241,000)	(43,218,000)
Settlement agreement amount	$ 50,000,000
Payment for settlement agreement	$ 48,000,000
Advertising costs		81,900,000	58,300,000	58,300,000
Pledged cash		28,805,000	22,131,000
Collateral		9,802,000	14,584,000
Capitalized internally developed software		9,800,000	7,900,000	4,500,000
Amortization expense related to capitalized internally developed software		6,600,000	7,100,000	3,200,000
Asset retirement obligation		3,600,000
Asset retirement obligation, associated asset net of depreciation		$ 91,496,000	88,328,000
Measurement period for business combinations		1 year
Impairment charges		$ 0	$ 0	$ 0
Settlement period for customers payable		1 day
Adjustment to increase accumulated deficit and additional paid-in capital					$ 0
Leasehold Improvements Under Asset Retirement Obligation
Concentration Risk [Line Items]
Asset retirement obligation, associated asset net of depreciation		$ 2,300,000
Customer Concentration Risk | Net Revenue
Concentration Risk [Line Items]
Number of customers | customer		0	0	1
Credit Concentration Risk | Settlements Receivable
Concentration Risk [Line Items]
Number of third party processors | third_party_processor		3	3
Third Party Processor One | Credit Concentration Risk | Settlements Receivable
Concentration Risk [Line Items]
Concentration risk, percentage		46.00%	52.00%
Third Party Processor Two | Credit Concentration Risk | Settlements Receivable
Concentration Risk [Line Items]
Concentration risk, percentage		42.00%	35.00%
Third Party Processor Three | Credit Concentration Risk | Settlements Receivable
Concentration Risk [Line Items]
Concentration risk, percentage		8.00%	10.00%
Minimum
Concentration Risk [Line Items]
Contracts with third-party payment processors, period		2 years
Maximum
Concentration Risk [Line Items]
Contracts with third-party payment processors, period		4 years
Accounting Standards Update 2016-18
Concentration Risk [Line Items]
Net decrease in cash, cash equivalents and restricted cash			$ 8,500,000	$ 1,900,000
Net cash used in investing activities			$ 8,500,000	$ 1,900,000
Accounting Standards Update 2016-09
Concentration Risk [Line Items]
Adjustment to increase accumulated deficit and additional paid-in capital					$ 700,000

DESCRIPTION OF BUSINESS AND S41

DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2017
Capitalized software
Property, Plant and Equipment [Line Items]
Useful Life	18 months
Computer and data center equipment
Property, Plant and Equipment [Line Items]
Useful Life	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful Life	7 years

FAIR VALUE OF FINANCIAL INSTR42

FAIR VALUE OF FINANCIAL INSTRUMENTS - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 169,576	$ 59,901
Long-term investments	203,667	27,366
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	509,126	234,166
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	276,510	68,765
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	0
U.S. agency securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
U.S. agency securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	15,083	9,055
Long-term investments	20,169	3,502
U.S. agency securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
Corporate bonds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
Corporate bonds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	57,798	6,980
Long-term investments	91,413	12,914
Corporate bonds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
Commercial paper | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Commercial paper | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	17,428	17,298
Commercial paper | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Municipal securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
Municipal securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	23,700	8,028
Long-term investments	26,224	2,492
Municipal securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
U.S. government securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	55,567	18,540
Long-term investments	65,861	8,458
U.S. government securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
U.S. government securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Long-term investments	0	0
Money market funds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	387,698	207,168
Money market funds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Money market funds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Commercial paper | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Commercial paper | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	24,695	7,496
Commercial paper | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Municipal securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Municipal securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	1,000
Municipal securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 0	$ 0

FAIR VALUE OF FINANCIAL INSTR43

FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value of Convertible Senior Notes (Details) - Fair Value, Measurements, Recurring - Level 2 $ in Thousands	Dec. 31, 2017USD ($)
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	$ 358,572
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	$ 719,356

FAIR VALUE OF FINANCIAL INSTR44

FAIR VALUE OF FINANCIAL INSTRUMENTS - Summary of Loans Disclosed at Fair Value (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Carrying Value | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	$ 73,420,000	$ 42,144,000
Fair Value | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	76,070,000	42,633,000
Loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Excess amortized cost over fair value of loans charge	$ 8,000,000	$ 0	$ 0

INVESTMENTS - Short-term and L

INVESTMENTS - Short-term and Long-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 374,857
Fair Value	373,243
Short-term Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	169,877	$ 59,920
Gross Unrealized Gains	31	10
Gross Unrealized Losses	(332)	(29)
Fair Value	169,576	59,901
Short-term Securities | U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,122	9,048
Gross Unrealized Gains	0	7
Gross Unrealized Losses	(39)	0
Fair Value	15,083	9,055
Short-term Securities | Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	57,855	17,318
Gross Unrealized Gains	22	0
Gross Unrealized Losses	(79)	(20)
Fair Value	57,798	17,298
Short-term Securities | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	17,428	6,980
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	17,428	6,980
Short-term Securities | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	23,743	8,037
Gross Unrealized Gains	8	0
Gross Unrealized Losses	(51)	(9)
Fair Value	23,700	8,028
Short-term Securities | U.S. government securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	55,729	18,537
Gross Unrealized Gains	1	3
Gross Unrealized Losses	(163)	0
Fair Value	55,567	18,540
Long-term Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	204,980	27,424
Gross Unrealized Gains	59	0
Gross Unrealized Losses	(1,372)	(58)
Fair Value	203,667	27,366
Long-term Securities | U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,288	3,502
Gross Unrealized Gains	2	0
Gross Unrealized Losses	(121)	0
Fair Value	20,169	3,502
Long-term Securities | Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	91,959	12,939
Gross Unrealized Gains	25	0
Gross Unrealized Losses	(571)	(25)
Fair Value	91,413	12,914
Long-term Securities | Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	26,371	2,505
Gross Unrealized Gains	13	0
Gross Unrealized Losses	(160)	(13)
Fair Value	26,224	2,492
Long-term Securities | U.S. government securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	66,362	8,478
Gross Unrealized Gains	19	0
Gross Unrealized Losses	(520)	(20)
Fair Value	$ 65,861	$ 8,458

INVESTMENTS - Maturity of Avail

INVESTMENTS - Maturity of Available for Sale Securities (Details) $ in Thousands	Dec. 31, 2017USD ($)
Amortized Cost
Due in one year or less	$ 169,877
Due in one to five years	204,980
Amortized Cost	374,857
Fair Value
Due in one year or less	169,576
Due in one to five years	203,667
Total	$ 373,243

PROPERTY AND EQUIPMENT, NET -

PROPERTY AND EQUIPMENT, NET - Summary of Property, Equipment and Internally-Developed Software (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 192,812	$ 161,660
Less: Accumulated depreciation and amortization	(101,316)	(73,332)
Property and equipment, net	91,496	88,328
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	66,186	52,915
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	14,490	10,737
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	77,073	73,366
Capitalized software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 35,063	$ 24,642

PROPERTY AND EQUIPMENT, NET - N

PROPERTY AND EQUIPMENT, NET - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense on property and equipment	$ 29.7	$ 28.7	$ 20.1

GOODWILL (Details)

GOODWILL (Details)	12 Months Ended
	Dec. 31, 2017USD ($)reporting_unit	Dec. 31, 2016USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 58,327,000	$ 57,173,000
Number of reporting units | reporting_unit	1
Impairment of goodwill	$ 0

ACQUIRED INTANGIBLE ASSETS - S

ACQUIRED INTANGIBLE ASSETS - Schedule of Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	$ 40,762	$ 38,105
Accumulated Amortization	(26,428)	(18,813)
Net	14,334	19,292
Patents
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	1,285	1,285
Accumulated Amortization	(559)	(454)
Net	726	831
Technology Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	29,158	29,075
Accumulated Amortization	(21,329)	(14,702)
Net	7,829	14,373
Customer Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	10,319	7,745
Accumulated Amortization	(4,540)	(3,657)
Net	$ 5,779	$ 4,088

ACQUIRED INTANGIBLE ASSETS - Na

ACQUIRED INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 7.6	$ 9	$ 7.5
Weighted Average | Patents
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization periods	13 years
Weighted Average | Technology Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization periods	4 years
Weighted Average | Customer Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization periods	9 years

ACQUIRED INTANGIBLE ASSETS - Fu

ACQUIRED INTANGIBLE ASSETS - Future Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2,018	$ 6,226
2,019	3,442
2,020	1,479
2,021	846
2,022	611
Thereafter	1,730
Net	$ 14,334	$ 19,292

OTHER CONSOLIDATED BALANCE SH53

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (CURRENT) - Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Inventory, net	$ 16,777	$ 13,724
Processing costs receivable	21,083	10,049
Prepaid expenses	14,473	7,365
Accounts receivable, net	8,606	6,191
Deferred hardware costs	7,931	4,546
Deferred magstripe reader costs	2,469	3,911
Merchant cash advance receivable, net	125	4,212
Other	14,990	10,545
Total	$ 86,454	$ 60,543

OTHER CONSOLIDATED BALANCE SH54

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (CURRENT) - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued payroll	$ 9,103	$ 5,799
Accrued professional fees	5,638	5,788
Accrued advertising and other marketing	6,723	5,008
Processing costs payable	10,145	10,871
Accrued non income tax liabilities	6,155	3,562
Accrued hardware costs	2,496	3,148
Other accrued liabilities	12,020	5,367
Total	$ 52,280	$ 39,543

OTHER CONSOLIDATED BALANCE SH55

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (CURRENT) - Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Square Capital payable	$ 7,671	$ 4,907
Square Payroll payable	2,850	4,769
Deferred revenue	5,893	5,407
Current portion of deferred rent	3,311	2,862
Accrued redemptions	1,036	1,628
Other	7,606	2,899
Total	$ 28,367	$ 22,472

OTHER CONSOLIDATED BALANCE SH56

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (NON-CURRENT) - Other Non-Current Assets (Details) - USD ($) $ in Thousands	1 Months Ended
	Aug. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Other Non-Current Assets [Line Items]
Investment in privately held entity		$ 25,000	$ 0
Deposits		2,738	1,775
Debt issuance costs		788	1,063
Deferred tax assets		519	306
Other		2,305	50
Total		$ 31,350	$ 3,194
Eventbrite
Other Non-Current Assets [Line Items]
Initial investment in third party	$ 25,000
Service period	5 years
Renewal period after initial service agreement period	1 year

OTHER CONSOLIDATED BALANCE SH57

OTHER CONSOLIDATED BALANCE SHEET COMPONENTS (NON-CURRENT) - Other Non-Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Statutory liabilities	$ 40,768	$ 29,497
Deferred rent	20,349	23,119
Deferred tax liabilities	644	476
Other	7,777	4,653
Total	$ 69,538	$ 57,745

INDEBTEDNESS - Revolving Credit

INDEBTEDNESS - Revolving Credit Facility, Narrative (Details) - Revolving Secured Credit Facility - Revolving Secured Credit Facility - USD ($)	1 Months Ended	12 Months Ended
	Nov. 30, 2015	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 375,000,000
Annual administrative agent fee	$ 100,000
Unused commitment fee, percent	0.15%
Remaining borrowing capacity		$ 375,000,000
Unused commitment fees		$ 600,000	$ 600,000
Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
One-Month LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
One-Month LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%

INDEBTEDNESS - Convertible Seni

INDEBTEDNESS - Convertible Senior Notes, Narrative (Details) - Convertible Debt	Mar. 06, 2017USD ($)day$ / shares	Dec. 31, 2017USD ($)$ / shares
Debt Instrument [Line Items]
Aggregate principal amount	$ 400,000,000
Over-allotment option as a percentage of principal amount	10.00%
Over-allotment amount	$ 40,000,000
Interest rate	0.375%	0.375%
Conversion rate	0.0435749
Conversion price (in USD per share) | $ / shares	$ 22.95	$ 22.95
Conversion amount	$ 1,000
Carrying amount of equity component	86,200,000	$ 83,901,000
Effective interest rate of the liability component		5.34%
Discounts and commissions payable	11,000,000
Third party offering costs	800,000
Issuance costs attributable to the liability component	$ 9,400,000	$ 8,044,000
Debt Instrument, Conversion Term One
Debt Instrument [Line Items]
Threshold trading days | day	20
Threshold consecutive trading days | day	30
Threshold percentage of stock price trigger	130.00%
Debt Instrument, Conversion Term Two
Debt Instrument [Line Items]
Threshold trading days | day	5
Threshold consecutive trading days | day	5
Threshold percentage of stock price trigger	98.00%

INDEBTEDNESS - Components of Co

INDEBTEDNESS - Components of Convertible Notes (Details) - Convertible Debt - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 06, 2017
Debt Instrument [Line Items]
Principal	$ 440,000
Less: unamortized debt discount	(73,384)
Less: unamortized debt issuance costs	(8,044)	$ (9,400)
Net carrying amount	$ 358,572

INDEBTEDNESS - Carrying Amount

INDEBTEDNESS - Carrying Amount of Equity Component of Convertible Notes (Details) - Convertible Debt - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 06, 2017
Debt Instrument [Line Items]
Debt discount related to value of conversion option	$ 86,203
Less: allocated debt issuance costs	(2,302)
Equity component, net	$ 83,901	$ 86,200

INDEBTEDNESS - Interest Expense

INDEBTEDNESS - Interest Expense (Details) - Convertible Debt - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Mar. 06, 2017
Debt Instrument [Line Items]
Contractual interest expense based on 0.375% per annum	$ 1,351
Amortization of debt discount and issuance costs	14,223
Total	$ 15,574
Effective interest rate of the liability component	5.34%
Interest rate	0.375%	0.375%

INDEBTEDNESS - Convertible Bond

INDEBTEDNESS - Convertible Bond Hedge and Warrant Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 06, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 07, 2012
Debt Instrument [Line Items]
Proceeds from issuance of warrants		$ 57,244	$ 0	$ 0
Convertible Debt
Debt Instrument [Line Items]
Conversion price of convertible debt (in USD per share)	$ 22.95	$ 22.95
Conversion price of convertible debt after effect of warrants and note hedge (in USD per share)	$ 31.18
Common Stock Warrants
Debt Instrument [Line Items]
Warrants to purchase aggregate shares of capital stock (in shares)	19,200,000	19,172,956			15,761,575
Warrants, weighted average exercise price (in USD per share)	$ 31.18
Proceeds from issuance of warrants	$ 57,200
Options
Debt Instrument [Line Items]
Convertible note hedge, option to purchase common stock, price (in USD per share)	$ 22.95
Cost of convertible note hedge	$ 92,100

ACCRUED TRANSACTION LOSSES - S

ACCRUED TRANSACTION LOSSES - Summary of Reserve for Transaction Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loss Contingency Accrual [Roll Forward]
Accrued transaction losses, beginning of the year	$ 20,064
Provision for transaction losses	67,018	$ 51,235	$ 54,009
Accrued transaction losses, end of the year	26,893	20,064
Transaction Losses
Loss Contingency Accrual [Roll Forward]
Accrued transaction losses, beginning of the year	20,064	17,176	8,452
Provision for transaction losses	52,977	50,819	43,379
Charge-offs to accrued transaction losses	(46,148)	(47,931)	(34,655)
Accrued transaction losses, end of the year	$ 26,893	$ 20,064	$ 17,176

INCOME TAXES - Domestic and Fo

INCOME TAXES - Domestic and Foreign Components of Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ (10,900)	$ (145,499)	$ (157,229)
Foreign	(51,764)	(24,174)	(18,842)
Loss before income tax	$ (62,664)	$ (169,673)	$ (176,071)

INCOME TAXES - Components of Pr

INCOME TAXES - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ (1,192)	$ 63	$ 1,662
State	739	527	836
Foreign	1,987	1,269	1,222
Total current provision for income taxes	1,534	1,859	3,720
Deferred:
Federal	(1,169)	173	67
State	57	18	11
Foreign	(273)	(133)	(52)
Total deferred provision for income taxes	(1,385)	58	26
Total provision for income taxes	$ 149	$ 1,917	$ 3,746

INCOME TAXES - Reconciliation o

INCOME TAXES - Reconciliation of Statutory Federal Income Tax Rate to Company's Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax at federal statutory rate	34.00%	34.00%	34.00%
State taxes, net of federal benefit	(0.40%)	(0.10%)	(0.20%)
Foreign rate differential	(14.90%)	(2.40%)	(1.80%)
Nondeductible expenses	(1.00%)	(0.90%)	(1.10%)
Credits	41.50%	8.50%	8.20%
Other items	(1.20%)	0.20%	0.10%
Change in valuation allowance	(119.50%)	(37.40%)	(38.60%)
Impact of U.S. tax reform	(209.10%)	0.00%	0.00%
Share-based compensation	243.50%	(2.40%)	(2.20%)
Change in uncertain tax positions	(2.40%)	(0.60%)	(0.50%)
Termination of warrant	29.30%	0.00%	0.00%
Total	(0.20%)	(1.10%)	(2.10%)

INCOME TAXES - Tax Effects of T

INCOME TAXES - Tax Effects of Temporary Differences and Related Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Capitalized costs	$ 35,608	$ 61,897	$ 67,051
Accrued expenses	23,553	29,421	27,964
Net operating loss carryforwards	244,197	65,507	36,633
Tax credit carryforwards	60,567	38,927	25,349
Property, equipment and intangible assets	7,390	5,721	0
Share-based compensation	35,728	52,091	36,689
Other	2,519	1,640	1,469
Total deferred tax assets	409,562	255,204	195,155
Valuation allowance	(409,043)	(254,898)	(195,103)
Total deferred tax assets, net of valuation allowance	519	306	52
Deferred tax liabilities:
Property, equipment and intangible assets	(644)	(476)	(163)
Total deferred tax liabilities	(644)	(476)	(163)
Net deferred tax liabilities	$ (125)	$ (170)	$ (111)

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Discrete net tax benefit due to Tax Act	$ 1,300
Decrease in U.S. Federal and state DTAs due to Tax Act	63,600
Decrease in valuation allowance due to Tax Act	63,600
Increase in valuation allowance	154,100	$ 59,800	$ 69,700
Unrecognized tax benefits	70,799	$ 92,134	$ 90,372	$ 78,031
Unrecognized tax benefit that would impact annual effective tax rate	4,500
Significant accrued interest and penalties related to uncertain tax positions	0
Undistributed earnings of non-U.S. subsidiaries	4,100
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	774,200
Federal | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	42,600
Federal | AMT Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	1,300
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	594,200
State | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	31,100
State | California Enterprise Zone Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	2,800
Foreign
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	131,700
Foreign | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	1,600
Maximum | Tax examinations or lapse of applicable statute of limitations
Operating Loss Carryforwards [Line Items]
Reasonably possible decrease in unrecognized tax benefits	$ 13,000

INCOME TAXES - Reconciliation70

INCOME TAXES - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 92,134	$ 90,372	$ 78,031
Gross increases and decreases related to prior period tax positions	0	5,190	0
Gross increases related to current period tax positions	4,193		12,341
Gross decreases related to current period tax positions		(3,428)
Reductions related to lapse of statute of limitations	(91)	0	0
Gross increases and decreases related to U.S. tax reform	(25,437)	0	0
Balance at the end of the year	$ 70,799	$ 92,134	$ 90,372

STOCKHOLDER'S EQUITY - Common S

STOCKHOLDER'S EQUITY - Common Stock and Warrants Narrative (Details) $ / shares in Units, $ in Thousands	Mar. 06, 2017USD ($)$ / sharesshares	Feb. 24, 2017USD ($)shares	Nov. 24, 2015USD ($)shares	Nov. 30, 2015USD ($)$ / sharesshares	Dec. 31, 2017USD ($)vote$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)shares	Aug. 07, 2012shares
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)					100,000,000	100,000,000
Preferred stock, par value (in USD per share) | $ / shares					$ 0.00	$ 0.00
Preferred stock, shares outstanding (in shares)					0	0
Series E preferred stock issued (in shares)							10,299,696
Deemed dividend on Series E preferred stock | $							$ 0
Consideration paid for termination of warrants | $					$ 54,808	$ 0	0
Proceeds from issuance of warrants | $					$ 57,244	$ 0	$ 0
Common Stock Warrants
Class of Stock [Line Items]
Warrants to purchase shares of common, canceled (in shares)		9,500,000					6,304,620
Consideration paid for termination of warrants | $		$ 54,800
Outstanding warrants to purchase aggregate shares of capital stock (in shares)	19,200,000				19,172,956			15,761,575
Exercise price of warrants (in USD per share) | $ / shares	$ 31.18
Proceeds from issuance of warrants | $	$ 57,200
Weighted Average | Common Stock Warrants
Class of Stock [Line Items]
Exercise price of warrants (in USD per share) | $ / shares					$ 31.18
Class A Common Stock
Class of Stock [Line Items]
Number of votes per share | vote					1
Common stock, shares authorized (in shares)					1,000,000,000	1,000,000,000
Common stock, par value (in USD per share) | $ / shares					$ 0.00	$ 0.00
Common stock, shares outstanding (in shares)					280,400,813	198,746,620
Class B Common Stock
Class of Stock [Line Items]
Number of votes per share | vote					10
Common stock, shares authorized (in shares)					500,000,000	500,000,000
Common stock, par value (in USD per share) | $ / shares					$ 0.00	$ 0.00
Common stock, shares outstanding (in shares)					114,793,262	165,800,756
Common Stock
Class of Stock [Line Items]
Series E preferred stock issued (in shares)			10,299,696				10,299,696
Net Loss to Arrive at Net Loss Attributable to Common Stockholders
Class of Stock [Line Items]
Deemed dividend on Series E preferred stock | $			$ 32,200				$ (32,200)
IPO
Class of Stock [Line Items]
Net proceeds received from the IPO | $							$ 245,726
IPO | Class A Common Stock
Class of Stock [Line Items]
Issuance of stock (in shares)				29,700,000
Public offering price (in USD per share) | $ / shares				$ 9
Net proceeds received from the IPO | $				$ 245,700
Underwriting discounts and commissions | $				14,700
Other offering expenses | $				$ 6,900
IPO | Common Stock
Class of Stock [Line Items]
Issuance of stock (in shares)							29,700,000

STOCKHOLDER'S EQUITY - Share-Ba

STOCKHOLDER'S EQUITY - Share-Based Compensation Narrative (Details)	Aug. 31, 2015	Jan. 31, 2015shares	Dec. 31, 2017USD ($)planpayment_plan$ / sharesshares	Dec. 31, 2016USD ($)$ / shares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2017USD ($)shares	Nov. 17, 2015shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans | plan			2
Aggregate intrinsic value for options exercised | $			$ 464,100,000	$ 202,600,000	$ 49,800,000
Weighted average grant-date fair value of options granted (in USD per share) | $ / shares			$ 5.97	$ 5.80	$ 5.87
Share-based compensation expense | $			$ 155,836,000	$ 138,786,000	$ 82,292,000
Share-based compensation expense related to capitalized software | $			3,700,000	2,800,000	$ 0
Unrecognized compensation cost related to outstanding stock options and restricted stock awards | $			$ 423,800,000			$ 423,800,000
Unrecognized compensation cost related to outstanding stock options and restricted stock awards, recognition period			2 years 9 months 18 days
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share contributed for consideration and retired (in shares)		5,068,238			5,068,238
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Required service period	2 years
Plan modification, incremental share-based compensation cost | $			$ 1,900,000	2,600,000	$ 3,300,000
Plan modification, incremental share-based compensation cost not yet recognized | $			$ 1,900,000			$ 1,900,000
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term			4 years
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $			$ 6,000,000	$ 5,100,000
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved (in shares)							30,000,000
Shares reserved for issuance, percent			5.00%
Number of shares available for future issuance (in shares)			45,785,515			45,785,515
2015 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase of number of shares reserved (in shares)			40,000,000			40,000,000
2015 Equity Incentive Plan | Options and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options and RSU outstanding (in shares)			25,971,958			25,971,958
2009 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance (in shares)							0
2009 Stock Option Plan | Options and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options and RSU outstanding (in shares)			42,615,658			42,615,658
2009 Stock Option Plan | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term			4 years
Expiration period			10 years
2009 Stock Option Plan | Options | Vesting Year One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting rate			25.00%
2015 Employee Stock Purchase Plan | Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance, percent			1.00%
Number of shares available for future issuance (in shares)			7,672,022			7,672,022
Discount through payroll deductions as a percentage of eligible compensation			15.00%
Offering period			12 months
Number of purchase periods | payment_plan			2
Purchase price of common stock as a percentage of fair market value			85.00%
Shares purchased under the plan (in shares)						3,522,945
2015 Employee Stock Purchase Plan | Employee Stock Purchase Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase of number of shares reserved (in shares)			8,400,000			8,400,000

STOCKHOLDER'S EQUITY - Summary

STOCKHOLDER'S EQUITY - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Number of stock options outstanding
Beginning balance (in shares)	73,261,562
Granted (in shares)	1,216,959
Exercised (in shares)	(24,510,745)
Forfeited and canceled (in shares)	(2,697,685)
Ending balance (in shares)	47,270,091	73,261,562
Weighted average exercise price
Beginning balance (in USD per share)	$ 7.70
Granted (in USD per share)	17.20
Exercised (in USD per share)	5.91
Forfeited and canceled (in USD per share)	11.36
Ending balance (in USD per share)	$ 8.67	$ 7.70
Options Vested and Expected to Vest
Number of stock options outstanding (in shares)	47,270,091
Weighted average exercise price (in USD per share)	$ 8.67
Weighted average remaining contractual term (in years)	6 years 6 months 7 days
Aggregate intrinsic value	$ 1,229,103
Additional Disclosures
Weighted average remaining contractual term (in years)	6 years 6 months 7 days	7 years 3 months 11 days
Aggregate intrinsic value	$ 1,229,103	$ 443,711
Options exercisable, number of stock options outstanding (in shares)	44,252,865
Options exercisable, weighted average exercise price (in USD per share)	$ 8.37
Options exercisable, weighted average remaining contractual term (in years)	6 years 4 months 17 days
Options exercisable, aggregate intrinsic value	$ 1,163,690

STOCKHOLDER'S EQUITY - RSU Acti

STOCKHOLDER'S EQUITY - RSU Activity (Details) - RSUs	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Number of RSUs
Beginning balance (in shares) | shares	15,443,391
Granted (in shares) | shares	14,256,257
Vested (in shares) | shares	(5,964,153)
Forfeited (in shares) | shares	(2,417,970)
Ending balance (in shares) | shares	21,317,525
Weighted average grant date fair value
Beginning balance (in USD per share) | $ / shares	$ 12.09
Granted (in USD per share) | $ / shares	21.21
Vested (in USD per share) | $ / shares	12.83
Forfeited (in USD per share) | $ / shares	13.29
Ending balance (in USD per share) | $ / shares	$ 17.84

STOCKHOLDER'S EQUITY - Stock Op

STOCKHOLDER'S EQUITY - Stock Options Fair Value Assumptions (Details) - Options	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate	1.88%	1.54%	1.73%
Expected volatility	32.22%	42.74%	47.68%
Expected term (years)	6 years 7 days	6 years 29 days	6 years 7 days

STOCKHOLDER'S EQUITY - Effects

STOCKHOLDER'S EQUITY - Effects of Share-Based Compensation on Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 155,836	$ 138,786	$ 82,292
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	77	0	0
Product development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	98,310	91,404	54,738
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	17,568	14,122	7,360
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 39,881	$ 33,260	$ 20,194

NET LOSS PER SHARE - Calculati

NET LOSS PER SHARE - Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Deemed dividend on Series E preferred stock (in shares)			10,299,696
Net loss	$ (62,813)	$ (171,590)	$ (179,817)
Deemed dividend on Series E preferred stock	0	0	(32,200)
Net loss attributable to common stockholders	$ (62,813)	$ (171,590)	$ (212,017)
Basic shares:
Weighted-average common shares outstanding (in shares)	380,921,000	344,393,000	175,139,000
Weighted-average unvested shares (in shares)	(1,577,000)	(2,838,000)	(4,641,000)
Weighted-average shares used to compute basic net loss per share (in shares)	379,344,000	341,555,000	170,498,000
Diluted shares:
Weighted-average shares used to compute diluted net loss per share (in shares)	379,344,000	341,555,000	170,498,000
Loss per share attributable to common stockholders:
Basic (in USD per share)	$ (0.17)	$ (0.50)	$ (1.24)
Diluted (in USD per share)	$ (0.17)	$ (0.50)	$ (1.24)

NET LOSS PER SHARE - Antidiluti

NET LOSS PER SHARE - Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 06, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	89,218	100,270	124,284
Stock options and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	68,588	88,705	111,148
Unvested shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,300	1,892	3,420
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	157	216	172
Common stock warrants | Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	19,173	9,457	9,544
Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion price of convertible debt (in USD per share)	$ 22.95			$ 22.95

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Rental expenses under operating leases	$ 12.9	$ 11.3	$ 12.8

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Lease Payments Under Operating and Capital Leases (Details) $ in Thousands	Dec. 31, 2017USD ($)
Capital
2,018	$ 2,656
2,019	2,540
2,020	1,265
2,021	35
2,022	0
Thereafter	0
Total	6,496
Less amount representing interest	(14)
Present value of capital lease obligations	6,482
Less current portion of capital lease obligation	(2,650)
Non-current portion of capital lease obligation	3,832
Operating
2,018	18,740
2,019	17,438
2,020	17,374
2,021	16,968
2,022	16,987
Thereafter	19,383
Total	$ 106,890

SEGMENT AND GEOGRAPHICAL INFO81

SEGMENT AND GEOGRAPHICAL INFORMATION - Narrative (Details)	12 Months Ended
	Dec. 31, 2017segment
Segment Reporting [Abstract]
Number of operating segments	1
Number of reportable segments	1

SEGMENT AND GEOGRAPHICAL INFO82

SEGMENT AND GEOGRAPHICAL INFORMATION - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 2,214,253	$ 1,708,721	$ 1,267,118
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	2,120,088	1,643,852	1,224,566
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 94,165	$ 64,869	$ 42,552

SEGMENT AND GEOGRAPHICAL INFO83

SEGMENT AND GEOGRAPHICAL INFORMATION - Long-Lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 164,157	$ 164,793
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	158,820	162,118
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 5,337	$ 2,675

SUPPLEMENTAL CASH FLOW INFORM84

SUPPLEMENTAL CASH FLOW INFORMATION - Supplemental Disclosures of Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Data:
Cash paid for interest	$ 1,374	$ 570	$ 981
Cash paid for income taxes	1,254	395	1,916
Supplemental disclosures of non-cash investing and financing activities:
Change in purchases of property and equipment in accounts payable and accrued expenses	143	2,554	5,593
Unpaid business acquisition purchase price	2,115	240	0
Conversion of Series A, B, C, D & E preferred stock upon initial public offering to common stock	0	0	544,897
Unpaid offering costs related to initial public offering	0	0	5,530
Deemed dividend on Series E preferred stock	0	0	32,200
Fair value of shares issued related to acquisitions	$ 0	$ 0	$ 35,776

Uncategorized Items - sq-201712

Label	Element	Value
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (683,000)
Additional Paid-in Capital [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 683,000