Redfin (RDFN) 10-Q 6 Nov 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-38160
Entity Registrant Name	Redfin Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	74-3064240
Entity Address, Address Line One	1099 Stewart Street
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98101
City Area Code	(206)
Local Phone Number	576-8333
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	RDFN
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		92,261,363
Entity Central Index Key	0001382821
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 209,234,000	$ 432,608,000
Restricted cash	9,984,000	6,446,000
Short-term investments	62,054,000	0
Accrued revenue, net	24,434,000	15,363,000
Inventory	105,460,000	22,694,000
Loans held for sale	22,246,000	4,913,000
Prepaid expenses	8,391,000	11,916,000
Other current assets	5,763,000	2,307,000
Total current assets	447,566,000	496,247,000
Property and equipment, net	37,560,000	25,187,000
Right-of-use assets, net	45,513,000
Long-term investments	38,480,000	0
Goodwill and intangibles, net	11,626,000	11,992,000
Other non-current assets	11,240,000	9,395,000
Total assets	591,985,000	542,821,000
Current liabilities
Accounts payable	3,173,000	2,516,000
Accrued liabilities	50,867,000	30,837,000
Other payables	7,157,000	6,544,000
Borrowings under warehouse credit facilities	21,987,000	4,733,000
Current operating lease liabilities	9,731,000
Current portion of deferred rent	132,000	1,588,000
Total current liabilities	93,047,000	46,218,000
Non-current operating lease liabilities	53,059,000
Deferred rent	0	11,079,000
Convertible senior notes, net	118,158,000	113,586,000
Total liabilities	264,264,000	170,883,000
Commitments and contingencies (Note 7)
Stockholders’ equity
Common stock—par value $0.001 per share; 500,000,000 shares authorized; 92,212,316 and 90,151,341 shares issued and outstanding, respectively	92,000	90,000
Additional paid-in capital	571,607,000	542,829,000
Accumulated other comprehensive income	26,000	0
Accumulated deficit	(244,004,000)	(170,981,000)
Total stockholders’ equity	327,721,000	371,938,000
Total liabilities and stockholders’ equity	$ 591,985,000	$ 542,821,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	500,000,000	500,000,000
Common stock, issued (in shares)	92,212,316	90,151,341
Common stock, outstanding (in shares)	92,212,316	90,151,341

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue	$ 238,683	$ 140,255	$ 546,605	$ 362,791
Cost of revenue	185,306	97,950	442,127	269,576
Gross profit	53,377	42,305	104,478	93,215
Operating expenses
Technology and development	18,801	14,310	50,421	40,105
Marketing	8,361	8,236	68,611	36,006
General and administrative	18,779	16,470	57,881	48,532
Total operating expenses	45,941	39,016	176,913	124,643
Income (loss) from operations	7,436	3,289	(72,435)	(31,428)
Interest income	1,576	1,775	5,804	3,082
Interest expense	(2,274)	(1,610)	(6,564)	(1,610)
Other income, net	44	21	172	200
Net income (loss)	$ 6,782	$ 3,475	$ (73,023)	$ (29,756)
Net income (loss) per share - basic (in dollars per share)	$ 0.07	$ 0.04	$ (0.80)	$ (0.35)
Net income (loss) per share - diluted (in dollars per share)	$ 0.07	$ 0.04	$ (0.80)	$ (0.35)
Weighted average shares - basic (in shares)	91,994,731	87,743,223	91,279,086	84,327,266
Weighted average shares - diluted (in shares)	97,171,270	94,642,463	91,279,086	84,327,266
Foreign currency translation adjustments	$ (10)	$ 0	$ 28	$ 0
Unrealized loss on available-for-sale securities	(8)	0	(2)	0
Total comprehensive loss	6,764	3,475	(72,997)	(29,756)
Service
Revenue	158,519	128,905	405,160	339,403
Cost of revenue	104,397	86,294	297,320	245,490
Product
Revenue	80,164	11,350	141,445	23,388
Cost of revenue	$ 80,909	$ 11,656	$ 144,807	$ 24,086

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net loss	$ (73,023)	$ (29,756)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,366	6,123
Stock-based compensation	19,792	14,472
Amortization of debt discount and issuance costs	4,674	1,128
Non-cash lease expense	4,727	0
Other	(401)	0
Change in assets and liabilities:
Accrued revenue	(9,071)	80
Inventory	(82,766)	(21,779)
Prepaid expenses and other assets	(82)	1,808
Accounts payable	579	702
Accrued liabilities and other payables	18,994	11,357
Operating lease liabilities	(5,207)	0
Deferred rent	112	(913)
Origination of loans held for sale	(285,182)	(56,157)
Proceeds from sale of loans originated as held for sale	267,850	52,127
Net cash used in operating activities	(132,638)	(20,808)
Investing activities
Purchases of property and equipment	(12,821)	(5,528)
Purchases of investments	(106,063)	0
Sales of investments	1,005	0
Maturities of investments	4,900	0
Net cash used in investing activities	(112,979)	(5,528)
Financing activities
Proceeds from the issuance of shares resulting from employee equity plans	10,869	17,314
Tax payments related to net share settlements on restricted stock units	(2,856)	(705)
Borrowings from warehouse credit facilities	280,129	54,806
Repayments of warehouse credit facilities	(262,875)	(51,031)
Other payables - deposits held in escrow	637	7,684
Proceeds from issuance of convertible notes, net of issuance costs	0	138,953
Proceeds from follow on offering	0	107,593
Cash paid for debt issuance costs	(152)	0
Net cash provided by financing activities	25,752	274,614
Effect of exchange rate changes on cash and cash equivalents	28	0
Net change in cash, cash equivalents, and restricted cash	(219,837)	248,278
Cash, cash equivalents, and restricted cash:
Beginning of period	439,055	212,658
End of period	219,218	460,936
Supplemental disclosure of cash flow information
Cash paid for interest	2,460	0
Non-cash transactions
Stock-based compensation capitalized in property and equipment	(931)	(363)
Property and equipment additions in accounts payable and accrued liabilities	(404)	(25)
Leasehold improvements paid directly by lessor	$ (4,298)	$ (926)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance (in shares) at Dec. 31, 2017		81,468,891
Beginning balance at Dec. 31, 2017	$ 235,430	$ 81	$ 364,352	$ (129,003)	$ 0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock pursuant to employee stock purchase program (in shares)		187,076
Issuance of common stock pursuant to employee stock purchase program	3,672		3,672
Issuance of common stock pursuant to exercise of stock options (in shares)		2,653,008
Issuance of common stock pursuant to exercise of stock options	13,728	$ 3	13,725
Issuance of common stock pursuant to settlement of restricted stock units (in shares)		127,746
Issuance of common stock pursuant to settlement of restricted stock units	0
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)		(38,238)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(705)		(705)
Stock-based compensation	14,835		14,835
Equity component of convertible senior notes, net	27,951		27,951
Net loss	(29,756)			(29,756)
Ending balance (in shares) at Sep. 30, 2018		89,234,819
Ending balance at Sep. 30, 2018	372,748	$ 89	531,418	(158,759)	0
Increase (Decrease) in Stockholders' Equity
Stock Issued During Period, Shares, New Issues		4,836,336
Stock Issued During Period, Value, New Issues	107,593	$ 5	107,588
Beginning balance (in shares) at Jun. 30, 2018		83,785,251
Beginning balance at Jun. 30, 2018	225,613	$ 84	387,764	(162,235)	0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock pursuant to exercise of stock options (in shares)		544,523
Issuance of common stock pursuant to exercise of stock options	2,976		2,976
Issuance of common stock pursuant to settlement of restricted stock units (in shares)		96,724
Issuance of common stock pursuant to settlement of restricted stock units	0
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)		(28,015)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(478)		(478)
Stock-based compensation	5,617		5,617
Equity component of convertible senior notes, net	27,951		27,951
Net loss	3,475			3,475
Ending balance (in shares) at Sep. 30, 2018		89,234,819
Ending balance at Sep. 30, 2018	$ 372,748	$ 89	531,418	(158,759)	0
Increase (Decrease) in Stockholders' Equity
Stock Issued During Period, Shares, New Issues	4,836,336
Stock Issued During Period, Value, New Issues	$ 107,593	$ 5	107,588
Beginning balance (in shares) at Dec. 31, 2018	90,151,341	90,151,341
Beginning balance at Dec. 31, 2018	$ 371,938	$ 90	542,829	(170,981)	0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock pursuant to employee stock purchase program (in shares)		262,110
Issuance of common stock pursuant to employee stock purchase program	$ 3,246		3,246
Issuance of common stock pursuant to exercise of stock options (in shares)	1,397,074	1,397,074
Issuance of common stock pursuant to exercise of stock options	$ 7,667	$ 2	7,665
Issuance of common stock pursuant to settlement of restricted stock units (in shares)		562,755
Issuance of common stock pursuant to settlement of restricted stock units	0
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)		(160,964)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(2,856)		(2,856)
Stock-based compensation	20,723		20,723
Other comprehensive income (loss)	26				26
Net loss	$ (73,023)			(73,023)
Ending balance (in shares) at Sep. 30, 2019	92,212,316	92,212,316
Ending balance at Sep. 30, 2019	$ 327,721	$ 92	571,607	(244,004)	26
Beginning balance (in shares) at Jun. 30, 2019		91,777,537
Beginning balance at Jun. 30, 2019	312,245	$ 92	562,894	(250,785)	44
Increase (Decrease) in Stockholders' Equity
Issuance of common stock pursuant to exercise of stock options (in shares)		297,475
Issuance of common stock pursuant to exercise of stock options	1,897		1,897
Issuance of common stock pursuant to settlement of restricted stock units (in shares)		195,840
Issuance of common stock pursuant to settlement of restricted stock units	0
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)		(58,536)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(1,064)		(1,064)
Stock-based compensation	7,880		7,880
Other comprehensive income (loss)	(18)				(18)
Net loss	$ 6,782			6,782
Ending balance (in shares) at Sep. 30, 2019	92,212,316	92,212,316
Ending balance at Sep. 30, 2019	$ 327,721	$ 92	$ 571,607	$ (244,004)	$ 26

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation —The consolidated financial statements and accompanying notes have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). All amounts are presented in thousands, except share and per share amounts. The financial information as of December 31, 2018 that is included in this Quarterly Report is derived from the audited consolidated financial statements and notes for the year ended December 31, 2018 included in Item 8 in the Annual Report on Form 10-K (the “2018 Annual Report”) of Redfin Corporation (the "Company" or "Redfin"). Such financial information should be read in conjunction with the notes and management’s discussion and analysis of the consolidated financial statements included in the 2018 Annual Report. The unaudited condensed consolidated financial statements, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly the Company's financial position as of September 30, 2019 , the statements of comprehensive income (loss) and stockholders' equity for the three and nine months ended September 30, 2019 and 2018 , and the statement of cash flows for the nine months ended September 30, 2019 and 2018. The results for the three and nine months ended September 30, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019 or for any interim period or for any other future year. Principles of Consolidation —The unaudited condensed consolidated interim financial statements include the accounts of Redfin and its wholly owned subsidiaries. Intercompany transactions and balances have been eliminated. Use of Estimates — The preparation of consolidated financial statements, in conformity with GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and results of operations during the respective periods. The Company evaluates its estimates on an ongoing basis. During the nine months ended September 30, 2019 , the estimated useful life of capitalized software for internal use was updated from one to two years . This change in estimate was not material. In addition, with the adoption of Accounting Standards Codification Topic 842, Leases , the Company estimated its incremental borrowing rate for the determination of the present value of lease payments. Further description of the impact of this pronouncement is included in Note 6. The amounts ultimately realized from the affected assets or liabilities will depend on, among other factors, general business conditions and could differ materially in the near term from the carrying amounts reflected in the consolidated financial statements. Cash and Cash Equivalents —Cash equivalents consist primarily of money market instruments and U.S. treasury securities. The Company considers all highly liquid investments originally purchased by the Company with original maturities of three months or less at the date of purchase to be cash equivalents and classified as available-for-sale. Investments —The Company has two types of investments: (i) available-for-sale investments that are available to support operational needs of the Company, which are reported on the balance sheet as short-term and long-term investments, and (ii) long-term equity investments accounted for under the cost method, which are reported in other non-current assets. Available-for-sale The Company's short-term and long-term investments consist primarily of U.S. treasury securities, all of which are classified as available-for-sale. Available-for-sale debt securities are recorded at fair value, and unrealized holding gains and losses are recorded as a component of accumulated other comprehensive income. Available-for-sale securities with maturities of one year or less and those identified by management at the time of purchase to be used to fund operations within one year are classified as short-term. All other available-for-sale securities are classified as long-term. The Company evaluates its available-for-sale securities, both ones classified as cash equivalents and as investments, for other-than-temporary impairment on a quarterly basis. Unrealized losses are charged against net earnings when a decline in fair value is determined to be other than temporary. The Company reviews factors to determine whether a loss is other than temporary, such as the length and extent of the fair value decline, the financial condition and near-term prospects of the issuer, and whether the Company has the intent to sell or will more likely than not be required to sell before the securities' anticipated recovery, which may be at maturity. Realized gains and losses are accounted for using the specific identification method. Purchases and sales are recorded on a trade date basis. There were no other than temporary impairments during the periods presented. Cost Method Investments In December 2018, the Company purchased an equity interest in a privately held company for approximately $2,000 , which is classified as long-term. The investment is an equity security without a readily determinable fair value that is accounted for at cost minus any impairment, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same issuer. The Company performs a qualitative assessment considering impairment indicators to evaluate whether the investment is impaired as of the end of each reporting period. Advertising and Advertising Production Costs —The Company expenses advertising costs as they are incurred and production costs as of the first date the advertisement takes place. Advertising costs totaled $5,279 and $5,936 for the three months ended September 30, 2019 and 2018 , respectively, and $59,357 and $29,167 for the nine months ended September 30, 2019 and 2018 , respectively, and are included in marketing expenses. Advertising production costs totaled $17 and $7 for the three months ended September 30, 2019 and 2018 , respectively, and $166 and $20 for the nine months ended September 30, 2019 and 2018 , respectively, and are included in marketing expenses. Recently Adopted Accounting Pronouncements —In January 2019, the Company adopted ASU 2016-02, Leases (Topic 842) , using the optional alternative transition method under ASU 2018-11, Leases (Topic 842) Targeted Improvements . The optional alternative transition method applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company evaluated its portfolio of leases and determined a cumulative-effect adjustment to the opening balance of retained earnings was not needed, as the portfolio of leases contains only operating leases. The Company elected the package of practical expedients permitted under the transition guidance within the standard, allowing the Company to carry forward the historical lease classification, carry forward the conclusions on whether current or expired contracts contain leases, and carry forward the accounting for initial direct costs for existing leases. Additionally, the Company elected the practical expedient for use of hindsight to determine the lease term for existing leases whereby it evaluated the performance of existing leases in relation to our leasing strategy and determined that most renewal options would not be reasonably certain to be exercised. This resulted in the shortening of lease terms for the existing leases. Adoption of the standard resulted in the recording of right of use assets and corresponding lease liabilities of $33,953 and $49,395 , respectively, as of January 1, 2019, the difference of which is due to lease incentives. Further description of the impact of this pronouncement is included in Note 6. In January 2019, the Company adopted the guidance in the U.S. Securities and Exchange Commission (the "SEC") final rule under SEC Release No. 33-10532, Disclosure Update and Simplification. In August 2018, the SEC issued the final rule amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated, or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. In August 2018, the Financial Accounting Standards Board ("FASB") issued authoritative guidance under ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract . The ASU requires implementation costs incurred by customers in cloud computing arrangements (i.e., hosting arrangements) to be capitalized under the same premises of authoritative guidance for internal-use software, and deferred over the noncancelable term of the cloud computing arrangements plus any option renewal periods that are reasonably certain to be exercised by the customer or for which the exercise is controlled by the service provider. The ASU is effective for public entities for fiscal years beginning after December 15, 2019 and early adoption is permitted. The Company elected to early adopt this standard in the third quarter of 2019 on a prospective basis, which did not result in a material effect on the Company's consolidated financial statements. Recently Issued Accounting Pronouncements — In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) , which modifies the disclosures on fair value measurements by removing the requirement to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy and the policy for timing of such transfers. The ASU expands the disclosure requirements for Level 3 fair value measurements, primarily focused on changes in unrealized gains and losses included in other comprehensive income. The ASU is effective for public entities for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company has not yet completed its assessment of the impact of the new standard on the Company’s consolidated financial statements. In June 2016, the FASB issued authoritative guidance under ASU 2016-13, Financial Instruments—Credit Losses (Topic 326), which modifies the measurement of credit losses on financial instruments. This guidance requires the use of an expected loss impairment model for instruments measured at amortized cost based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. For available-for-sale debt securities, an entity is required to recognize credit losses through an allowance for credit losses rather than as an impairment. The ASU is effective for interim and annual reporting periods beginning after December 15, 2019, and early adoption is permitted. The adoption of this guidance requires a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company completed its assessment of the impact of the new standard on the Company’s consolidated financial statements and does not expect a material impact.

Segment Reporting and Revenue

Segment Reporting and Revenue	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Reporting and Revenue	Segment Reporting and Revenue In its operation of the business, the Company's management, including its chief operating decision maker, who is also the Chief Executive Officer, evaluates the performance of the Company’s operating segments based on revenue and gross profit. The Company does not analyze discrete segment balance sheet information related to long-term assets, all of which are located in the United States. All other financial information is presented on a consolidated basis. The Company has five operating segments and two reportable segments, real estate services and properties. Revenue is primarily generated from commissions and fees charged on each real estate services transaction completed by the Company or its partner agents, and proceeds from the sales of homes. The Company’s key revenue components are brokerage revenue, partner revenue, properties revenue, and other revenue. Revenue earned but not received is recorded as accrued revenue on the Company's consolidated balance sheets, net of an allowance for doubtful accounts. Accrued revenue, consisting of commission revenue, is known and is clearing escrow, and therefore it is not estimated. Information on each of the reportable and other segments and reconciliation to consolidated net income (loss) is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Real estate services Brokerage revenue $ 146,096 $ 118,809 $ 372,809 $ 312,306 Partner revenue 8,030 7,456 20,053 19,741 Total real estate services revenue 154,126 126,265 392,862 332,047 Cost of revenue 100,048 83,274 284,447 236,775 Gross profit 54,078 42,991 108,415 95,272 Properties Revenue 80,164 11,350 141,445 23,388 Cost of revenue 80,909 11,656 144,807 24,086 Gross profit (745 ) (306 ) (3,362 ) (698 ) Other Revenue 5,161 2,691 13,490 7,407 Cost of revenue 5,117 3,071 14,065 8,766 Gross profit 44 (380 ) (575 ) (1,359 ) Intercompany eliminations Revenue (768 ) (51 ) (1,192 ) (51 ) Cost of revenue (768 ) $ (51 ) (1,192 ) (51 ) Gross profit — — — — Consolidated Revenue 238,683 140,255 546,605 362,791 Cost of revenue 185,306 97,950 442,127 269,576 Gross profit 53,377 42,305 104,478 93,215 Operating expenses 45,941 39,016 176,913 124,643 Interest income 1,576 1,775 5,804 3,082 Interest expense (2,274 ) (1,610 ) (6,564 ) (1,610 ) Other income, net 44 21 172 200 Net income (loss) $ 6,782 $ 3,475 $ (73,023 ) $ (29,756 ) The following table presents the detail of accrued revenue for the periods presented: Nine Months Ended September 30, 2019 2018 Accrued revenue $ 24,703 $ 13,411 Less: Allowance for doubtful accounts (269 ) (157 ) Accrued revenue, net $ 24,434 $ 13,254 The following table presents the activity in the allowance for doubtful accounts for the period presented: Nine Months Ended September 30, 2019 2018 Balance, beginning of period $ 166 $ 160 Charges 128 23 Write-offs (25 ) (26 ) Balance, end of period $ 269 $ 157

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments A summary of assets and liabilities as of September 30, 2019 and December 31, 2018 , related to the Company's financial instruments measured at fair value on a recurring basis, is set forth below, along with the balance sheet accounts they are classified within: Balance as of September 30, 2019 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash equivalents Money market funds $ 198,172 $ 198,172 $ — $ — U.S. treasury securities 282 — 282 — Short-term investments U.S. treasury securities 62,054 — 62,054 — Loans held for sale 22,246 — 22,246 — Prepaid expenses and other current assets Forward sales commitments 216 — 216 — Interest rate lock commitments 603 — — 603 Total prepaid expenses and other current assets 819 — 216 603 Long-term investments U.S. treasury securities 38,480 — 38,480 — Total assets $ 322,053 $ 198,172 $ 123,278 $ 603 Liabilities Accrued liabilities Forward sales commitments $ 44 $ — $ 44 $ — Interest rate lock commitments 124 — — 124 Total liabilities $ 168 $ — $ 44 $ 124 Balance as of December 31, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash equivalents Money market funds $ 425,776 $ 425,776 $ — $ — Loans held for sale 4,913 — 4,913 — Prepaid expenses and other current assets Interest rate lock commitments 254 — — 254 Total prepaid expenses and other current assets 254 — — 254 Total assets $ 430,943 $ 425,776 $ 4,913 $ 254 Liabilities Accrued liabilities Forward sales commitments $ 141 $ — $ 141 $ — Total liabilities $ 141 $ — $ 141 $ — There were no material transfers between levels, and there was no significant activity within Level 3 financial instruments during the periods presented. See Note 14 for the carrying amount and estimated fair value of the Company's 1.75% Convertible Senior Notes due 2023 (the "Notes"). Assets and liabilities recognized or disclosed at fair value on a nonrecurring basis include items such as property, plant and equipment, goodwill and other intangible assets, cost method investments, and other assets. These assets are measured at fair value if determined to be impaired. The Company did not record any significant nonrecurring fair value measurements after initial recognition for the period ended September 30, 2019 . Gross unrealized holding gains and losses on available-for-sale debt securities were not material as of September 30, 2019.

Inventory

Inventory	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Inventory	Inventory September 30, 2019 December 31, 2018 Properties for sale $ 62,911 $ 12,649 Properties not available for sale 6,653 2,328 Properties under improvement 35,896 7,717 Inventory $ 105,460 $ 22,694 Inventory costs include direct property acquisition costs and any capitalized improvements, net of applicable lower of cost or net realizable value write-downs. As of September 30, 2019 and December 31, 2018 , lower of cost or net realizable value write-downs were $272 and $190 , respectively. Properties not available for sale represent purchased properties that have been temporarily rented back to the previous homeowner, typically for less than 30 days. Both properties not available for sale and properties under improvement are expected to be sold in less than twelve months. The following is the inventory activity for the nine months ended September 30, 2019: Nine Months Ended September 30, 2019 Inventory as of December 31, 2018 $ 22,694 Purchases and additions to inventory 213,813 Relief of inventory to cost of revenue (130,965 ) Lower of cost or net realizable value write-downs, net (82 ) Inventory as of September 30, 2019 $ 105,460

Property and Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment A summary of property and equipment as of September 30, 2019 and December 31, 2018 is as follows: Useful Lives (Years) September 30, 2019 December 31, 2018 Leasehold improvements Shorter of lease term or economic life $ 26,441 $ 19,285 Website and software development costs 2-3 25,629 19,948 Computer and office equipment 3 5,010 2,956 Software 3 595 595 Furniture 7 6,612 3,933 Property and equipment, gross 64,287 46,717 Accumulated depreciation and amortization (26,727 ) (21,530 ) Property and equipment, net $ 37,560 $ 25,187 Depreciation and amortization expense for property and equipment amounted to $2,453 and $2,099 for the three months ended September 30, 2019 and 2018 , respectively, and $6,018 and $5,757 for the nine months ended September 30, 2019 and 2018 , respectively.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases The extent of the Company’s lease commitments consists of operating leases for physical office locations with terms ranging from one to 11 years . The Company has accounted for the portfolio of operating leases by disaggregation based on the nature and term of the lease. Generally, the leases require a fixed minimum rent with contractual minimum rent increases over the lease term. Leases with an initial term of 12 months or less are not recorded on the balance sheet, but rather lease expense from these leases is recognized on a straight-line basis over the lease term. When available, the rate implicit in the lease to discount lease payments to present value would be used; however, none of the Company's significant leases as of September 30, 2019 provide a readily determinable implicit rate. Therefore, the Company must estimate its incremental borrowing rate for each portfolio of leases to discount the lease payments based on information available at lease commencement. The Company has evaluated the performance of existing leases in relation to its leasing strategy and determined that most renewal options would not be reasonably certain to be exercised. The right of use asset and related lease liability are determined based on the lease component of the consideration in each lease contract. The Company has evaluated its lease portfolio for appropriate allocation of the consideration in the lease contracts between lease and nonlease components based on standalone prices and determined the allocation per the contracts to be appropriate. Lease Cost Classification Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Operating lease cost (a) Cost of revenue $ 2,029 $ 5,814 Operating lease cost (a) Operating expenses 865 2,575 Total lease cost $ 2,894 $ 8,389 (a) Includes lease expense with initial terms of 12 months or less of $399 and $1,889 for the three months ended and nine months ended September 30, 2019, respectively. Maturity of Lease Liabilities Operating Leases 2019, excluding the nine months ended September 30, 2019 $ 2,013 2020 14,437 2021 14,111 2022 13,409 2023 12,533 Thereafter 27,757 Total lease payments $ 84,260 Less: Interest and other (a) (21,470 ) Present value of lease liabilities $ 62,790 (a) Interest and other consists of interest expense related to capitalized right of use lease liabilities of $9,050 , commitments related to leases that have not yet commenced and leases with initial terms of 12 months or less. Lease Term and Discount Rate September 30, 2019 Weighted average remaining operating lease term (years) 6.1 Weighted average discount rate for operating leases 4.4 % Supplemental Cash Flow Information Nine Months Ended September 30, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 7,040 Right of use assets obtained in exchange for lease liabilities Operating leases $ 50,263

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings — On August 28, 2019, one of the Company's former third-party licensed sales associates, which are referred to as associate agents, filed a complaint against the Company in the Superior Court of California, County of San Francisco. The complaint is pled as a class action and alleges that the Company misclassified the plaintiff as an independent contractor instead of an employee. The case includes representative claims under California’s Private Attorney General Act. The plaintiff is seeking unspecified amounts of unpaid overtime wages, straight time wages, meal and rest period compensation, penalties, injunctive, and other equitable relief, and reasonable attorneys' fees and costs. Given the preliminary stage of this case, the claims and issues presented, and the great uncertainties regarding which associate agents, if any, may be part of a class if one is certified, the Company cannot estimate a range of reasonably possible losses. In addition to the matter discussed above, from time to time, the Company is involved in litigation, claims, and other proceedings arising in the ordinary course of its business. Such litigation and other proceedings may include, but are not limited to, actions or claims relating to employment law (including misclassification), intellectual property, privacy and consumer protection, the Real Estate Settlement Procedures Act of 1974, the Fair Housing Act of 1968 or other fair housing statutes, cybersecurity incidents, data breaches or misappropriation, and commercial or contractual disputes. They may also relate to ordinary-course brokerage disputes, including, but not limited to, failure to disclose property defects, failure to meet client legal obligations, commission disputes, personal injury or property damage claims, and vicarious liability based upon conduct of individuals or entities outside of the Company's control, including partner agents and third-party contractor agents. Facility Leases and Other Commitments —The Company leases its office space under noncancelable operating leases with terms ranging from one to 11 years. Generally, the leases require a fixed minimum rent with contractual minimum rent increases over the lease term, and certain leases include escalation provisions. Other commitments primarily relate to homes that the Company is under contract to purchase through its properties segment but that have not closed, and network infrastructure for the Company’s data operations. Future minimum payments due under these agreements as of September 30, 2019 are as follows: Facility Leases (a) Other Commitments 2019, excluding the nine months ended September 30, 2019 $ 2,013 $ 26,796 2020 14,437 3,726 2021 14,111 1,173 2022 13,409 1,138 2023 and thereafter 40,290 — Total minimum lease payments $ 84,260 $ 32,833 (a) The future minimum lease payments are presented on the same basis as the financial information presented in audited consolidated financial statements and notes for the year ended December 31, 2018 included in the 2018 Annual Report.

Acquired Intangible Assets

Acquired Intangible Assets	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Acquired Intangible Assets	Acquired Intangible Assets The following table presents details of the Company's intangible assets subject to amortization as of the dates presented: September 30, 2019 December 31, 2018 Useful Gross Accumulated Amortization Net Gross Accumulated Amortization Net Trade names 10 $ 1,040 $ (520 ) $ 520 $ 1,040 $ (442 ) $ 598 Developed technology 10 2,980 (1,490 ) 1,490 2,980 (1,266 ) 1,714 Customer relationships 10 860 (430 ) 430 860 (366 ) 494 $ 4,880 $ (2,440 ) $ 2,440 $ 4,880 $ (2,074 ) $ 2,806 Acquired intangible assets are amortized using the straight-line method over their estimated useful life, which approximates the expected use of these assets. Amortization expense amounted to $122 and $366 for each of the three and nine months ended September 30, 2019 and 2018 . Amortization expense of $2,440 will be recognized over the next five years, or $488 per year.

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities The following table presents the detail of accrued liabilities as of the dates presented: September 30, 2019 December 31, 2018 Accrued compensation and benefits $ 40,234 $ 22,862 Miscellaneous accrued liabilities 10,633 7,975 Total accrued liabilities $ 50,867 $ 30,837

Other Payables

Other Payables	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Other Payables	Other Payables Other payables consists primarily of customer deposits for cash held in escrow on behalf of real estate buyers using Title Forward, the Company's wholly owned title and settlement services subsidiary. Since the Company does not have rights to the cash, the customer deposits are recorded as a liability with a corresponding asset in the same amount recorded within restricted cash. The following table presents the detail of other payables as of the dates presented: September 30, 2019 December 31, 2018 Customer deposits $ 6,863 $ 6,226 Miscellaneous payables 294 318 Total other payables $ 7,157 $ 6,544

Equity and Employee Stock Plans

Equity and Employee Stock Plans	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Equity and Employee Stock Plans	Equity and Employee Stock Plans Common Stock —At September 30, 2019 and December 31, 2018 , the Company was authorized to issue 500,000,000 shares of common stock with a par value of $0.001 per share. Preferred Stock — As of September 30, 2019 and December 31, 2018 , the Company was authorized to issue 10,000,000 shares of preferred stock with a par value of $0.001 , of which no shares were issued or outstanding. 2017 Equity Incentive Plan — The Company's 2017 Equity Incentive Plan ("2017 EIP") became effective on July 26, 2017, and provides for the issuance of incentive and nonqualified common stock options and restricted stock units to employees, directors, officers, and consultants of the Company. The number of shares of common stock initially reserved for issuance under the 2017 EIP was 7,898,159 . The number of shares reserved for issuance under the 2017 EIP will increase automatically on January 1 of each calendar year beginning on January 1, 2018, and continuing through January 1, 2028, by the number of shares equal to the lesser of 5% of the total outstanding shares of the Company's common stock as of the immediately preceding December 31 or an amount determined by the board of directors. Amended and Restated 2004 Equity Incentive Plan — The Company granted options under its 2004 Equity Incentive Plan, as amended ("2004 Plan"), until July 26, 2017, when the plan was terminated in connection with the Company’s initial public offering. Accordingly, no shares are available for future issuance under the 2004 Plan. The 2004 Plan continues to govern outstanding equity awards granted thereunder. 2017 Employee Stock Purchase Plan —T he Company initially reserved 1,600,000 shares of common stock for issuance under the 2017 Employee Stock Purchase Plan (the "2017 ESPP"). The number of shares reserved for issuance under the 2017 ESPP will increase automatically on January 1 of each calendar year beginning after the first offering date and continuing through January 1, 2028, by the number of shares equal to the lesser of 1% of the total outstanding shares of the Company’s common stock as of the immediately preceding December 31 or an amount determined by the board of directors. During the three and nine months ended September 30, 2019, zero and 262,110 shares of common stock, respectively, were issued under the 2017 ESPP. The Company has reserved shares of common stock, on an as-converted basis, for future issuance as follows: September 30, 2019 December 31, 2018 Equity Incentive Plans Shares underlying outstanding stock options 8,102,171 9,435,349 Shares underlying outstanding restricted stock units 4,536,677 3,264,702 Shares available for future equity grants 7,837,918 5,068,013 Total shares reserved for issuance 20,476,766 17,768,064 2017 Employee Stock Purchase Plan Shares available for issuance on January 1, 2019 and 2018, respectively 2,890,973 2,414,688 Shares issued since January 1, 2019 and 2018, respectively (262,110 ) (425,228 ) Total shares available for future issuance 2,628,863 1,989,460 Stock Options— The following table summarizes activity for stock options for the nine months ended September 30, 2019 : Weighted- Average Exercise Price Weighted-Average Remaining Contractual Life (Years) Outstanding as of December 31, 2018 9,435,349 $ 6.48 6.06 $ 74,669 Options granted 150,000 27.50 Options exercised (1,397,074) 5.49 Options forfeited (81,826) 9.16 Options canceled (4,278) 8.22 Outstanding as of September 30, 2019 8,102,171 7.01 5.59 81,204 Options exercisable as of September 30, 2019 7,100,240 6.30 5.32 74,839 The grant date fair value of options to purchase common stock is recorded as stock-based compensation over the vesting period. As of September 30, 2019 , there was $4,092 of total unrecognized compensation cost related to options to purchase common stock, which is expected to be recognized over a weighted-average period of 1.25 years. On June 1, 2019, the Company granted stock options subject to performance conditions, with a target of 150,000 shares and a maximum 300,000 shares, to the Company's Chief Executive Officer. The options have an exercise price of $27.50 per share and have the same performance and vesting conditions as the restricted stock units subject to performance conditions that the Company granted in 2019 (the "2019 PSUs"). Restricted Stock Units— The following table summarizes activity for restricted stock units for the nine months ended September 30, 2019 : Restricted Stock Units Weighted-Average Grant Date Fair Value Unvested outstanding as of December 31, 2018 3,264,702 $ 19.68 Granted 2,102,975 17.79 Vested (562,755 ) 21.00 Forfeited (268,245 ) 20.06 Unvested outstanding as of September 30, 2019 4,536,677 18.62 The grant date fair value of restricted stock units is recorded as stock-based compensation over the vesting period. As of September 30, 2019 , there was $76,009 of total unrecognized compensation cost related to restricted stock units, which is expected to be recognized over a weighted-average period of 3.08 years. As of September 30, 2019 , there were outstanding 279,826 restricted stock units subject to performance conditions (the "PSUs") at 100% of the target level. During the nine months ended September 30, 2019 , a net ($126) for share-based compensation expense was recognized for the PSUs, which includes (i) an adjustment of ($610) related to the PSUs granted in 2018 as the probability of achieving the performance conditions was determined to be not probable and (ii) a charge of $484 related to the 2019 PSUs. Compensation Cost —The following table details, for each period indicated, (i) the Company's stock-based compensation net of forfeitures, and the amount capitalized in internally developed software and (ii) includes changes to the probability of achieving outstanding performance-based equity awards, each as included in the Company’s condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Cost of revenue $ 1,605 $ 1,370 $ 4,398 $ 4,061 Technology and development 3,320 2,135 8,661 5,335 Marketing 390 155 1,025 431 General and administrative 2,195 1,838 5,708 4,646 Total stock-based compensation $ 7,510 $ 5,498 $ 19,792 $ 14,473

Net Income (Loss) per Share

Net Income (Loss) per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Net Income (Loss) per Share	Net Income (Loss) per Share Net income (loss) per share is computed by dividing the net income (loss) by the weighted-average number of shares of common stock outstanding. The Company has outstanding stock options, restricted stock units, options to purchase shares under its employee stock purchase plan, and convertible senior notes, which are considered in the calculation of diluted net income (loss) per share whenever doing so would be dilutive. The following table sets forth the calculation of basic and diluted net income (loss) per share during the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Numerator Net income (loss) $ 6,782 $ 3,475 $ (73,023 ) $ (29,756 ) Denominator Weighted average shares: Basic 91,994,731 87,743,223 91,279,086 84,327,266 Dilutive shares from stock plans 5,176,539 6,899,240 — — Diluted 97,171,270 94,642,463 91,279,086 84,327,266 Net income (loss) per share Net income (loss) per share - basic $ 0.07 $ 0.04 $ (0.80 ) $ (0.35 ) Net income (loss) per share - diluted $ 0.07 $ 0.04 $ (0.80 ) $ (0.35 ) The following outstanding shares of common stock equivalents as of September 30, 2019 and 2018 were excluded from the computation of the diluted net income (loss) per share for the periods presented because their effect would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Options to purchase common stock — — 8,102,171 10,150,522 Restricted stock units 1,744,366 238,668 4,536,677 2,081,173 Employee stock purchase plan shares — — 283,676 234,616 Total 1,744,366 238,668 12,922,524 12,466,311 There is no impact from the Notes on the Company's diluted net loss per share for the three and nine months ended September 30, 2019

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s effective tax rate for the nine months ended September 30, 2019 and 2018 was 0% as a result of the Company recording a full valuation allowance against the deferred tax assets. In determining the realizability of the net U.S. federal and state deferred tax assets, the Company considers numerous factors including historical profitability, estimated future taxable income, prudent and feasible tax planning strategies and the industry in which it operates. Management reassesses the realization of the deferred tax assets each reporting period, which resulted in a valuation allowance against the full amount of the Company’s U.S. deferred tax assets for the nine months ended September 30, 2019 and 2018. To the extent that the financial results of the U.S. operations improve in the future and the deferred tax assets become realizable, the Company will reduce the valuation allowance through earnings. Under Section 382 of the Internal Revenue Code of 1986, as amended, substantial changes in the Company's ownership may limit the amount of net operating loss carryforwards that could be utilized annually in the future to offset taxable income. Any such annual limitation may significantly reduce the utilization of the net operating losses before they expire. A Section 382 limitation study performed as of March 31, 2017 determined there was an ownership change in 2006 and $1,538 of the 2006 net operating loss is unavailable. As of December 31, 2018, the Company had accumulated approximately $125,850 of federal tax losses, approximately $6,180 (tax effected) of state tax losses. Federal net operating losses are available to offset federal taxable income and begin to expire in 2025. Federal net operating loss carryforwards of $39,365 generated during 2018 are available to offset future U.S. federal taxable income over an indefinite period. The Company’s material income tax jurisdiction is the United States (federal). As a result of net operating loss carryforwards, the Company is subject to audit for tax years 2005 and forward for federal purposes. There are tax years which remain subject to examination in various other jurisdictions that are not material to the Company’s financial statements.

Convertible Senior Notes

Convertible Senior Notes	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt Warehouse Credit Facilities —To provide capital for the mortgage loans that it originates, Redfin Mortgage, the Company's wholly owned mortgage origination subsidiary, utilizes warehouse credit facilities that are classified as current liabilities in the Company's condensed consolidated balance sheets. The following table summarizes borrowings under these facilities as of the periods presented: Lender Borrowing Capacity as of September 30, 2019 Borrowings as of September 30, 2019 Borrowings as of December 31, 2018 Western Alliance Bank $ 24,500 $ 11,522 $ 1,141 Texas Capital Bank, N.A. 24,500 10,465 3,592 Total $ 49,000 $ 21,987 $ 4,733 Borrowings under the facility with Western Alliance Bank ("Western Alliance") mature on June 15, 2020 and generally bear interest at a rate equal to the greater of (i) one-month LIBOR plus 2.00% or (ii) 3.50% . The agreement governing the facility requires Redfin Mortgage to maintain certain financial covenants. Redfin Mortgage is in default of this facility because it failed to satisfy a financial covenant as of September 30, 2019, but Western Alliance has not enforced its remedy under the agreement of requiring Redfin Mortgage to repurchase all outstanding loans held by the lender. Borrowings under the facility with Texas Capital Bank, N.A. ("Texas Capital") mature on May 6, 2020 and generally bear interest at a rate equal to the greater of (i) the rate of interest accruing on the outstanding principal balance of the loan minus 0.5% or (ii) 3.5% . Due to Redfin Mortgage's failure to satisfy a financial covenant under the Western Alliance facility, it is in default of the Texas Capital facility. However, Texas Capital has not enforced its remedies under the agreement, which principally include the rights to (i) cease purchasing participation interests in loans from Redfin Mortgage and (ii) sell all interests of Texas Capital or Redfin Mortgage in any loan subject to the agreement. Redfin Corporation has guaranteed Redfin Mortgage’s obligations under the agreement. Secured Revolving Credit Facility —To provide capital for the properties that it purchases, RedfinNow, the Company's subsidiary that buys homes directly from homeowners and resell them to homebuyers, has, through a special purpose entity ("SPE"), entered into a secured revolving credit facility with Goldman Sachs Bank USA. The following table summarizes borrowings under this facility as of the period presented: Lender Borrowing Capacity as of September 30, 2019 Borrowings as of Goldman Sachs Bank USA $ 100,000 $ — The facility matures on January 26, 2021, but the Company may extend the maturity date for an additional six months to repay outstanding borrowings. Borrowings under the facility generally bear interest at a rate of one-month LIBOR (subject to a floor of 0.50% ) plus 2.65% . In instances involving "bad acts," Redfin Corporation has guaranteed repayment of amounts owed under the facility, in some situations, and indemnification of certain expenses incurred, in other situations. For the three months ended September 30, 2019, the Company amortized $102 of the debt issuance costs. Convertible Senior Notes — On July 23, 2018, the Company issued $143,750 aggregate principal amount of Notes. The Notes are senior, unsecured obligations of Redfin, and bear interest at a fixed rate of 1.75% per year, payable semi-annually in arrears on January 15 and July 15. The effective interest rate of the liability portion of the debt is 7.25% . The Notes mature on July 15, 2023, unless earlier repurchased, redeemed or converted. As of September 30, 2019 , no conversion events have occurred. The Company will settle conversions of the Notes by paying or delivering, as the case may be, cash, shares of its common stock, or a combination of cash and shares of its common stock, at its election. The Company has the ability, and intends, to settle any conversions solely in cash. The Notes consisted of the following: September 30, 2019 December 31, 2018 Principal $ 143,750 $ 143,750 Less: debt discount, net of amortization (22,605 ) (26,636 ) Less: debt issuance costs, net of amortization (2,987 ) (3,528 ) Net carrying amount of the Notes $ 118,158 $ 113,586 The total estimated fair value of the Notes as of September 30, 2019 and December 31, 2018 was approximately $131,028 and $117,875 , respectively, based on the closing trading price of the Notes on last day of trading for the period. The fair value has been classified as Level 2 within the fair value hierarchy given the limited trading activity of the Notes. The following table sets forth total interest expense recognized related to the Notes for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Amortization of debt discount $ 1,359 $ 997 $ 4,031 $ 997 Amortization of debt issuance costs 182 131 541 131 Total amortization of debt issuance costs and accretion of equity portion 1,541 1,128 4,572 1,128 Contractual interest expense 629 482 1,887 482 Total interest expense related to the Notes $ 2,170 $ 1,610 $ 6,459 $ 1,610

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Flagstar Warehouse Credit Facility —In October 2019, Redfin Mortgage entered into a Mortgage Warehousing Loan and Security Agreement with Flagstar Bank, FSB ("Flagstar"). Under this warehouse credit facility, Redfin Mortgage may receive funds from Flagstar to finance eligible mortgage loans that it has originated. The facility has a maximum borrowing capacity of $15,000 , and borrowings under the facility generally bear interest at a rate equal to the greater of (i) one-month LIBOR plus 2.00% or (ii) 3.00%

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation —The consolidated financial statements and accompanying notes have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). All amounts are presented in thousands, except share and per share amounts. The financial information as of December 31, 2018 that is included in this Quarterly Report is derived from the audited consolidated financial statements and notes for the year ended December 31, 2018 included in Item 8 in the Annual Report on Form 10-K (the “2018 Annual Report”) of Redfin Corporation (the "Company" or "Redfin"). Such financial information should be read in conjunction with the notes and management’s discussion and analysis of the consolidated financial statements included in the 2018 Annual Report. The unaudited condensed consolidated financial statements, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly the Company's financial position as of September 30, 2019 , the statements of comprehensive income (loss) and stockholders' equity for the three and nine months ended September 30, 2019 and 2018 , and the statement of cash flows for the nine months ended September 30, 2019 and 2018. The results for the three and nine months ended September 30, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019 or for any interim period or for any other future year.
Principles of Consolidation	Principles of Consolidation —The unaudited condensed consolidated interim financial statements include the accounts of Redfin and its wholly owned subsidiaries. Intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates — The preparation of consolidated financial statements, in conformity with GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and results of operations during the respective periods. The Company evaluates its estimates on an ongoing basis. During the nine months ended September 30, 2019 , the estimated useful life of capitalized software for internal use was updated from one to two years . This change in estimate was not material. In addition, with the adoption of Accounting Standards Codification Topic 842, Leases , the Company estimated its incremental borrowing rate for the determination of the present value of lease payments. Further description of the impact of this pronouncement is included in Note 6. The amounts ultimately realized from the affected assets or liabilities will depend on, among other factors, general business conditions and could differ materially in the near term from the carrying amounts reflected in the consolidated financial statements.
Cash and Cash Equivalents	Cash and Cash Equivalents —Cash equivalents consist primarily of money market instruments and U.S. treasury securities. The Company considers all highly liquid investments originally purchased by the Company with original maturities of three months or less at the date of purchase to be cash equivalents and classified as available-for-sale.
Investments	Investments —The Company has two types of investments: (i) available-for-sale investments that are available to support operational needs of the Company, which are reported on the balance sheet as short-term and long-term investments, and (ii) long-term equity investments accounted for under the cost method, which are reported in other non-current assets. Available-for-sale The Company's short-term and long-term investments consist primarily of U.S. treasury securities, all of which are classified as available-for-sale. Available-for-sale debt securities are recorded at fair value, and unrealized holding gains and losses are recorded as a component of accumulated other comprehensive income. Available-for-sale securities with maturities of one year or less and those identified by management at the time of purchase to be used to fund operations within one year are classified as short-term. All other available-for-sale securities are classified as long-term. The Company evaluates its available-for-sale securities, both ones classified as cash equivalents and as investments, for other-than-temporary impairment on a quarterly basis. Unrealized losses are charged against net earnings when a decline in fair value is determined to be other than temporary. The Company reviews factors to determine whether a loss is other than temporary, such as the length and extent of the fair value decline, the financial condition and near-term prospects of the issuer, and whether the Company has the intent to sell or will more likely than not be required to sell before the securities' anticipated recovery, which may be at maturity. Realized gains and losses are accounted for using the specific identification method. Purchases and sales are recorded on a trade date basis. There were no other than temporary impairments during the periods presented. Cost Method Investments In December 2018, the Company purchased an equity interest in a privately held company for approximately $2,000 , which is classified as long-term. The investment is an equity security without a readily determinable fair value that is accounted for at cost minus any impairment, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments of the same issuer. The Company performs a qualitative assessment considering impairment indicators to evaluate whether the investment is impaired as of the end of each reporting period.
Advertising and Advertising Production Costs	Advertising and Advertising Production Costs —The Company expenses advertising costs as they are incurred and production costs as of the first date the advertisement takes place. Advertising costs totaled $5,279 and $5,936 for the three months ended September 30, 2019 and 2018 , respectively, and $59,357 and $29,167 for the nine months ended September 30, 2019 and 2018 , respectively, and are included in marketing expenses. Advertising production costs totaled $17 and $7 for the three months ended September 30, 2019 and 2018 , respectively, and $166 and $20 for the nine months ended September 30, 2019 and 2018 , respectively, and are included in marketing expenses.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements —In January 2019, the Company adopted ASU 2016-02, Leases (Topic 842) , using the optional alternative transition method under ASU 2018-11, Leases (Topic 842) Targeted Improvements . The optional alternative transition method applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company evaluated its portfolio of leases and determined a cumulative-effect adjustment to the opening balance of retained earnings was not needed, as the portfolio of leases contains only operating leases. The Company elected the package of practical expedients permitted under the transition guidance within the standard, allowing the Company to carry forward the historical lease classification, carry forward the conclusions on whether current or expired contracts contain leases, and carry forward the accounting for initial direct costs for existing leases. Additionally, the Company elected the practical expedient for use of hindsight to determine the lease term for existing leases whereby it evaluated the performance of existing leases in relation to our leasing strategy and determined that most renewal options would not be reasonably certain to be exercised. This resulted in the shortening of lease terms for the existing leases. Adoption of the standard resulted in the recording of right of use assets and corresponding lease liabilities of $33,953 and $49,395 , respectively, as of January 1, 2019, the difference of which is due to lease incentives. Further description of the impact of this pronouncement is included in Note 6. In January 2019, the Company adopted the guidance in the U.S. Securities and Exchange Commission (the "SEC") final rule under SEC Release No. 33-10532, Disclosure Update and Simplification. In August 2018, the SEC issued the final rule amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated, or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. In August 2018, the Financial Accounting Standards Board ("FASB") issued authoritative guidance under ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract . The ASU requires implementation costs incurred by customers in cloud computing arrangements (i.e., hosting arrangements) to be capitalized under the same premises of authoritative guidance for internal-use software, and deferred over the noncancelable term of the cloud computing arrangements plus any option renewal periods that are reasonably certain to be exercised by the customer or for which the exercise is controlled by the service provider. The ASU is effective for public entities for fiscal years beginning after December 15, 2019 and early adoption is permitted. The Company elected to early adopt this standard in the third quarter of 2019 on a prospective basis, which did not result in a material effect on the Company's consolidated financial statements. Recently Issued Accounting Pronouncements — In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) , which modifies the disclosures on fair value measurements by removing the requirement to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy and the policy for timing of such transfers. The ASU expands the disclosure requirements for Level 3 fair value measurements, primarily focused on changes in unrealized gains and losses included in other comprehensive income. The ASU is effective for public entities for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company has not yet completed its assessment of the impact of the new standard on the Company’s consolidated financial statements. In June 2016, the FASB issued authoritative guidance under ASU 2016-13, Financial Instruments—Credit Losses (Topic 326), which modifies the measurement of credit losses on financial instruments. This guidance requires the use of an expected loss impairment model for instruments measured at amortized cost based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. For available-for-sale debt securities, an entity is required to recognize credit losses through an allowance for credit losses rather than as an impairment. The ASU is effective for interim and annual reporting periods beginning after December 15, 2019, and early adoption is permitted. The adoption of this guidance requires a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company completed its assessment of the impact of the new standard on the Company’s consolidated financial statements and does not expect a material impact.

Segment Reporting and Revenue (

Segment Reporting and Revenue (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Reconciliation of Operating Profit (Loss) from Segments to Consolidated	Information on each of the reportable and other segments and reconciliation to consolidated net income (loss) is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Real estate services Brokerage revenue $ 146,096 $ 118,809 $ 372,809 $ 312,306 Partner revenue 8,030 7,456 20,053 19,741 Total real estate services revenue 154,126 126,265 392,862 332,047 Cost of revenue 100,048 83,274 284,447 236,775 Gross profit 54,078 42,991 108,415 95,272 Properties Revenue 80,164 11,350 141,445 23,388 Cost of revenue 80,909 11,656 144,807 24,086 Gross profit (745 ) (306 ) (3,362 ) (698 ) Other Revenue 5,161 2,691 13,490 7,407 Cost of revenue 5,117 3,071 14,065 8,766 Gross profit 44 (380 ) (575 ) (1,359 ) Intercompany eliminations Revenue (768 ) (51 ) (1,192 ) (51 ) Cost of revenue (768 ) $ (51 ) (1,192 ) (51 ) Gross profit — — — — Consolidated Revenue 238,683 140,255 546,605 362,791 Cost of revenue 185,306 97,950 442,127 269,576 Gross profit 53,377 42,305 104,478 93,215 Operating expenses 45,941 39,016 176,913 124,643 Interest income 1,576 1,775 5,804 3,082 Interest expense (2,274 ) (1,610 ) (6,564 ) (1,610 ) Other income, net 44 21 172 200 Net income (loss) $ 6,782 $ 3,475 $ (73,023 ) $ (29,756 )
Contract with Customer, Asset and Liability	The following table presents the detail of accrued revenue for the periods presented: Nine Months Ended September 30, 2019 2018 Accrued revenue $ 24,703 $ 13,411 Less: Allowance for doubtful accounts (269 ) (157 ) Accrued revenue, net $ 24,434 $ 13,254 The following table presents the activity in the allowance for doubtful accounts for the period presented: Nine Months Ended September 30, 2019 2018 Balance, beginning of period $ 166 $ 160 Charges 128 23 Write-offs (25 ) (26 ) Balance, end of period $ 269 $ 157

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Schedule of Assets, Liabilities, and Equity Measured at Fair Value on a Recurring Basis	A summary of assets and liabilities as of September 30, 2019 and December 31, 2018 , related to the Company's financial instruments measured at fair value on a recurring basis, is set forth below, along with the balance sheet accounts they are classified within: Balance as of September 30, 2019 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash equivalents Money market funds $ 198,172 $ 198,172 $ — $ — U.S. treasury securities 282 — 282 — Short-term investments U.S. treasury securities 62,054 — 62,054 — Loans held for sale 22,246 — 22,246 — Prepaid expenses and other current assets Forward sales commitments 216 — 216 — Interest rate lock commitments 603 — — 603 Total prepaid expenses and other current assets 819 — 216 603 Long-term investments U.S. treasury securities 38,480 — 38,480 — Total assets $ 322,053 $ 198,172 $ 123,278 $ 603 Liabilities Accrued liabilities Forward sales commitments $ 44 $ — $ 44 $ — Interest rate lock commitments 124 — — 124 Total liabilities $ 168 $ — $ 44 $ 124 Balance as of December 31, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Cash equivalents Money market funds $ 425,776 $ 425,776 $ — $ — Loans held for sale 4,913 — 4,913 — Prepaid expenses and other current assets Interest rate lock commitments 254 — — 254 Total prepaid expenses and other current assets 254 — — 254 Total assets $ 430,943 $ 425,776 $ 4,913 $ 254 Liabilities Accrued liabilities Forward sales commitments $ 141 $ — $ 141 $ — Total liabilities $ 141 $ — $ 141 $ —

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	September 30, 2019 December 31, 2018 Properties for sale $ 62,911 $ 12,649 Properties not available for sale 6,653 2,328 Properties under improvement 35,896 7,717 Inventory $ 105,460 $ 22,694 The following is the inventory activity for the nine months ended September 30, 2019: Nine Months Ended September 30, 2019 Inventory as of December 31, 2018 $ 22,694 Purchases and additions to inventory 213,813 Relief of inventory to cost of revenue (130,965 ) Lower of cost or net realizable value write-downs, net (82 ) Inventory as of September 30, 2019 $ 105,460

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	A summary of property and equipment as of September 30, 2019 and December 31, 2018 is as follows: Useful Lives (Years) September 30, 2019 December 31, 2018 Leasehold improvements Shorter of lease term or economic life $ 26,441 $ 19,285 Website and software development costs 2-3 25,629 19,948 Computer and office equipment 3 5,010 2,956 Software 3 595 595 Furniture 7 6,612 3,933 Property and equipment, gross 64,287 46,717 Accumulated depreciation and amortization (26,727 ) (21,530 ) Property and equipment, net $ 37,560 $ 25,187

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lease, Cost	Lease Cost Classification Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Operating lease cost (a) Cost of revenue $ 2,029 $ 5,814 Operating lease cost (a) Operating expenses 865 2,575 Total lease cost $ 2,894 $ 8,389 (a) Includes lease expense with initial terms of 12 months or less of $399 and $1,889 for the three months ended and nine months ended September 30, 2019, respectively. Lease Term and Discount Rate September 30, 2019 Weighted average remaining operating lease term (years) 6.1 Weighted average discount rate for operating leases 4.4 % Supplemental Cash Flow Information Nine Months Ended September 30, 2019 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 7,040 Right of use assets obtained in exchange for lease liabilities Operating leases $ 50,263
Lessee, Operating Lease, Liability, Maturity	Maturity of Lease Liabilities Operating Leases 2019, excluding the nine months ended September 30, 2019 $ 2,013 2020 14,437 2021 14,111 2022 13,409 2023 12,533 Thereafter 27,757 Total lease payments $ 84,260 Less: Interest and other (a) (21,470 ) Present value of lease liabilities $ 62,790 (a) Interest and other consists of interest expense related to capitalized right of use lease liabilities of $9,050 , commitments related to leases that have not yet commenced and leases with initial terms of 12 months or less. September 30, 2019 are as follows: Facility Leases (a) Other Commitments 2019, excluding the nine months ended September 30, 2019 $ 2,013 $ 26,796 2020 14,437 3,726 2021 14,111 1,173 2022 13,409 1,138 2023 and thereafter 40,290 — Total minimum lease payments $ 84,260 $ 32,833 (a) The future minimum lease payments are presented on the same basis as the financial information presented in audited consolidated financial statements and notes for the year ended December 31, 2018 included in the 2018 Annual Report.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Lessee, Operating Lease, Liability, Maturity	Maturity of Lease Liabilities Operating Leases 2019, excluding the nine months ended September 30, 2019 $ 2,013 2020 14,437 2021 14,111 2022 13,409 2023 12,533 Thereafter 27,757 Total lease payments $ 84,260 Less: Interest and other (a) (21,470 ) Present value of lease liabilities $ 62,790 (a) Interest and other consists of interest expense related to capitalized right of use lease liabilities of $9,050 , commitments related to leases that have not yet commenced and leases with initial terms of 12 months or less. September 30, 2019 are as follows: Facility Leases (a) Other Commitments 2019, excluding the nine months ended September 30, 2019 $ 2,013 $ 26,796 2020 14,437 3,726 2021 14,111 1,173 2022 13,409 1,138 2023 and thereafter 40,290 — Total minimum lease payments $ 84,260 $ 32,833 (a) The future minimum lease payments are presented on the same basis as the financial information presented in audited consolidated financial statements and notes for the year ended December 31, 2018 included in the 2018 Annual Report.
Other Commitments	Future minimum payments due under these agreements as of September 30, 2019 are as follows: Facility Leases (a) Other Commitments 2019, excluding the nine months ended September 30, 2019 $ 2,013 $ 26,796 2020 14,437 3,726 2021 14,111 1,173 2022 13,409 1,138 2023 and thereafter 40,290 — Total minimum lease payments $ 84,260 $ 32,833 (a) The future minimum lease payments are presented on the same basis as the financial information presented in audited consolidated financial statements and notes for the year ended December 31, 2018 included in the 2018 Annual Report.

Acquired Intangible Assets (Tab

Acquired Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The following table presents details of the Company's intangible assets subject to amortization as of the dates presented: September 30, 2019 December 31, 2018 Useful Gross Accumulated Amortization Net Gross Accumulated Amortization Net Trade names 10 $ 1,040 $ (520 ) $ 520 $ 1,040 $ (442 ) $ 598 Developed technology 10 2,980 (1,490 ) 1,490 2,980 (1,266 ) 1,714 Customer relationships 10 860 (430 ) 430 860 (366 ) 494 $ 4,880 $ (2,440 ) $ 2,440 $ 4,880 $ (2,074 ) $ 2,806

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	The following table presents the detail of accrued liabilities as of the dates presented: September 30, 2019 December 31, 2018 Accrued compensation and benefits $ 40,234 $ 22,862 Miscellaneous accrued liabilities 10,633 7,975 Total accrued liabilities $ 50,867 $ 30,837

Other Payables (Tables)

Other Payables (Tables)	9 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Schedule of Other Payables	The following table presents the detail of other payables as of the dates presented: September 30, 2019 December 31, 2018 Customer deposits $ 6,863 $ 6,226 Miscellaneous payables 294 318 Total other payables $ 7,157 $ 6,544

Equity and Employee Stock Pla_2

Equity and Employee Stock Plans (Tables)	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Reserved Shares of Common Stock	The Company has reserved shares of common stock, on an as-converted basis, for future issuance as follows: September 30, 2019 December 31, 2018 Equity Incentive Plans Shares underlying outstanding stock options 8,102,171 9,435,349 Shares underlying outstanding restricted stock units 4,536,677 3,264,702 Shares available for future equity grants 7,837,918 5,068,013 Total shares reserved for issuance 20,476,766 17,768,064 2017 Employee Stock Purchase Plan Shares available for issuance on January 1, 2019 and 2018, respectively 2,890,973 2,414,688 Shares issued since January 1, 2019 and 2018, respectively (262,110 ) (425,228 ) Total shares available for future issuance 2,628,863 1,989,460
Schedule of Stock Option Activity	The following table summarizes activity for stock options for the nine months ended September 30, 2019 : Weighted- Average Exercise Price Weighted-Average Remaining Contractual Life (Years) Outstanding as of December 31, 2018 9,435,349 $ 6.48 6.06 $ 74,669 Options granted 150,000 27.50 Options exercised (1,397,074) 5.49 Options forfeited (81,826) 9.16 Options canceled (4,278) 8.22 Outstanding as of September 30, 2019 8,102,171 7.01 5.59 81,204 Options exercisable as of September 30, 2019 7,100,240 6.30 5.32 74,839
Schedule of Nonvested Restricted Stock Units Activity	The following table summarizes activity for restricted stock units for the nine months ended September 30, 2019 : Restricted Stock Units Weighted-Average Grant Date Fair Value Unvested outstanding as of December 31, 2018 3,264,702 $ 19.68 Granted 2,102,975 17.79 Vested (562,755 ) 21.00 Forfeited (268,245 ) 20.06 Unvested outstanding as of September 30, 2019 4,536,677 18.62
Schedule of Allocation of Share-based Compensation Costs	The following table details, for each period indicated, (i) the Company's stock-based compensation net of forfeitures, and the amount capitalized in internally developed software and (ii) includes changes to the probability of achieving outstanding performance-based equity awards, each as included in the Company’s condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Cost of revenue $ 1,605 $ 1,370 $ 4,398 $ 4,061 Technology and development 3,320 2,135 8,661 5,335 Marketing 390 155 1,025 431 General and administrative 2,195 1,838 5,708 4,646 Total stock-based compensation $ 7,510 $ 5,498 $ 19,792 $ 14,473

Net Income (Loss) per Share (Ta

Net Income (Loss) per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Earnings Per Share	The following table sets forth the calculation of basic and diluted net income (loss) per share during the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Numerator Net income (loss) $ 6,782 $ 3,475 $ (73,023 ) $ (29,756 ) Denominator Weighted average shares: Basic 91,994,731 87,743,223 91,279,086 84,327,266 Dilutive shares from stock plans 5,176,539 6,899,240 — — Diluted 97,171,270 94,642,463 91,279,086 84,327,266 Net income (loss) per share Net income (loss) per share - basic $ 0.07 $ 0.04 $ (0.80 ) $ (0.35 ) Net income (loss) per share - diluted $ 0.07 $ 0.04 $ (0.80 ) $ (0.35 )
Summary of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following outstanding shares of common stock equivalents as of September 30, 2019 and 2018 were excluded from the computation of the diluted net income (loss) per share for the periods presented because their effect would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Options to purchase common stock — — 8,102,171 10,150,522 Restricted stock units 1,744,366 238,668 4,536,677 2,081,173 Employee stock purchase plan shares — — 283,676 234,616 Total 1,744,366 238,668 12,922,524 12,466,311

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt	The following table summarizes borrowings under this facility as of the period presented: Lender Borrowing Capacity as of September 30, 2019 Borrowings as of Goldman Sachs Bank USA $ 100,000 $ — The following table summarizes borrowings under these facilities as of the periods presented: Lender Borrowing Capacity as of September 30, 2019 Borrowings as of September 30, 2019 Borrowings as of December 31, 2018 Western Alliance Bank $ 24,500 $ 11,522 $ 1,141 Texas Capital Bank, N.A. 24,500 10,465 3,592 Total $ 49,000 $ 21,987 $ 4,733 The Notes consisted of the following: September 30, 2019 December 31, 2018 Principal $ 143,750 $ 143,750 Less: debt discount, net of amortization (22,605 ) (26,636 ) Less: debt issuance costs, net of amortization (2,987 ) (3,528 ) Net carrying amount of the Notes $ 118,158 $ 113,586
Interest Income and Interest Expense Disclosure	The following table sets forth total interest expense recognized related to the Notes for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Amortization of debt discount $ 1,359 $ 997 $ 4,031 $ 997 Amortization of debt issuance costs 182 131 541 131 Total amortization of debt issuance costs and accretion of equity portion 1,541 1,128 4,572 1,128 Contractual interest expense 629 482 1,887 482 Total interest expense related to the Notes $ 2,170 $ 1,610 $ 6,459 $ 1,610

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Narrative (Details)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)investment_type	Sep. 30, 2018USD ($)	Dec. 31, 2018	Jan. 01, 2019USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of types of investments | investment_type				2
Other-than-temporary impairment loss, debt securities, available-for-sale				$ 0
Payments to acquire equity securities	$ 2,000,000
Advertising expense		$ 5,279,000	$ 5,936,000	59,357,000	$ 29,167,000
Advertising production costs		17,000	$ 7,000	166,000	$ 20,000
Operating lease, right-of-use asset		45,513,000		45,513,000
Operating lease, liability		$ 62,790,000		$ 62,790,000
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset							$ 33,953,000
Operating lease, liability							$ 49,395,000
Software development
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Finite-lived intangible assets, useful life				2 years		1 year

Segment Reporting and Revenue -

Segment Reporting and Revenue - Narrative (Details)	9 Months Ended
	Sep. 30, 2019segment
Segment Reporting [Abstract]
Number of operating segments	5
Number of reportable segments	2

Segment Reporting and Revenue_2

Segment Reporting and Revenue - Reconciliation of Operating Profit (Loss) from Segments to Consolidated (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	$ 238,683	$ 140,255	$ 546,605	$ 362,791
Cost of revenue	185,306	97,950	442,127	269,576
Gross profit	53,377	42,305	104,478	93,215
Operating expenses	45,941	39,016	176,913	124,643
Interest income	1,576	1,775	5,804	3,082
Interest expense	(2,274)	(1,610)	(6,564)	(1,610)
Other income, net	44	21	172	200
Net income (loss)	6,782	3,475	(73,023)	(29,756)
Operating Segments | Real estate services
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	154,126	126,265	392,862	332,047
Cost of revenue	100,048	83,274	284,447	236,775
Gross profit	54,078	42,991	108,415	95,272
Operating Segments | Properties
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	80,164	11,350	141,445	23,388
Cost of revenue	80,909	11,656	144,807	24,086
Gross profit	(745)	(306)	(3,362)	(698)
Other revenue
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	5,161	2,691	13,490	7,407
Cost of revenue	5,117	3,071	14,065	8,766
Gross profit	44	(380)	(575)	(1,359)
Intercompany eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Cost of revenue	(768)	(51)	(1,192)	(51)
Gross profit	0	0	0	0
Brokerage revenue | Operating Segments | Real estate services
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	146,096	118,809	372,809	312,306
Partner revenue | Operating Segments | Real estate services
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenue	$ 8,030	$ 7,456	$ 20,053	$ 19,741

Segment Reporting and Revenue_3

Segment Reporting and Revenue - Summary of Accrued Revenue (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Segment Reporting [Abstract]
Accrued revenue	$ 24,703		$ 13,411
Less: Allowance for doubtful accounts	(269)	$ (166)	(157)	$ (160)
Accrued revenue, net	$ 24,434		$ 13,254

Segment Reporting and Revenue_4

Segment Reporting and Revenue - Activity in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Allowance for doubtful accounts
Balance, beginning of period	$ 166	$ 160
Charges	128	23
Write-offs	(25)	(26)
Balance, end of period	$ 269	$ 157

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Jul. 23, 2018
Fair Value, Measurements, Recurring
Assets
Loans held for sale	$ 22,246	$ 4,913
Derivative asset	819	254
Total assets	322,053	430,943
Liabilities
Total liabilities	168	141
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Loans held for sale	0	0
Derivative asset	0	0
Total assets	198,172	425,776
Liabilities
Total liabilities	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Loans held for sale	22,246	4,913
Derivative asset	216	0
Total assets	123,278	4,913
Liabilities
Total liabilities	44	141
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Loans held for sale	0	0
Derivative asset	603	254
Total assets	603	254
Liabilities
Total liabilities	124	0
U.S. treasury securities | Fair Value, Measurements, Recurring
Assets
U.S. treasury securities	62,054
U.S. treasury securities	38,480
U.S. treasury securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
U.S. treasury securities	0
U.S. treasury securities	0
U.S. treasury securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
U.S. treasury securities	62,054
U.S. treasury securities	38,480
U.S. treasury securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
U.S. treasury securities	0
U.S. treasury securities	0
Forward sales commitments | Fair Value, Measurements, Recurring
Assets
Derivative asset	216
Liabilities
Derivative liability	44	141
Forward sales commitments | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Derivative asset	0
Liabilities
Derivative liability	0	0
Forward sales commitments | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Derivative asset	216
Liabilities
Derivative liability	44	141
Forward sales commitments | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Derivative asset	0
Liabilities
Derivative liability	0	0
Interest rate lock commitments | Fair Value, Measurements, Recurring
Assets
Derivative asset	603	254
Liabilities
Derivative liability	124
Interest rate lock commitments | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Derivative asset	0	0
Liabilities
Derivative liability	0
Interest rate lock commitments | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Derivative asset	0	0
Liabilities
Derivative liability	0
Interest rate lock commitments | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Derivative asset	603	254
Liabilities
Derivative liability	124
Money market funds | Fair Value, Measurements, Recurring
Assets
Money market funds	198,172	425,776
Money market funds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Money market funds	198,172	425,776
Money market funds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Money market funds	0	0
Money market funds | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Money market funds	0	$ 0
U.S. treasury securities | Fair Value, Measurements, Recurring
Assets
U.S. treasury securities	282
U.S. treasury securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
U.S. treasury securities	0
U.S. treasury securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
U.S. treasury securities	282
U.S. treasury securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
U.S. treasury securities	$ 0
1.75% Convertible Senior Notes due 2023
Liabilities
Stated interest rate	1.75%		1.75%

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Properties for sale		$ 62,911	$ 12,649
Properties not available for sale		6,653	2,328
Properties under improvement		35,896	7,717
Inventory	$ 105,460	105,460	22,694
Lower of cost or net realizable value write-downs		$ 272	$ 190
Inventory, Current [Roll Forward]
Inventory as of December 31, 2018	22,694
Purchases and additions to inventory	213,813
Relief of inventory to cost of revenue	(130,965)
Lower of cost or net realizable value write-downs, net	(82)
Inventory as of September 30, 2019	$ 105,460

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 64,287	$ 46,717
Accumulated depreciation and amortization	(26,727)	(21,530)
Property and equipment, net	37,560	25,187
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	26,441	19,285
Website and software development costs
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 25,629	19,948
Website and software development costs | Minimum
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	2 years
Website and software development costs | Maximum
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	3 years
Computer and office equipment
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	3 years
Property and equipment, gross	$ 5,010	2,956
Software
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	3 years
Property and equipment, gross	$ 595	595
Furniture
Property, Plant and Equipment [Line Items]
Useful Lives (Years)	7 years
Property and equipment, gross	$ 6,612	$ 3,933

Property and Equipment - Narrat

Property and Equipment - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Depreciation and Amortization	$ 2,453	$ 2,099	$ 6,018	$ 5,757

Leases - Narrative (Details)

Leases - Narrative (Details)	Sep. 30, 2019
Minimum
Lessee, Lease, Description [Line Items]
Operating lease term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease term	11 years

Leases - Summary of Lease Cost

Leases - Summary of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Total lease cost	$ 2,894	$ 8,389
Short-term lease cost	399	1,889
Cost of revenue
Lessee, Lease, Description [Line Items]
Total lease cost	2,029	5,814
Operating expenses
Lessee, Lease, Description [Line Items]
Total lease cost	$ 865	$ 2,575

Leases - Maturity of Lease Liab

Leases - Maturity of Lease Liabilities (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Leases [Abstract]
2019, excluding the nine months ended September 30, 2019	$ 2,013
2020	14,437
2021	14,111
2022	13,409
2023	12,533
Thereafter	27,757
Total lease payments	84,260
Less: Interest and other	(21,470)
Present value of lease liabilities	62,790
Operating lease, capitalized interest expense	$ 9,050

Leases - Lease Term and Discoun

Leases - Lease Term and Discount Rate (Details)	Sep. 30, 2019
Leases [Abstract]
Weighted average remaining operating lease term (years)	6 years 1 month 6 days
Weighted average discount rate for operating leases	4.40%

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 7,040
Operating leases	$ 50,263

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details)	Sep. 30, 2019
Minimum
Debt Instrument [Line Items]
Operating lease term	1 year
Maximum
Debt Instrument [Line Items]
Operating lease term	11 years

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Future Minimum Payments (Details) $ in Thousands	Sep. 30, 2019USD ($)
Facility Leases
2019, excluding the nine months ended September 30, 2019	$ 2,013
2020	14,437
2021	14,111
2022	13,409
2023 and thereafter	40,290
Total lease payments	84,260
Other Commitments
2019, excluding the nine months ended September 30, 2019	26,796
2020	3,726
2021	1,173
2022	1,138
2023 and thereafter	0
Total minimum lease payments	$ 32,833

Acquired Intangible Assets - Sc

Acquired Intangible Assets - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross	$ 4,880	$ 4,880
Accumulated Amortization	(2,440)	(2,074)
Net	$ 2,440	2,806
Trade names
Finite-Lived Intangible Assets [Line Items]
Useful Lives (Years)	10 years
Gross	$ 1,040	1,040
Accumulated Amortization	(520)	(442)
Net	$ 520	598
Developed technology
Finite-Lived Intangible Assets [Line Items]
Useful Lives (Years)	10 years
Gross	$ 2,980	2,980
Accumulated Amortization	(1,490)	(1,266)
Net	$ 1,490	1,714
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful Lives (Years)	10 years
Gross	$ 860	860
Accumulated Amortization	(430)	(366)
Net	$ 430	$ 494

Acquired Intangible Assets - Na

Acquired Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization	$ 122	$ 122	$ 366	$ 244
Net	2,440		2,440
2019	488		488
2020	488		488
2021	488		488
2022	488		488
2023	$ 488		$ 488

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 40,234	$ 22,862
Miscellaneous accrued liabilities	10,633	7,975
Total accrued liabilities	$ 50,867	$ 30,837

Other Payables (Details)

Other Payables (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Customer deposits	$ 6,863	$ 6,226
Miscellaneous payables	294	318
Total other payables	$ 7,157	$ 6,544

Equity and Employee Stock Pla_3

Equity and Employee Stock Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Jun. 01, 2019	Jul. 27, 2017	Jul. 26, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, authorized (in shares)				500,000,000		500,000,000		500,000,000
Common stock, par value (in dollars per share)				$ 0.001		$ 0.001		$ 0.001
Preferred stock, shares authorized (in shares)				10,000,000		10,000,000		10,000,000
Preferred stock, par value (in dollars per share)				$ 0.001		$ 0.001		$ 0.001
Preferred stock, shares outstanding (in shares)				0		0		0
Preferred stock, shares issued (in shares)				0		0		0
Unrecognized stock-based compensation, options				$ 4,092		$ 4,092
Options granted (in shares)						150,000
Options granted (in dollars per share)						$ 27.50
Share-based payment expense				$ 7,510	$ 5,498	$ 19,792	$ 14,473
Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)			7,898,159	20,476,766		20,476,766		17,768,064
Percentage of common stock, outstanding			5.00%
Restricted stock units outstanding (in shares)				4,536,677		4,536,677		3,264,702
2017 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)				2,628,863		2,628,863		1,989,460
Shares issued under ESPP (in shares)				262,110		262,110
Employee stock purchase plan shares | 2004 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)				0		0
Employee stock purchase plan shares | 2017 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved (in shares)		1,600,000
Percentage of common stock, outstanding		1.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, period for recognition						1 year 3 months
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, period for recognition						3 years 29 days
Unrecognized stock-based compensation				$ 76,009		$ 76,009
Restricted stock units granted (in shares)						2,102,975
Restricted stock units outstanding (in shares)				4,536,677		4,536,677		3,264,702
Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units outstanding (in shares)				279,826		279,826
Achievement percentage of performance conditions						100.00%
Share-based payment expense						$ (126)
Chief Executive Officer | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	150,000
Options granted (in dollars per share)	$ 27.50
Maximum | Chief Executive Officer | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	300,000
January to December 2019 Awards | Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment expense						(610)
January to June 2019 Awards | Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment expense						$ 484

Equity and Employee Stock Pla_4

Equity and Employee Stock Plans - Summary of Common Stock Reserved for Future Issuance (in shares) (Details) - shares	Sep. 30, 2019	Dec. 31, 2018	Jul. 26, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares underlying outstanding stock options (in shares)	8,102,171	9,435,349
Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares underlying outstanding stock options (in shares)	8,102,171	9,435,349
Shares underlying outstanding restricted stock units (in shares)	4,536,677	3,264,702
Shares available for future equity grants (in shares)	7,837,918	5,068,013
Common stock reserved (in shares)	20,476,766	17,768,064	7,898,159
2017 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance on January 1, 2019 and 2018, respectively (in shares)	2,890,973	2,414,688
Shares issued since January 1, 2019 and 2018, respectively (in shares)	(262,110)	(425,228)
Common stock reserved (in shares)	2,628,863	1,989,460

Equity and Employee Stock Pla_5

Equity and Employee Stock Plans - Schedule of Stock Option Activity (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Number Of Options
Outstanding, beginning balance (in shares) | shares	9,435,349
Options granted (in shares) | shares	150,000
Options exercised (in shares) | shares	(1,397,074)
Options forfeited (in shares) | shares	(81,826)
Options canceled (in shares) | shares	(4,278)
Outstanding, ending balance (in shares) | shares	8,102,171	9,435,349
Options exercisable at period end (in shares) | shares	7,100,240
Weighted- Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 6.48
Options granted (in dollars per share) | $ / shares	27.50
Options exercised (in dollars per share) | $ / shares	5.49
Options forfeited (in dollars per share) | $ / shares	9.16
Options canceled (in dollars per share) | $ / shares	8.22
Outstanding, ending balance (in dollars per share) | $ / shares	7.01	$ 6.48
Options exercisable at period end (in dollars per share) | $ / shares	$ 6.30
Weighted-Average Remaining Contractual Life (Years)
Weighted average remaining contractual life outstanding	5 years 7 months 2 days	6 years 21 days
Weighted average remaining contractual life exercisable	5 years 3 months 25 days
Aggregate Intrinsic Value
Options outstanding, Aggregate intrinsic value | $	$ 81,204	$ 74,669
Options exercisable, Aggregate intrinsic value | $	$ 74,839

Equity and Employee Stock Pla_6

Equity and Employee Stock Plans - Schedule of Restricted Stock Unit Activity (Details) - Restricted stock units	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Restricted Stock Units
Unvested outstanding at beginning of period (in shares) | shares	3,264,702
Granted (in shares) | shares	2,102,975
Vested (in shares) | shares	(562,755)
Forfeited or canceled (in shares) | shares	(268,245)
Unvested outstanding at end of period (in shares) | shares	4,536,677
Weighted-Average Grant Date Fair Value
Unvested outstanding at beginning of period (in dollars per share) | $ / shares	$ 19.68
Granted (in dollars per share) | $ / shares	17.79
Vested (in dollars per share) | $ / shares	21
Forfeited or canceled (in dollars per share) | $ / shares	20.06
Unvested outstanding at end of period (in dollars per share) | $ / shares	$ 18.62

Equity and Employee Stock Pla_7

Equity and Employee Stock Plans - Allocation of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 7,510	$ 5,498	$ 19,792	$ 14,473
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,605	1,370	4,398	4,061
Technology and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	3,320	2,135	8,661	5,335
Marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	390	155	1,025	431
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 2,195	$ 1,838	$ 5,708	$ 4,646

Net Income (Loss) per Share - C

Net Income (Loss) per Share - Computation of Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator
Net income (loss)	$ 6,782	$ 3,475	$ (73,023)	$ (29,756)
Weighted average shares:
Basic (in shares)	91,994,731	87,743,223	91,279,086	84,327,266
Dilutive shares from stock plans (in shares)	5,176,539	6,899,240	0	0
Dilutive (in shares)	97,171,270	94,642,463	91,279,086	84,327,266
Net income (loss) per share
Net income (loss) per share - basic (in dollars per share)	$ 0.07	$ 0.04	$ (0.80)	$ (0.35)
Net income (loss) per share - diluted (in dollars per share)	$ 0.07	$ 0.04	$ (0.80)	$ (0.35)

Net Income (Loss) per Share - S

Net Income (Loss) per Share - Summary of Anti-dilutive Stock Equivalents (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	1,744,366	238,668	12,922,524	12,466,311
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	0	0	8,102,171	10,150,522
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	1,744,366	238,668	4,536,677	2,081,173
Employee stock purchase plan shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	0	0	283,676	234,616
Convertible Debt Securities
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from earnings per share (in shares)	0		0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Effective tax rate	0.00%	0.00%
Operating loss unavailable for carryforward				$ 1,538
Federal Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards			$ 125,850
Operating loss carryforwards, not subject to expiration			39,365
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards			$ 6,180

Debt - Warehouse Lines of Credi

Debt - Warehouse Lines of Credit (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Borrowings under warehouse credit facilities	$ 21,987,000	$ 4,733,000
Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Borrowing Capacity as of June 30, 2019	49,000,000
Borrowings under warehouse credit facilities	21,987,000	4,733,000
Western Alliance Bank | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Borrowing Capacity as of June 30, 2019	24,500,000
Borrowings under warehouse credit facilities	11,522,000	1,141,000
Texas Capital Bank, N.A. | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Borrowing Capacity as of June 30, 2019	24,500,000
Borrowings under warehouse credit facilities	$ 10,465,000	$ 3,592,000

Debt - Secured Revolving Credit

Debt - Secured Revolving Credit Facility (Details) - Goldman Sachs Bank USA - Revolving Credit Facility	Sep. 30, 2019USD ($)
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 100,000,000
Line of Credit Facility, Borrowings	$ 0

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jul. 23, 2018
1.75% Convertible Senior Notes due 2023
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 182,000	$ 131,000	$ 541,000	$ 131,000
Stated interest rate	1.75%		1.75%			1.75%
Aggregated principal amount						$ 143,750,000
Debt instrument, interest rate, effective percentage						7.25%
Significant Other Observable Inputs (Level 2) | 1.75% Convertible Senior Notes due 2023
Debt Instrument [Line Items]
Debt instrument, fair value	$ 131,028,000		$ 131,028,000		$ 117,875,000
Western Alliance Bank | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Stated interest rate	3.50%		3.50%
Western Alliance Bank | Warehouse Agreement Borrowings | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			2.00%
Texas Capital Bank, N.A. | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Stated interest rate	3.50%		3.50%
Decrease in rate of interest accruing on outstanding principal			0.50%
Goldman Sachs Bank USA | Revolving Credit Facility
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 102,000
Minimum | Goldman Sachs Bank USA | Revolving Credit Facility
Debt Instrument [Line Items]
LIBOR floor			0.50%
Maximum | Goldman Sachs Bank USA | Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			2.65%

Debt - Components of The Notes

Debt - Components of The Notes (Details) - 1.75% Convertible Senior Notes due 2023 - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Principal	$ 143,750	$ 143,750
Less: debt discount, net of amortization	(22,605)	(26,636)
Less: debt issuance costs, net of amortization	(2,987)	(3,528)
Net carrying amount of the Notes	$ 118,158	$ 113,586

Debt - Interest Expense (Detail

Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jul. 23, 2018
Debt Instrument [Line Items]
Total amortization of debt issuance costs and accretion of equity portion			$ 4,674	$ 1,128
Total interest expense related to the Notes	$ 2,274	$ 1,610	6,564	1,610
1.75% Convertible Senior Notes due 2023
Debt Instrument [Line Items]
Amortization of debt discount	1,359	997	4,031	997
Amortization of debt issuance costs	182	131	541	131
Total amortization of debt issuance costs and accretion of equity portion	1,541	1,128	4,572	1,128
Contractual interest expense	629	482	1,887	482
Total interest expense related to the Notes	$ 2,170	$ 1,610	$ 6,459	$ 1,610
Effective interest rate of the liability component					7.25%

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - Line of Credit - Revolving Credit Facility - Flagstar Warehouse Credit Facility	1 Months Ended
	Oct. 31, 2019USD ($)
Subsequent Event [Line Items]
Line of credit facility, maximum borrowing capacity	$ 15,000
Stated interest rate	3.00%
London Interbank Offered Rate (LIBOR)
Subsequent Event [Line Items]
Debt instrument, basis spread on variable rate	2.00%