Zillow (Z) 10-Q 7 Nov 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-36853
Entity Registrant Name	ZILLOW GROUP, INC.
Entity Central Index Key	0001617640
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Incorporation, State or Country Code	WA
Entity Tax Identification Number	47-1645716
Entity Address, Address Line One	1301 Second Avenue
Entity Address, Address Line Two	Floor 31
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	470-7000
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
Class A Common Stock
Entity Information [Line Items]
Title of 12(b) Security	Class A Common Stock, par value $0.0001 per share
Trading Symbol	ZG
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		58,524,004
Class B Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		6,217,447
Class C Capital Stock
Entity Information [Line Items]
Title of 12(b) Security	Class C Capital Stock, par value $0.0001 per share
Trading Symbol	Z
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		142,711,993

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 1,791,918	$ 651,058
Short-term investments	531,679	903,867
Accounts receivable, net of allowance for doubtful accounts of $4,464 and $4,838 at September 30, 2019 and December 31, 2018, respectively	77,674	66,083
Mortgage loans held for sale	36,762	35,409
Inventory	879,353	162,829
Prepaid expenses and other current assets	66,413	61,067
Restricted cash	75,004	12,385
Total current assets	3,458,803	1,892,698
Contract cost assets	46,047	45,819
Property and equipment, net	154,251	135,172
Right of use assets	218,564
Goodwill	1,984,907	1,984,907
Intangible assets, net	197,527	215,904
Other assets	15,889	16,616
Total assets	6,075,988	4,291,116
Current liabilities:
Accounts payable	9,717	7,471
Accrued expenses and other current liabilities	76,061	63,101
Accrued compensation and benefits	33,540	31,388
Revolving credit facilities	698,280	116,700
Warehouse lines of credit	30,116	33,018
Deferred revenue	41,955	34,080
Deferred rent, current portion		1,740
Lease liabilities, current portion	17,937
Total current liabilities	907,606	287,498
Deferred rent, net of current portion		19,945
Lease liabilities, net of current portion	223,989
Long-term debt	1,478,719	699,020
Deferred tax liabilities and other long-term liabilities	13,796	17,474
Total liabilities	2,624,110	1,023,937
Commitments and contingencies (Note 17)
Shareholders’ equity:
Preferred stock, $0.0001 par value; 30,000,000 shares authorized; no shares issued and outstanding	0	0
Additional paid-in capital	4,327,003	3,939,842
Accumulated other comprehensive income (loss)	784	(905)
Accumulated deficit	(875,930)	(671,779)
Total shareholders’ equity	3,451,878	3,267,179
Total liabilities and shareholders’ equity	6,075,988	4,291,116
Class A Common Stock
Shareholders’ equity:
Common stock/capital stock	6	6
Class B Common Stock
Shareholders’ equity:
Common stock/capital stock	1	1
Class C Capital Stock
Shareholders’ equity:
Common stock/capital stock	$ 14	$ 14

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Allowance for doubtful accounts	$ 4,464	$ 4,838
Preferred stock, par value (usd per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	30,000,000	30,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Class A Common Stock
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	1,245,000,000	1,245,000,000
Common stock, issued (in shares)	58,522,404	58,051,448
Common stock, outstanding (in shares)	58,522,404	58,051,448
Class B Common Stock
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	15,000,000	15,000,000
Common stock, issued (in shares)	6,217,447	6,217,447
Common stock, outstanding (in shares)	6,217,447	6,217,447
Class C Capital Stock
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	600,000,000	600,000,000
Common stock, issued (in shares)	142,689,395	139,635,370
Common stock, outstanding (in shares)	142,689,395	139,635,370

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Revenue		$ 745,208	$ 343,094	$ 1,798,890	$ 968,219
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	399,835	36,672	822,404	86,118
Sales and marketing		181,347	128,734	530,367	413,752
Technology and development		123,974	105,314	352,074	299,623
General and administrative		88,493	70,743	267,106	187,395
Impairment costs		0	10,000	0	10,000
Acquisition-related costs		0	1,405	0	2,064
Integration costs		5	523	650	523
Total costs and expenses		793,654	353,391	1,972,601	999,475
Loss from operations		(48,446)	(10,297)	(173,711)	(31,256)
Other income		8,999	7,773	27,625	13,308
Interest expense		(26,502)	(12,668)	(61,865)	(26,928)
Loss before income taxes		(65,949)	(15,192)	(207,951)	(44,876)
Income tax benefit		1,300	14,700	3,800	22,700
Net loss		$ (64,649)	$ (492)	$ (204,151)	$ (22,176)
Net loss per share - basic and diluted (usd per share)		$ (0.31)	$ 0	$ (0.99)	$ (0.11)
Weighted-average shares outstanding - basic and diluted (in shares)		207,002	202,416	205,766	195,208
Amortization of website development costs and intangible assets included in technology and development		$ 11,100	$ 12,000	$ 33,100	$ 37,600
Technology and Development
Cost of revenue (exclusive of amortization)
Amortization of website development costs and intangible assets included in technology and development		15,835	18,165	44,891	61,735
Homes
Revenue:
Revenue		384,626	11,018	762,022	11,018
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	370,796	10,226	733,947	10,312
Sales and marketing		49,186	4,650	107,457	7,035
Technology and development		20,651	6,128	51,130	12,154
General and administrative		22,174	6,010	54,339	11,964
Impairment costs		0	0	0	0
Acquisition-related costs		0	0	0	0
Integration costs		0	0	0	0
Total costs and expenses		462,807	27,014	946,873	41,465
Loss from operations		(78,181)	(15,996)	(184,851)	(30,447)
Other income		0	0	0	0
Interest expense		(9,689)	(432)	(19,346)	(432)
Loss before income taxes		(87,870)	(16,428)	(204,197)	(30,879)
IMT
Revenue:
Revenue		335,290	313,638	957,231	900,435
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	24,318	25,186	74,628	72,070
Sales and marketing		118,514	117,522	380,608	384,241
Technology and development		94,656	93,930	276,886	270,978
General and administrative		55,749	60,678	181,270	163,303
Impairment costs		0	10,000	0	10,000
Acquisition-related costs		0	0	0	27
Integration costs		0	0	0	0
Total costs and expenses		293,237	307,316	913,392	900,619
Loss from operations		42,053	6,322	43,839	(184)
Other income		0	0	0	0
Interest expense		0	0	0	0
Loss before income taxes		42,053	6,322	43,839	(184)
Mortgages
Revenue:
Revenue		25,292	18,438	79,637	56,766
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	4,721	1,260	13,829	3,736
Sales and marketing		13,647	6,562	42,302	22,476
Technology and development		8,667	5,256	24,058	16,491
General and administrative		10,570	4,055	31,497	12,128
Impairment costs		0	0	0	0
Acquisition-related costs		0	1,405	0	2,037
Integration costs		5	523	650	523
Total costs and expenses		37,610	19,061	112,336	57,391
Loss from operations		(12,318)	(623)	(32,699)	(625)
Other income		344	0	1,059	0
Interest expense		(280)	0	(668)	0
Loss before income taxes		$ (12,254)	$ (623)	$ (32,308)	$ (625)
[1]	Amortization of website development costs and intangible assets included in technology and development of $15,835 and $18,165 for the three months ended September 30, 2019 and 2018, respectively and $44,891 and $61,735 for the nine months ended September 30, 2019 and 2018, respectively.

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (64,649)	$ (492)	$ (204,151)	$ (22,176)
Other comprehensive income (loss):
Unrealized gains (losses) on investments	(143)	(428)	1,752	(537)
Currency translation adjustments	31	42	(63)	(24)
Total other comprehensive income (loss)	(112)	(386)	1,689	(561)
Comprehensive loss	$ (64,761)	$ (878)	$ (202,462)	$ (22,737)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Class A Common Stock, Class B Common Stock and Class C Capital Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2017	$ 2,660,823	$ 20	$ 3,254,146	$ (592,243)	$ (1,100)
Beginning Balance (in shares) at Dec. 31, 2017		190,115,148,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	114,623		114,623
Issuance of common and capital stock upon exercise of stock options (in shares)		5,177,060,000
Vesting of restricted stock units	0
Vesting of restricted stock units (in shares)		1,288,746,000
Shares and value of restricted stock units withheld for tax liability	(67)		(67)
Shares and value of restricted stock units withheld for tax liability (in shares)		(1,345,000)
Share-based compensation expense	118,037		118,037
Portion of conversion recorded in additional paid-in-capital in connection with partial conversion of convertible notes maturing in 2020	500		500
Portion of conversion recorded in additional paid-in-capital in connection with partial conversion of convertible notes maturing in 2020 (in shares)		20,727,000
Issuance of Class C capital stock in connection with equity offering, net of issuance costs	360,345	$ 0	360,345
Issuance of Class C capital stock in connection with equity offering, net of issuance costs (in shares)		6,557,017,000
Premiums paid for capped call confirmations	(29,414)		(29,414)
Equity component of issuance of convertible notes, net of issuance costs	76,587		76,587
Net loss	(22,176)			(22,176)
Other comprehensive income (loss)	(561)				(561)
Ending Balance at Sep. 30, 2018	3,319,019	$ 20	3,894,757	(574,097)	(1,661)
Ending Balance (in shares) at Sep. 30, 2018		203,157,353,000
Beginning Balance at Jun. 30, 2018	2,853,681	$ 20	3,428,541	(573,605)	(1,275)
Beginning Balance (in shares) at Jun. 30, 2018		195,449,104,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	14,970		14,970
Issuance of common and capital stock upon exercise of stock options (in shares)		697,301,000
Vesting of restricted stock units	0
Vesting of restricted stock units (in shares)		453,958,000
Shares and value of restricted stock units withheld for tax liability	(2)		(2)
Shares and value of restricted stock units withheld for tax liability (in shares)		(27,000)
Share-based compensation expense	43,730		43,730
Issuance of Class C capital stock in connection with equity offering, net of issuance costs	360,345	$ 0	360,345
Issuance of Class C capital stock in connection with equity offering, net of issuance costs (in shares)		6,557,017,000
Premiums paid for capped call confirmations	(29,414)		(29,414)
Equity component of issuance of convertible notes, net of issuance costs	76,587		76,587
Net loss	(492)			(492)
Other comprehensive income (loss)	(386)				(386)
Ending Balance at Sep. 30, 2018	3,319,019	$ 20	3,894,757	(574,097)	(1,661)
Ending Balance (in shares) at Sep. 30, 2018		203,157,353,000
Beginning Balance at Dec. 31, 2018	3,267,179	$ 21	3,939,842	(671,779)	(905)
Beginning Balance (in shares) at Dec. 31, 2018		203,904,265,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	$ 41,014		41,014
Issuance of common and capital stock upon exercise of stock options (in shares)	1,891,111	1,891,111,000
Vesting of restricted stock units	$ 0
Vesting of restricted stock units (in shares)		1,633,962,000
Shares and value of restricted stock units withheld for tax liability	(3)		(3)
Shares and value of restricted stock units withheld for tax liability (in shares)		(92,000)
Share-based compensation expense	160,826		160,826
Premiums paid for capped call confirmations	(150,530)		(150,530)
Equity component of issuance of convertible notes, net of issuance costs	335,854		335,854
Net loss	(204,151)			(204,151)
Other comprehensive income (loss)	1,689				1,689
Ending Balance at Sep. 30, 2019	3,451,878	$ 21	4,327,003	(875,930)	784
Ending Balance (in shares) at Sep. 30, 2019		207,429,246,000
Beginning Balance at Jun. 30, 2019	3,278,106	$ 21	4,088,470	(811,281)	896
Beginning Balance (in shares) at Jun. 30, 2019		206,513,636,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	8,017		8,017
Issuance of common and capital stock upon exercise of stock options (in shares)		347,261,000
Vesting of restricted stock units	0
Vesting of restricted stock units (in shares)		568,355,000
Shares and value of restricted stock units withheld for tax liability	0		0
Shares and value of restricted stock units withheld for tax liability (in shares)		(6,000)
Share-based compensation expense	45,192		45,192
Premiums paid for capped call confirmations	(150,530)		(150,530)
Equity component of issuance of convertible notes, net of issuance costs	335,854		335,854
Net loss	(64,649)			(64,649)
Other comprehensive income (loss)	(112)				(112)
Ending Balance at Sep. 30, 2019	$ 3,451,878	$ 21	$ 4,327,003	$ (875,930)	$ 784
Ending Balance (in shares) at Sep. 30, 2019		207,429,246,000

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2019
Statement of Stockholders' Equity [Abstract]
Senior notes, issuance costs	$ 2,047	$ 2,047	$ 4,430
Capital stock, issuance costs	$ 13,425	$ 13,425

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net loss	$ (204,151)	$ (22,176)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	63,888	76,301
Share-based compensation expense	151,884	111,366
Amortization of right of use assets	16,710
Amortization of contract cost assets	26,722	27,227
Amortization of discount and issuance costs on convertible senior notes maturing in 2021, 2023, 2024 and 2026	29,868	17,990
Impairment costs	0	10,000
Deferred income taxes	(3,800)	(22,700)
Loss on disposal of property and equipment	5,744	3,129
Bad debt expense	1,894	1,053
Deferred rent	0	(3,116)
Accretion of bond discount	(5,241)	(2,172)
Changes in operating assets and liabilities:
Accounts receivable	(13,485)	(12,994)
Mortgage loans held for sale	(1,353)	0
Inventory	(716,524)	(43,257)
Prepaid expenses and other assets	(5,848)	(15,012)
Lease liabilities	(15,029)
Contract cost assets	(26,950)	(32,143)
Accounts payable	2,999	2,254
Accrued expenses and other current liabilities	12,241	(3,751)
Accrued compensation and benefits	2,152	6,503
Deferred revenue	7,875	4,041
Other long-term liabilities	122	0
Net cash provided by (used in) operating activities	(670,282)	102,543
Investing activities
Proceeds from maturities of investments	859,142	261,675
Purchases of investments	(479,963)	(848,838)
Purchases of property and equipment	(45,140)	(44,482)
Purchases of intangible assets	(15,123)	(8,179)
Cash paid for acquisition, net	0	(2,000)
Net cash provided by (used in) investing activities	318,916	(641,824)
Financing activities
Proceeds from issuance of convertible notes, net of issuance costs	1,085,686	364,020
Premiums paid for capped call confirmations	(150,530)	(29,414)
Proceeds from issuance of Class C capital stock, net of issuance costs	0	360,345
Proceeds from borrowing on revolving credit facilities	581,580	24,674
Net repayments on warehouse lines of credit	(2,902)	0
Proceeds from exercise of stock options	41,014	114,623
Value of equity awards withheld for tax liability	(3)	(67)
Net cash provided by financing activities	1,554,845	834,181
Net increase in cash, cash equivalents and restricted cash during period	1,203,479	294,900
Cash, cash equivalents and restricted cash at beginning of period	663,443	352,095
Cash, cash equivalents and restricted cash at end of period	1,866,922	646,995
Supplemental disclosures of cash flow information
Cash paid for interest	25,837	4,800
Noncash transactions:
Capitalized share-based compensation	8,942	6,674
Write-off of fully depreciated property and equipment	28,951	18,687
Write-off of fully amortized intangible assets	$ 9,959	$ 10,797

Organization and Description of

Organization and Description of Business	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Organization and Description of Business	Organization and Description of Business Zillow Group, Inc. houses one of the largest portfolios of real estate brands on mobile and the web. Zillow Group is committed to leveraging its proprietary data, technology and innovations to make home buying, selling, financing and renting a seamless, on-demand experience for consumers. As its flagship brand, Zillow now offers a fully integrated home shopping experience that includes access to for sale and rental listings, Zillow Offers, which provides a new, hassle-free way to buy and sell homes directly through Zillow, and Zillow Home Loans, Zillow’s affiliated lender that provides an easy way to receive mortgage pre-approvals and financing. Other consumer brands include Trulia, StreetEasy, HotPads, Naked Apartments and Out East. In addition, Zillow Group provides a comprehensive suite of marketing software and technology solutions to help real estate professionals maximize business opportunities and connect with millions of consumers. Zillow Group also operates a number of business brands for real estate, rental and mortgage professionals, including Mortech, dotloop, Bridge Interactive and New Home Feed. Zillow, Inc. was incorporated as a Washington corporation in December 2004, and we launched the initial version of our website, Zillow.com, in February 2006. Zillow Group, Inc. was incorporated as a Washington corporation in July 2014 in connection with our acquisition of Trulia, Inc. (“Trulia”). Upon the closing of the Trulia acquisition in February 2015, each of Zillow, Inc. and Trulia became wholly owned subsidiaries of Zillow Group. Certain Significant Risks and Uncertainties We operate in a dynamic industry and, accordingly, can be affected by a variety of factors. For example, we believe that changes in any of the following areas could have a significant negative effect on us in terms of our future financial position, results of operations or cash flows: rates of revenue growth; our ability to manage advertising inventory or pricing; engagement and usage of our products; our investment of resources to pursue strategies that may not prove effective; competition in our market; the stability of the residential real estate market and the impact of interest rate changes; changes in technology, products, markets or services by us or our competitors; addition or loss of significant customers; our ability to maintain or establish relationships with listings and data providers; our ability to obtain or maintain licenses and permits to support our current and future businesses; changes in government regulation affecting our business; outcomes of legal proceedings; natural disasters and catastrophic events; scaling and adaptation of existing technology and network infrastructure; management of our growth; our ability to attract and retain qualified employees and key personnel; our ability to successfully integrate and realize the benefits of our past or future strategic acquisitions or investments; protection of customers’ information and other privacy concerns; protection of our brand and intellectual property; and intellectual property infringement and other claims, among other things.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements include Zillow Group, Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and accompanying notes included in Zillow Group, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2018 , which was filed with the SEC on February 21, 2019. The condensed consolidated balance sheet as of December 31, 2018 , included herein, was derived from the audited financial statements of Zillow Group, Inc. as of that date. The unaudited condensed consolidated interim financial statements, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly our financial position as of September 30, 2019 , our results of operations, comprehensive loss and shareholders’ equity for the three and nine month periods ended September 30, 2019 and 2018 , and our cash flows for the nine month periods ended September 30, 2019 and 2018 . The results of the three and nine month periods 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. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenue and expenses during the periods presented. On an ongoing basis, we evaluate our estimates, including those related to the net realizable value of inventory, amortization period and recoverability of contract cost assets, website and software development costs, recoverability of long-lived assets and intangible assets with definite lives, share-based compensation, income taxes, business combinations and the recoverability of goodwill and indefinite-lived intangible assets, among others. To the extent there are material differences between these estimates, judgments or assumptions and actual results, our financial statements will be affected. Recently Issued Accounting Standards Not Yet Adopted In August 2018, the Financial Accounting Standards Board (“FASB”) issued guidance related to a customer’s accounting for implementation costs incurred in hosting arrangements. The guidance conforms the requirements for capitalizing implementation costs incurred in cloud computing arrangements that are service contracts with the accounting guidance that provides for the capitalization of costs incurred to develop or obtain internal-use software. Under the guidance, implementation costs that are capitalized should be characterized in financial statements in the same manner as other service costs and assets related to service costs and amortized over the term of the hosting arrangement. This guidance is effective for interim and annual reporting periods beginning after December 15, 2019, and early adoption is permitted. Entities are permitted to apply either a retrospective or prospective transition approach to adopt this guidance. We expect to adopt this guidance on January 1, 2020 using the prospective transition approach, under which we will apply the guidance to all eligible costs incurred subsequent to adoption. We have not historically incurred material amounts of implementation costs for cloud computing arrangements, however, we are continuing to assess the impact the adoption of this guidance will have on our financial position, results of operations and cash flows. In August 2018, the FASB issued guidance related to disclosure requirements for fair value measurements. This guidance removes, modifies and adds disclosures related to certain assets and liabilities measured at fair value. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim and annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. This guidance is effective for interim and annual periods beginning after December 15, 2019, and early adoption is permitted. We expect to adopt this guidance on January 1, 2020. We have not historically recorded material amounts of Level 3 assets and liabilities or material transfers of assets or liabilities between levels within the fair value hierarchy. However, we are continuing to assess the impact the adoption of this guidance will have on our financial statement disclosures. In June 2016, and subsequently amended in April 2019 and May 2019, the FASB issued guidance on the measurement of credit losses on financial assets. This guidance will require an entity to measure and recognize expected credit losses for certain financial instruments and financial assets, including trade receivables. This guidance requires an entity to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument on initial recognition and at each reporting period, whereas current guidance employs an incurred loss methodology. This guidance is effective for interim and annual periods beginning after December 15, 2019, and early adoption is permitted for interim and annual reporting periods beginning after December 15, 2018. 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 adopted. We expect to adopt this guidance on January 1, 2020. We are currently evaluating necessary changes to our accounting policies, processes and systems as a result of the adoption of the guidance, primarily related to our trade accounts receivable and certain available-for-sale investments. We continue to assess the impact the adoption of this guidance will have on our financial position, results of operations and cash flows.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Accounting standards define fair value as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The standards also establish a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Assets and liabilities valued based on observable market data for similar instruments, such as quoted prices for similar assets or liabilities. • Level 3—Unobservable inputs that are supported by little or no market activity; instruments valued based on the best available data, some of which is internally developed, and considers risk premiums that a market participant would require. We applied the following methods and assumptions in estimating our fair value measurements: Cash equivalents — The fair value measurement of money market funds is based on quoted market prices in active markets. The fair value measurement of certificates of deposit and commercial paper is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means. Short-term investments — The fair value measurement of our short-term investments is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means. Restricted cash — Restricted cash consists of cash received from the resale of homes through Zillow Offers which may be used to repay amounts borrowed on our revolving credit facilities (see Note 13 ) and amounts held in escrow related to funding home purchases in our mortgage origination business. The carrying value of restricted cash approximates fair value due to the short period of time amounts borrowed on the revolving credit facilities are outstanding. Mortgage loans held for sale — The fair value of mortgage loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Interest rate lock commitments — The fair value of interest rate lock commitments (“IRLCs”) is calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Expired commitments are excluded from the fair value measurement. We generally only issue IRLCs for products that meet specific purchaser guidelines. Since not all IRLCs will become closed loans, we adjust our fair value measurements for the estimated amount of IRLCs that will not close. Forward contracts — The fair value of mandatory loan sales commitments and derivative instruments such as forward sales of mortgage-backed securities that are utilized as hedging instruments are calculated by reference to quoted prices for similar assets. The following tables present the balances of assets and liabilities measured at fair value on a recurring basis, by level within the fair value hierarchy, as of the dates presented (in thousands): September 30, 2019 Total Level 1 Level 2 Cash equivalents: Money market funds $ 1,353,600 $ 1,353,600 $ — Certificates of deposit 742 — 742 Short-term investments: U.S. government agency securities 350,665 — 350,665 Commercial paper 68,915 — 68,915 Corporate notes and bonds 63,585 — 63,585 Treasury bills 29,911 — 29,911 Municipal securities 18,603 — 18,603 Mortgage origination-related: Mortgage loans held for sale 36,762 — 36,762 IRLCs 1,503 — 1,503 Forward contracts - other current assets 84 — 84 Forward contracts - other current liabilities (184 ) — (184 ) Total $ 1,924,186 $ 1,353,600 $ 570,586 December 31, 2018 Total Level 1 Level 2 Cash equivalents: Money market funds $ 541,575 $ 541,575 $ — Commercial paper 3,999 — 3,999 Short-term investments: U.S. government agency securities 646,496 — 646,496 Corporate notes and bonds 112,933 — 112,933 Commercial paper 85,506 — 85,506 Municipal securities 39,306 — 39,306 Foreign government securities 14,915 — 14,915 Certificates of deposit 4,711 — 4,711 Mortgage origination-related: Mortgage loans held for sale 35,409 — 35,409 IRLCs 847 — 847 Forward contracts - other current liabilities (125 ) — (125 ) Total $ 1,485,572 $ 541,575 $ 943,997 At September 30, 2019 , the notional amounts of the hedging instruments related to our mortgage loans held for sale were $57.9 million and $99.8 million for our IRLCs and forward contracts, respectively. At December 31, 2018 , the notional amounts of the hedging instruments related to our mortgage loans held for sale were $26.7 million and $28.8 million for our IRLCs and forward contracts, respectively. We do not have the right to offset our forward contract derivative positions. See Note 13 for the carrying amount and estimated fair value of the Company’s convertible senior notes. We did no t have material Level 3 assets or liabilities as of September 30, 2019 or December 31, 2018

Cash and Cash Equivalents, Shor

Cash and Cash Equivalents, Short-term Investments and Restricted Cash	9 Months Ended
	Sep. 30, 2019
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents, Short-term Investments and Restricted Cash	Cash and Cash Equivalents, Short-term Investments and Restricted Cash The following tables present the amortized cost, gross unrealized gains and losses and estimated fair market value of our cash and cash equivalents, available-for-sale investments and restricted cash as of the dates presented (in thousands): September 30, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 437,576 $ — $ — $ 437,576 Cash equivalents: Money market funds 1,353,600 — — 1,353,600 Certificates of deposit 742 — — 742 Short-term investments: U.S. government agency securities 350,153 514 (2 ) 350,665 Commercial paper 68,915 — — 68,915 Corporate notes and bonds 63,419 166 — 63,585 Treasury bills 29,900 11 — 29,911 Municipal securities 18,511 92 — 18,603 Restricted cash 75,004 — — 75,004 Total $ 2,397,820 $ 783 $ (2 ) $ 2,398,601 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 105,484 $ — $ — $ 105,484 Cash equivalents: Money market funds 541,575 — — 541,575 Commercial paper 3,999 — — 3,999 Short-term investments: U.S. government agency securities 647,266 51 (821 ) 646,496 Corporate notes and bonds 113,109 1 (177 ) 112,933 Commercial paper 85,506 — — 85,506 Municipal securities 39,316 23 (33 ) 39,306 Foreign government securities 14,929 — (14 ) 14,915 Certificates of deposit 4,711 1 (1 ) 4,711 Restricted cash 12,385 — — 12,385 Total $ 1,568,280 $ 76 $ (1,046 ) $ 1,567,310 All available-for-sale investments as of September 30, 2019 have a contractual maturity date of one year or less.

Accounts Receivable, net

Accounts Receivable, net	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Accounts Receivable, net	Accounts Receivable, net The opening balance of accounts receivable, net was $66.1 million as of January 1, 2019. The following table presents the changes in the allowance for doubtful accounts (in thousands): Balance as of January 1, 2019 $ 4,838 Bad debt expense 1,894 Less: write-offs, net of recoveries and other adjustments (2,268 ) Balance as of September 30, 2019 $ 4,464

Inventory

Inventory	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Inventory	Inventory The following table presents the components of inventory, net of applicable lower of cost or net realizable value adjustments, as of the dates presented (in thousands): September 30, December 31, Work-in-process $ 196,295 $ 45,943 Finished goods 683,058 116,886 Inventory $ 879,353 $ 162,829

Contract Cost Assets

Contract Cost Assets	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Contract Cost Assets	Contract Cost Assets As of September 30, 2019 and December 31, 2018 , we had $46.0 million and $45.8 million , respectively, of contract cost assets. During the three and nine month periods ended September 30, 2019 and 2018 , we recorded no impairment losses. We recorded amortization expense related to contract cost assets of $8.8 million and $8.9 million during the three months ended September 30, 2019 and 2018 , respectively, and $26.7 million and $27.2 million during the nine months ended September 30, 2019 and 2018 , respectively. The following tables present the changes in deferred revenue for the periods presented (in thousands): Three Months Ended Balance as of July 1, 2019 $ 37,080 Deferral of revenue 300,715 Less: Revenue recognized (295,840 ) Balance as of September 30, 2019 $ 41,955 Nine Months Ended Balance as of January 1, 2019 $ 34,080 Deferral of revenue 802,699 Less: Revenue recognized (794,824 ) Balance as of September 30, 2019 $ 41,955 During the three months ended September 30, 2019 we recognized as revenue a total of $34.2 million pertaining to amounts that were recorded in deferred revenue as of July 1, 2019. During the nine months ended September 30, 2019 , we recognized as revenue a total of $31.5 million pertaining to amounts that were recorded in deferred revenue as of January 1, 2019.

Property and Equipment, net

Property and Equipment, net	9 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment, net	Property and Equipment, net The following table presents the detail of property and equipment as of the dates presented (in thousands): September 30, December 31, Website development costs $ 151,314 $ 149,891 Leasehold improvements 79,216 65,012 Office equipment, furniture and fixtures 34,801 39,510 Computer equipment 33,349 22,477 Construction-in-progress 26,519 29,037 Property and equipment 325,199 305,927 Less: accumulated amortization and depreciation (170,948 ) (170,755 ) Property and equipment, net $ 154,251 $ 135,172 We recorded depreciation expense related to property and equipment (other than website development costs) of $6.1 million and $5.1 million during the three months ended September 30, 2019 and 2018 , respectively, and $18.5 million and $14.2 million during the nine months ended September 30, 2019 and 2018 , respectively. We capitalized $10.8 million and $8.0 million in website development costs during the three months ended September 30, 2019 and 2018 , respectively, and $31.1 million and $26.6 million during the nine months ended September 30, 2019 and 2018 , respectively. Amortization expense for website development costs included in technology and development expenses was $4.8 million and $6.2 million during the three months ended September 30, 2019 and 2018 , respectively, and $11.8 million and $24.2 million during the nine months ended September 30, 2019 and 2018 , respectively.

Equity Investment

Equity Investment	9 Months Ended
	Sep. 30, 2019
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment	Equity Investment In October 2016, we purchased a 10% equity interest in a privately held variable interest entity within the real estate industry for $10.0 million . The entity is financed through its business operations. We are not the primary beneficiary of the entity, as we do not direct the activities that most significantly impact the entity’s economic performance. Therefore, we do not consolidate the entity. Our maximum exposure to loss is $10.0 million , the carrying amount of the investment as of September 30, 2019 . This investment is an equity security without a readily determinable fair value which we account 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. There has been no impairment or upward or downward adjustments to our equity investment as of September 30, 2019 that would impact the carrying amount of the investment. The equity investment is classified within other assets in the condensed consolidated balance sheet.

Intangible Assets, net

Intangible Assets, net	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets, net	Intangible Assets, net The following tables present the detail of intangible assets subject to amortization as of the dates presented (in thousands): September 30, 2019 Cost Accumulated Amortization Net Purchased content $ 45,542 $ (38,095 ) $ 7,447 Software 32,959 (18,577 ) 14,382 Customer relationships 103,300 (70,354 ) 32,946 Developed technology 107,200 (78,284 ) 28,916 Lender licenses 400 (167 ) 233 Intangibles-in-progress 5,603 — 5,603 Total $ 295,004 $ (205,477 ) $ 89,527 December 31, 2018 Cost Accumulated Amortization Net Purchased content $ 42,110 $ (30,477 ) $ 11,633 Software 24,296 (13,925 ) 10,371 Customer relationships 103,900 (60,733 ) 43,167 Developed technology 111,980 (72,788 ) 39,192 Trade names and trademarks 4,900 (4,683 ) 217 Lender licenses 400 (17 ) 383 Intangibles-in-progress 2,941 — 2,941 Total $ 290,527 $ (182,623 ) $ 107,904 Amortization expense recorded for intangible assets for the three months ended September 30, 2019 and 2018 was $11.1 million and $12.0 million , respectively. Amortization expense recorded for intangible assets for the nine months ended September 30, 2019 and 2018 was $33.1 million and $37.6 million , respectively. These amounts are included in technology and development expenses. We have an indefinite-lived intangible asset that we recorded in connection with our February 2015 acquisition of Trulia for Trulia’s trade names and trademarks that is not subject to amortization. The carrying value of the Trulia trade names and trademarks intangible asset was $108.0 million as of September 30, 2019 and December 31, 2018 . Intangibles-in-progress consists of software that is capitalizable but has not been placed in service.

Deferred Revenue

Deferred Revenue	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Deferred Revenue	Contract Cost Assets As of September 30, 2019 and December 31, 2018 , we had $46.0 million and $45.8 million , respectively, of contract cost assets. During the three and nine month periods ended September 30, 2019 and 2018 , we recorded no impairment losses. We recorded amortization expense related to contract cost assets of $8.8 million and $8.9 million during the three months ended September 30, 2019 and 2018 , respectively, and $26.7 million and $27.2 million during the nine months ended September 30, 2019 and 2018 , respectively. The following tables present the changes in deferred revenue for the periods presented (in thousands): Three Months Ended Balance as of July 1, 2019 $ 37,080 Deferral of revenue 300,715 Less: Revenue recognized (295,840 ) Balance as of September 30, 2019 $ 41,955 Nine Months Ended Balance as of January 1, 2019 $ 34,080 Deferral of revenue 802,699 Less: Revenue recognized (794,824 ) Balance as of September 30, 2019 $ 41,955 During the three months ended September 30, 2019 we recognized as revenue a total of $34.2 million pertaining to amounts that were recorded in deferred revenue as of July 1, 2019. During the nine months ended September 30, 2019 , we recognized as revenue a total of $31.5 million pertaining to amounts that were recorded in deferred revenue as of January 1, 2019.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases Our lease portfolio is primarily composed of operating leases for our office space. We have lease agreements that include lease components (e.g., fixed rent) and non-lease components (e.g., common area maintenance), which are accounted for as a single component, as we have elected the practical expedient to group lease and non-lease components. We also elected the practical expedient to keep leases with an initial term of 12 months or less off the balance sheet and recognize the associated lease payments in the condensed consolidated statements of operations on a straight-line basis over the lease term. Our leases have remaining lease terms ranging from less than one year to twelve years , some of which include options to extend the lease term for up to an additional ten years . For example, our largest leases, which include our corporate headquarters in Seattle, Washington and office space in New York, New York and San Francisco, California, include options to renew the existing leases for either one or two periods of five years . When determining if a renewal option is reasonably certain of being exercised at lease commencement, we consider several factors, including but not limited to, contract-based, asset-based and entity-based factors. We reassess the term of existing leases if there is a significant event or change in circumstances within our control that affects whether we are reasonably certain to exercise an option to extend a lease. Examples of such events or changes include construction of significant leasehold improvements or other modifications or customizations to the underlying asset, relevant business decisions or subleases. In most cases, we have concluded that renewal options are not reasonably certain of being exercised, therefore, such renewals are not included in the right of use asset and lease liability. During the nine months ended September 30, 2019, it became reasonably certain that in a future period we would exercise the first of two five years renewal options related to the office space lease for our corporate headquarters in Seattle, Washington, due to the construction of significant leasehold improvements. Therefore, the payments associated with the renewal are included in the measurement of the lease liability and right of use asset. As our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the lease commencement date in determining the present value of the lease payments. For those leases that existed as of January 1, 2019, we used our incremental borrowing rate based on information available at that date. We apply a portfolio approach for determining the incremental borrowing rate based on the applicable lease terms and the current economic environment, and we utilize the assistance of third-party specialists to assist us in determining our yield curve. The components of our operating lease expense were as follows for the periods presented (in thousands): Three Months Ended Nine Months Ended Operating lease cost $ 10,025 $ 25,552 Variable lease cost 4,631 14,377 Total lease cost $ 14,656 $ 39,929 Cash paid for amounts included in the measurement of lease liabilities for the three and nine month periods ended September 30, 2019 was $7.3 million and $23.6 million , respectively. Right of use assets obtained in exchange for new operating lease obligations for the three and nine month periods ended September 30, 2019 were $14.6 million and $128.3 million , respectively. The weighted average remaining term for our leases as of September 30, 2019 was 8.75 years . The weighted average discount rate for our leases as of September 30, 2019 was 6.5% . The following table presents the scheduled maturities of our operating lease liabilities by fiscal year as of September 30, 2019 (in thousands): Remainder of 2019 $ 7,776 2020 38,891 2021 43,073 2022 39,686 2023 39,065 All future years 179,179 Total lease payments 347,670 Less: Imputed interest (105,744 ) Present value of lease liabilities $ 241,926 Operating lease expense for the three and nine month periods ended September 30, 2018 , was $5.8 million and $17.2 million , respectively. The following table presents our future minimum payments for all operating leases as of December 31, 2018, including future minimum payments for operating leases that had not yet commenced as of December 31, 2018 totaling $112.9 million (in thousands): 2019 $ 29,085 2020 38,060 2021 40,099 2022 37,721 2023 36,458 All future years 85,462 Total future minimum lease payments $ 266,885

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt Revolving Credit Facilities To provide capital for Zillow Offers, we utilize revolving credit facilities that are classified as current liabilities in our condensed consolidated balance sheets. The following table summarizes our revolving credit facilities as of the periods presented (in thousands, except interest rates): Effective Date Maximum Borrowing Capacity Outstanding Borrowings at September 30, 2019 Outstanding Borrowings at December 31, 2018 Weighted Average Interest Rate July 31, 2018 $ 500,000 $ 432,484 $ 116,700 5.81 % January 31, 2019 500,000 265,796 — 5.77 % Total $ 1,000,000 $ 698,280 $ 116,700 Each credit facility described in the table above provides for a maximum borrowing capacity of $500.0 million . The January 31, 2019 revolving credit facility has a current borrowing capacity of $266.0 million as of September 30, 2019 , and has an initial term of two years and may be extended for up to two additional periods of six months each, subject to agreement by the lender. The July 31, 2018 revolving credit facility has an initial term of one year and automatically renews on a monthly basis as of July 31, 2019 for up to 24 additional months, subject to agreement by the lender, and has a current borrowing capacity of $442.5 million as of September 30, 2019 . Recourse under each facility is limited to the assets and equity of certain Zillow Group subsidiaries that purchase and sell select residential properties through Zillow Offers. The applicable lender is not committed to, but may in their sole discretion, advance loan funds in excess of the current borrowing capacity. Zillow Group formed certain special purpose entities to effectuate the transactions contemplated by each revolving credit facility (each, an “SPE”). Each SPE is a wholly owned subsidiary of Zillow Group and a separate legal entity, and neither the assets nor credit of any such SPE are available to satisfy the debts and other obligations of any affiliate or other entity. Outstanding amounts drawn under each credit facility are required to be repaid on the facility termination date or earlier if accelerated due to an event of default. Further, each SPE is required to repay any resulting shortfall if the value of the eligible properties owned by such SPE falls below a certain percentage of the principal amount outstanding under the applicable credit facility. Inclusion of properties in each facility is subject to various eligibility criteria. For example, a property is no longer eligible under a credit facility if such property exceeds agreed aging criteria. Each of the credit facilities permits only a portion of the financed properties to be owned longer than 180 days , and no financed properties may be owned for longer than one year . Any financed property excluded by such aging criteria will be removed from the eligible property borrowing base, and any resulting shortfall is required to be repaid. The stated interest rate on our revolving credit facilities is one-month LIBOR plus an applicable margin as defined in the respective credit agreements. Our revolving credit facilities include customary representations and warranties, covenants (including financial covenants applicable to Zillow Group) and provisions regarding events of default. As of September 30, 2019 , Zillow Group was in compliance with all financial covenants and no event of default had occurred. In certain circumstances Zillow Group may be obligated to fund some or all of the payment obligations under the credit agreements. Our revolving credit facilities also require that we establish, maintain and in certain circumstances that Zillow Group fund, certain specified reserve accounts. These reserve accounts include, but are not limited to, interest reserves, insurance, tax reserves, renovation cost reserves and reserves for specially permitted liens. Amounts funded to these reserve accounts and the collection accounts have been classified within our condensed consolidated balance sheets as restricted cash. For additional details related to our revolving credit facilities, see Note 22 herein and Note 14 in the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2018 . Warehouse Lines of Credit To provide capital for Zillow Home Loans, we utilize warehouse lines of credit that are classified as current liabilities in our condensed consolidated balance sheets. The following table summarizes our warehouse lines of credit as of the periods presented (in thousands, except interest rates): Maturity Date Maximum Borrowing Capacity Outstanding Borrowings at September 30, 2019 Outstanding Borrowings at December 31, 2018 Weighted Average Interest Rate October 15, 2019 $ 50,000 $ — $ 14,125 4.89 % June 27, 2020 50,000 30,116 18,892 4.51 % Total $ 100,000 $ 30,116 $ 33,017 On July 11, 2019, Zillow Home Loans extended the term of its $50.0 million warehouse line of credit previously maturing on July 15, 2019 such that it now matures on October 15, 2019. On June 28, 2019, Zillow Home Loans amended and restated its warehouse line of credit previously maturing on June 29, 2019. The amended and restated credit agreement extends the term of the original agreement for one year , through June 27, 2020, and continues to provide for a maximum borrowing capacity of $50.0 million with availability under the warehouse line of credit limited depending on the types of loans originated. Borrowings on the warehouse lines of credit bear interest at the one-month LIBOR plus an applicable margin, as defined in the credit agreements governing each of the warehouse lines of credit. The warehouse lines of credit include customary representations and warranties, covenants and provisions regarding events of default. As of September 30, 2019, Zillow Home Loans was in compliance with all financial covenants and no event of default had occurred. For additional details related to our warehouse lines of credit, see Note 22 . Convertible Senior Notes The following table summarizes our outstanding convertible senior notes as of the periods presented (in thousands, except interest rates): Maturity Date Aggregate Principal Amount Fair Value at September 30, 2019 Fair Value at December 31, 2018 Stated Interest Rate Effective Interest Rate September 1, 2026 $ 500,000 $ 469,375 $ — 1.375 % 8.10 % September 1, 2024 600,000 573,900 — 0.75 % 7.67 % July 1, 2023 373,750 328,818 321,855 1.50 % 6.99 % December 1, 2021 460,000 455,492 446,200 2.00 % 7.44 % December 15, 2020 9,637 16,842 16,744 2.75 % N/A Total $ 1,943,387 $ 1,844,427 $ 784,799 The convertible notes are senior unsecured obligations and are classified as long-term debt in our condensed consolidated balance sheets. Interest on the convertible notes is paid semi-annually. As of September 30, 2019 and December 31, 2018 , respectively, the total unamortized debt discount and debt issuance costs for our outstanding senior convertible notes were $464.7 million and $144.4 million . The estimated fair value of the convertible senior notes was determined through consideration of quoted market prices. The fair value is classified as Level 3 due to the limited trading activity for each of the convertible senior notes. The convertible senior notes maturing in 2021, 2023, 2024 and 2026 are not redeemable or convertible as of September 30, 2019 . The convertible senior notes maturing in 2020 are convertible, at the option of the holder, and redeemable, at our option, as of September 30, 2019 . On September 9, 2019, Zillow Group issued $600.0 million aggregate principal amount of Convertible Senior Notes due 2024 (the “2024 Notes”) and $500.0 million aggregate principal amount of Convertible Senior Notes due 2026 (the “2026 Notes”) in a private offering to qualified institutional buyers. The 2024 Notes bear interest at a fixed rate of 0.75% per year, and the 2026 Notes bear interest at a fixed rate of 1.375% per year, each payable semi-annually in arrears on March 1 and September 1 of each year, beginning on March 1, 2020. The 2024 Notes and 2026 Notes are convertible into cash, shares of Class C capital stock or a combination thereof, at our election, and may be settled as described below. The 2024 Notes and the 2026 Notes are senior, unsecured obligations of the Company, and will mature on September 1, 2024 and September 1, 2026, respectively, unless earlier repurchased, redeemed or converted in accordance with their terms. The net proceeds from the issuance of the 2024 Notes were approximately $592.2 million and the net proceeds from the issuance of the 2026 Notes were approximately $493.5 million , in each case after deducting fees and expenses payable by the Company. We used approximately $75.2 million of the net proceeds from the issuance of the 2024 Notes and approximately $75.4 million of the net proceeds from the issuance of the 2026 Notes to pay the cost of the capped call transactions entered into in connection with the issuances (“Capped Call Confirmations”) described below. The Company intends to use the remainder of the net proceeds for general corporate purposes, which may include working capital, sales and marketing activities, general and administrative matters and capital expenditures. Prior to the close of business on the business day immediately preceding March 1, 2024 (for the 2024 Notes) or March 1, 2026 (for the 2026 Notes), the 2024 Notes and the 2026 Notes will be convertible at the option of the holders only under certain conditions. On or after March 1, 2024 (for the 2024 Notes) or March 1, 2026 (for the 2026 Notes), until the close of business on the second scheduled trading day immediately preceding the applicable maturity date, holders may convert their 2024 Notes or 2026 Notes at their option at the conversion rate then in effect, irrespective of these conditions. The Company will settle conversions of the 2024 Notes and the 2026 Notes by paying or delivering, as the case may be, cash, shares of its Class C capital stock, or a combination of cash and shares of its Class C capital stock, at its election. The conversion rate for the 2024 Notes and 2026 Notes will initially be 22.9830 shares of Class C capital stock per $1,000 principal amount of 2024 Notes or 2026 Notes (equivalent to an initial conversion price of approximately $43.51 per share of Class C capital stock). The conversion rate and the corresponding conversion price will be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. The Company may redeem for cash all or part of the 2024 Notes or 2026 Notes, at its option, on or after September 5, 2022 (for the 2024 Notes) or September 5, 2023 (for the 2026 Notes), under certain circumstances, at a redemption price equal to 100% of the principal amount of the 2024 Notes or 2026 Notes, to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date (as defined in the indentures governing the 2024 Notes and 2026 Notes). The conversion option does not meet the criteria for separate accounting as a derivative as it is indexed to our own stock. If the Company undergoes a fundamental change (as defined in the indentures governing the 2024 Notes and the 2026 Notes), holders may require the Company to repurchase for cash all or part of their 2024 Notes or 2026 Notes, as applicable, at a repurchase price equal to 100% of the principal amount of the notes to be purchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date (as defined in the indentures governing the 2024 Notes and the 2026 Notes). In addition, if certain fundamental changes occur, the Company may be required, in certain circumstances, to increase the conversion rate for any 2024 Notes or 2026 Notes converted in connection with such fundamental changes by a specified number of shares of its Class C capital stock. Certain events are also considered “Events of Default,” which may result in the acceleration of the maturity of the 2024 Notes or 2026 Notes, as described in the indentures governing the 2024 Notes and 2026 Notes. There are no financial covenants associated with the 2024 Notes or 2026 Notes. The Capped Call Confirmations are expected generally to reduce the potential dilution of our Class C capital stock upon any conversion of the 2024 Notes or 2026 Notes and/or offset the cash payments the Company is required to make in excess of the principal amount of such notes in the event that the market price of the Class C capital stock is greater than the strike price of the Capped Call Confirmations (which initially corresponds to the initial conversion price of such notes and is subject to certain adjustments under the terms of the Capped Call Confirmations), with such reduction and/or offset subject to a cap based on the cap price of the Capped Call Confirmations. The Capped Call Confirmations with respect to the 2024 Notes have an initial cap price of $72.5175 per share, which represents a premium of approximately 125% over the closing price of the Company’s Class C capital stock on the Nasdaq Global Select Market on September 4, 2019, and is subject to certain adjustments under the terms of the Capped Call Confirmations. The Capped Call Confirmations with respect to the 2026 Notes have an initial cap price of $80.5750 per share, which represents a premium of approximately 150% over the closing price of the Company’s Class C capital stock on The Nasdaq Global Select Market on September 4, 2019, and is subject to certain adjustments under the terms of the Capped Call Confirmations. The Capped Call Confirmations will cover, subject to anti-dilution adjustments substantially similar to those applicable to the 2024 Notes or 2026 Notes, the number of shares of Class C capital stock that will underlie such notes. The Capped Call Confirmations do not meet the criteria for separate accounting as a derivative as they are indexed to our own stock. The premiums paid for the Capped Call Confirmations have been included as a net reduction to additional paid-in capital within shareholders’ equity. We may not redeem the 2024 Notes prior to September 5, 2022 or the 2026 Notes prior to September 5, 2023. We may redeem for cash all or any portion of the 2024 Notes or 2026 Notes, at our option, in whole or in part on or after September 5, 2022 for the 2024 Notes or on or after September 5, 2023 for the 2026 Notes if the last reported sale price per share of our Class C capital stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period. In accounting for the issuance of the 2024 Notes and the 2026 Notes, the Company separated the 2024 Notes and the 2026 Notes into liability and equity components. The carrying amount of the liability component for each of the 2024 Notes and 2026 Notes was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component, representing the conversion option, was determined by deducting the fair value of the liability component from the par value of the 2024 Notes and the 2026 Notes, respectively. The difference between the principal amounts of the 2024 Notes and the 2026 Notes and their liability components represents their respective debt discounts, which are recorded as a direct deduction from the related debt liability in the condensed consolidated balance sheet and amortized to interest expense using the effective interest method over the term of the 2024 Notes and the 2026 Notes. The equity components of the 2024 Notes and 2026 Notes of $163.6 million and $172.3 million , respectively, net of issuance costs of $2.1 million and $2.3 million , respectively, are included in additional paid-in capital in the condensed consolidated balance sheet and are not remeasured as long as they continue to meet the conditions for equity classification. For additional details related to our 2024 Notes, please see Note 22 . For additional details related to our convertible senior notes maturing in 2020, 2021, and 2023, see Note 14 in the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2018 .

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We are subject to federal and state income taxes in the United States and in Canada. As of September 30, 2019 and December 31, 2018 , we have provided a valuation allowance against our net deferred tax assets that we believe, based on the weight of available evidence, are not more likely than not to be realized. Therefore, no material current tax liability or expense has been recorded in the condensed consolidated financial statements. We have accumulated federal tax losses of approximately $1,081.7 million as of December 31, 2018 , which are available to reduce future taxable income. We have accumulated state tax losses of approximately $32.5 million (tax effected) as of December 31, 2018 . We recorded an income tax benefit of $1.3 million for the three months ended September 30, 2019 and an income tax benefit of $3.8 million for the nine months ended September 30, 2019 . We recorded an income tax benefit of $14.7 million for the three months ended September 30, 2018 , which was calculated as the difference between the income tax benefit of $22.7 million recorded for the nine months ended September 30, 2018 and the income tax benefit of $8.0 million recorded for the six months ended June 30, 2018. The $22.7 million tax benefit recorded for the nine months ended September 30, 2018 was comprised of a $1.9 million income tax benefit, which was calculated using an estimate of our annual effective tax rate of 4.3% applied to our loss before income taxes of $44.9 million for the nine months ended September 30, 2018 and a $20.8 million discrete income tax benefit as a result of the treatment of stock compensation windfall deductions and the impact from the Tax Cuts and Jobs Act (the “Tax Act”) related to IRC Section 162(m). Our estimated annual effective tax rate for the nine months ended September 30, 2018 was primarily impacted by the release in valuation allowance resulting from indefinite-lived deferred tax assets and their ability to offset indefinite-lived intangible deferred tax liabilities. As of September 30, 2018 , we had completed our accounting for the income tax effects related to the deduction limitations on compensation under the Tax Act and recorded a discrete tax benefit adjustment of $3.3 million during the three months ended September 30, 2018. The Internal Revenue Service provided further guidance in applying the written binding contracts requirement under the Tax Act and certain of our executive compensation previously eligible to be deducted for tax purposes under Section 162(m) of the Internal Revenue Code will be considered grandfathered and, therefore, will continue to be deductible. Based on the clarification of these rules, the accounting related to the Section 162(m) limitation of the Internal Revenue Code was considered complete and we recorded a $5.9 million discrete tax benefit adjustment related to this item for the nine months ended September 30, 2018 .

Share-Based Awards

Share-Based Awards	9 Months Ended
	Sep. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Awards	Share-Based Awards Option Awards The following table summarizes option award activity for the nine months ended September 30, 2019 : Number of Shares Subject to Existing Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2019 27,310,110 $ 34.04 6.23 $ 97,941 Granted 7,401,975 39.52 Exercised (1,891,111 ) 21.69 Forfeited or cancelled (1,840,756 ) 41.36 Outstanding at September 30, 2019 30,980,218 35.67 6.37 59,722 Vested and exercisable at September 30, 2019 18,305,093 32.26 4.78 55,130 The fair value of options granted is estimated at the date of grant using the Black-Scholes-Merton option-pricing model, assuming no dividends and with the following assumptions for the periods presented: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Expected volatility 45% 42% 45%-47% 42%-45% Expected dividend yield — — — — Risk-free interest rate 1.61% 2.84% 1.61%-2.53% 2.52%-2.84% Weighted-average expected life 5.00 years 4.50 years 4.75-5.25 years 4.50-5.00 years Weighted-average fair value of options granted $14.15 $19.21 $16.55 $20.89 As of September 30, 2019 , there was a total of $193.0 million in unrecognized compensation cost related to unvested stock options. 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 at January 1, 2019 5,266,324 $ 42.19 Granted 4,492,544 37.79 Vested (1,633,962 ) 40.41 Forfeited or cancelled (933,917 ) 41.38 Unvested outstanding at September 30, 2019 7,190,989 39.95 As of September 30, 2019 , there was a total of $265.6 million in unrecognized compensation cost related to unvested restricted stock units. Share-Based Compensation Expense The following table presents the effects of share-based compensation expense in our condensed consolidated statements of operations during the periods presented (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Cost of revenue $ 1,062 $ 969 $ 2,878 $ 3,180 Sales and marketing 6,588 5,911 19,039 17,413 Technology and development 18,034 15,031 51,942 40,920 General and administrative 16,444 19,771 78,025 49,853 Total $ 42,128 $ 41,682 $ 151,884 $ 111,366 On February 21, 2019, Zillow Group announced the appointment of Richard N. Barton as Zillow Group’s Chief Executive Officer, effective February 21, 2019. Mr. Barton succeeds Spencer Rascoff, who served as Zillow Group’s Chief Executive Officer since 2010 and who remains a member of Zillow Group’s board of directors. In connection with Mr. Rascoff’s resignation as Chief Executive Officer, Zillow Group entered into an Executive Departure Agreement and Release (the “Agreement”) with Mr. Rascoff. Pursuant to the Agreement, Mr. Rascoff remained a full-time employee of Zillow Group until March 22, 2019 (the “Departure Date”) in order to provide transition services until such date. Pursuant to the Agreement, Mr. Rascoff received, among other things, accelerated vesting of outstanding stock options held by Mr. Rascoff as of the Departure Date by an additional eighteen months from the Departure Date. Options not vested as of the Departure Date, taking into account the foregoing vesting acceleration, were terminated. Each of Mr. Rascoff’s vested stock options outstanding as of the Departure Date will remain exercisable until, except for any later date contemplated by the following proviso, the earlier of (x) the third anniversary of the Departure Date and (y) the latest day upon which the option would have expired by its original terms under any circumstances (the “Option Expiration Outside Date”); provided, however, that the options will remain exercisable for so long as Mr. Rascoff serves on Zillow Group’s board of directors (but not later than any applicable Option Expiration Outside Date), and if Mr. Rascoff ceases to serve on Zillow Group’s board of directors on or after the third anniversary of the Departure Date, each option will remain exercisable until the earlier of (i) ninety days from the final date of Mr. Rascoff’s service on Zillow Group’s board of directors and (ii) the applicable Option Expiration Outside Date. The change in the exercise period of the options as well as the vesting acceleration pursuant to the Agreement have been accounted for as equity modifications, and we recorded $26.4 million of share-based compensation expense associated with the modifications in the nine months ended September 30, 2019. We measured the modification charge by calculating the incremental fair value of the modified award compared to the fair value of the original award immediately prior to the modification. The value of the modified awards as of the modification date was estimated using the Black-Scholes-Merton option-pricing model, assuming no dividends, expected volatility of 46% - 47% , a risk-free interest rate of 2.47% - 2.49% and a weighted-average expected life of 3.84-5.25 years.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share For the periods presented, the following Class A common stock and Class C capital stock equivalents were excluded from the calculations of diluted net loss per share because their effect would have been antidilutive (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Weighted-average Class A common stock and Class C capital stock option awards outstanding 18,900 21,766 19,394 23,508 Weighted-average Class A common stock and Class C capital stock restricted stock units outstanding 6,964 5,072 6,690 4,891 Class A common stock issuable upon conversion of the convertible notes maturing in 2020 424 410 424 410 Total Class A common stock and Class C capital stock equivalents 26,288 27,248 26,508 28,809 Since the Company expects to settle the principal amount of the outstanding convertible notes maturing in 2021, 2023, 2024 and 2026 in cash, the Company uses the treasury stock method for calculating any potential dilutive effect of the conversion spread on diluted net income per share, if applicable. The conversion spread for each of the notes has a dilutive impact on diluted net income per share when the market price of the Company’s Class C capital stock at the end of the period exceeds the conversion price per share. The following table presents the conversion spread and conversion price per share of Class C capital stock for each of the convertible senior notes (in thousands, except per share amounts): Maturity Date Conversion Spread Conversion Price per Share September 1, 2026 11,492 $ 43.51 September 1, 2024 13,790 43.51 July 1, 2023 4,769 78.37 December 1, 2021 8,785 52.36

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Commitments We have entered into various non-cancelable operating lease agreements for certain of our office space and equipment with original lease periods expiring between 2019 and 2030 . For additional information regarding our lease agreements, see Note 12 . Purchase Commitments Purchase commitments primarily include various non-cancelable agreements to purchase content related to our mobile applications and websites as well as homes we are under contract to purchase through Zillow Offers but that have not closed as of the respective date. As of September 30, 2019 , the value of homes under contract that have not closed was $221.1 million . Letters of Credit As of September 30, 2019 , we have outstanding letters of credit of approximately $16.9 million , which secure our lease obligations in connection with certain of our office space operating leases. Surety Bonds In the course of business, we are required to provide financial commitments in the form of surety bonds to third parties as a guarantee of our performance on and our compliance with certain obligations. If we were to fail to perform or comply with these obligations, any draws upon surety bonds issued on our behalf would then trigger our payment obligation to the surety bond issuer. We have outstanding surety bonds issued for our benefit of approximately $10.1 million and $8.9 million , respectively, as of September 30, 2019 and December 31, 2018 . Legal Proceedings We are involved in a number of legal proceedings concerning matters arising in connection with the conduct of our business activities, some of which are at preliminary stages and some of which seek an indeterminate amount of damages. We regularly evaluate the status of legal proceedings in which we are involved to assess whether a loss is probable or there is a reasonable possibility that a loss or additional loss may have been incurred to determine if accruals are appropriate. We further evaluate each legal proceeding to assess whether an estimate of possible loss or range of loss can be made if accruals are not appropriate. For certain cases described below, management is unable to provide a meaningful estimate of the possible loss or range of possible loss because, among other reasons, (i) the proceedings are in preliminary stages; (ii) specific damages have not been sought; (iii) damages sought are, in our view, unsupported and/or exaggerated; (iv) there is uncertainty as to the outcome of pending appeals or motions; (v) there are significant factual issues to be resolved; and/or (vi) there are novel legal issues or unsettled legal theories presented. For these cases, however, management does not believe, based on currently available information, that the outcomes of these proceedings will have a material effect on our financial position, results of operations or cash flow. For the matters discussed below, we have not recorded any material accruals as of September 30, 2019 or December 31, 2018. In July 2015, VHT, Inc. (“VHT”) filed a complaint against us in the U.S. District Court for the Western District of Washington alleging copyright infringement of VHT’s images on the Zillow Digs site. In January 2016, VHT filed an amended complaint alleging copyright infringement of VHT’s images on the Zillow Digs site as well as the Zillow listing site. In December 2016, the court granted a motion for partial summary judgment that dismissed VHT’s claims with respect to the Zillow listing site. A federal jury trial began on January 23, 2017, and on February 9, 2017, the jury returned a verdict finding that the Company had infringed VHT’s copyrights in images displayed or saved to the Digs site. The jury awarded VHT $79,875 in actual damages and approximately $8.2 million in statutory damages. In March 2017, the Company filed motions in the district court seeking judgment for the Company on certain claims that are the subject of the verdict, and for a new trial on others. On June 20, 2017, the judge ruled and granted in part our motions, finding that VHT failed to present sufficient evidence to prove direct copyright infringement for a portion of the images, reducing the total damages to approximately $4.1 million . On March 15, 2019, after the Company had filed an appeal with the Ninth Circuit Court of Appeals seeking review of the final judgment and certain prior rulings entered by the district court, the Ninth Circuit Court of Appeals issued an opinion that, among other things, (i) affirmed the district court’s grant of summary judgment in favor of Zillow on direct infringement of images on Zillow’s listing site, (ii) affirmed the district court’s grant in favor of Zillow of judgment notwithstanding the verdict on certain images that were displayed on the Zillow Digs site, (iii) remanded consideration of the issue whether VHT’s images on the Zillow Digs site were part of a compilation or individual photos, and (iv) vacated the jury’s finding of willful infringement. On October 7, 2019, the United States Supreme Court denied VHT’s petition for writ of certiorari seeking review of certain rulings by the Ninth Circuit Court of Appeals. We do not believe there is a reasonable possibility that a material loss may be incurred related to this complaint. In August and September 2017, two purported class action lawsuits were filed against us and certain of our executive officers, alleging, among other things, violations of federal securities laws on behalf of a class of those who purchased our common stock between February 12, 2016 and August 8, 2017. One of those purported class actions, captioned Vargosko v. Zillow Group, Inc. et al, was brought in the U.S. District Court for the Central District of California. The other purported class action lawsuit, captioned Shotwell v. Zillow Group, Inc. et al, was brought in the U.S. District Court for the Western District of Washington. The complaints allege, among other things, that during the period between February 12, 2016 and August 8, 2017, we issued materially false and misleading statements regarding our business practices. The complaints seek to recover, among other things, alleged damages sustained by the purported class members as a result of the alleged misconduct. In November 2017, an amended complaint was filed against us and certain of our executive officers in the Shotwell v. Zillow Group class action lawsuit, extending the beginning of the class period to November 17, 2014. In January 2018, the Vargosko v. Zillow Group purported class action lawsuit was transferred to the U.S. District Court for the Western District of Washington and consolidated with the Shotwell v. Zillow Group purported class action lawsuit. In February 2018, the plaintiffs filed a consolidated amended complaint, and in April 2018, we filed our motion to dismiss the consolidated amended complaint. In October 2018, our motion to dismiss was granted without prejudice, and in November 2018, the plaintiffs filed a second consolidated amended complaint, which we moved to dismiss in December 2018. On April 19, 2019, our motion to dismiss the second consolidated amended complaint was denied, and we filed our answer to the second amended complaint on May 3, 2019. On October 11, 2019, plaintiffs filed a motion for class certification. We have denied the allegations of wrongdoing and intend to vigorously defend the claims in this lawsuit. We do not believe a loss related to this complaint is probable. In October and November 2017 and January and February 2018, four shareholder derivative lawsuits were filed in the U.S. District Court for the Western District of Washington and the Superior Court of the State of Washington, King County, against certain of our executive officers and directors seeking unspecified damages on behalf of the Company and certain other relief, such as reform to corporate governance practices. The plaintiffs in the derivative suits (in which the Company is a nominal defendant) allege, among other things, that the defendants breached their fiduciary duties in connection with oversight of the Company’s public statements and legal compliance, and as a result of the breach of such fiduciary duties, the Company was damaged, and defendants were unjustly enriched. Certain of the plaintiffs also allege, among other things, violations of Section 14(a) of the Securities Exchange Act of 1934 and waste of corporate assets. On February 5, 2018, the U.S. District Court for the Western District of Washington consolidated the two shareholder derivative lawsuits pending in that court. On February 16, 2018, the Superior Court of the State of Washington, King County, consolidated the two shareholder derivative lawsuits pending in that court. All four of the shareholder derivative lawsuits were stayed until our motion to dismiss the second consolidated amended complaint in the securities class action lawsuit discussed above was denied in April 2019. On July 8, 2019, the plaintiffs in the consolidated federal derivative lawsuit filed a consolidated shareholder derivative complaint, which we moved to dismiss on August 22, 2019. Plaintiffs opposed our motion to dismiss on October 7, 2019 and we filed our reply to plaintiffs’ opposition to our motion to dismiss on November 6, 2019. We do not believe a loss is probable related to these lawsuits. On September 17, 2019, International Business Machines Corporation (“IBM”) filed a complaint against us in the United States District Court for the Central District of California, alleging, among other things, that the Company has infringed and continues to willfully infringe seven patents held by IBM and seeks unspecified damages, including a request that the amount of compensatory damages be trebled, injunctive relief and costs and reasonable attorneys’ fees. We deny the allegations of any wrongdoing and intend to vigorously defend the claims in the lawsuit. There is a reasonable possibility that a loss may be incurred related to this complaint; however, the possible loss or range of loss is not estimable. In addition to the matters discussed above, from time to time, we are involved in litigation and claims that arise in the ordinary course of business. Although we cannot be certain of the outcome of any such litigation or claims, nor the amount of damages and exposure that we could incur, we currently believe that the final disposition of such matters will not have a material effect on our business, financial position, results of operations or cash flow. Regardless of the outcome, litigation can have an adverse impact on us because of defense and settlement costs, diversion of management resources and other factors. Indemnifications In the ordinary course of business, we enter into contractual arrangements under which we agree to provide indemnification of varying scope and terms to business partners and other parties with respect to certain matters, including, but not limited to, losses arising out of the breach of such agreements and out of intellectual property infringement claims made by third parties. In addition, we have agreements that indemnify certain issuers of surety bonds against losses that they may incur as a result of executing surety bonds on our behalf. For our indemnification arrangements, payment may be conditional on the other party making a claim pursuant to the procedures specified in the particular contract. Further, our obligations under these agreements may be limited in terms of time and/or amount, and in some instances, we may have recourse against third parties for certain payments. In addition, we have indemnification agreements with certain of our directors and executive officers that require us, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The terms of such obligations may vary.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions On April 3, 2019, we entered into a Charter Service Agreement with Executive Jet Management, Inc. for the occasional use by us of an aircraft owned by an entity that is owned by Mr. Lloyd Frink, our Executive Chairman and President, for business travel. We recognized approximately $0.1 million and $0.3 million in expenses pursuant to the Charter Service Agreement for the three- and nine-month periods ended September 30, 2019 , respectively.

Self-Insurance

Self-Insurance	9 Months Ended
	Sep. 30, 2019
Insurance [Abstract]
Self-Insurance	Self-Insurance We are self-insured for medical benefits and dental benefits for all qualifying Zillow Group employees. The medical plan carries a stop-loss policy which provides protection when cumulative medical claims exceed 125% of expected claims for the plan year with a limit of $1.0 million and from individual claims during the plan year exceeding $500,000 . We record estimates of the total costs of claims incurred based on an analysis of historical data and independent estimates. Our liability for self-insured claims is included within accrued compensation and benefits in our condensed consolidated balance sheets and was $3.6 million and $ 3.9 million , respectively, as of September 30, 2019 and December 31, 2018 .

Employee Benefit Plan

Employee Benefit Plan	9 Months Ended
	Sep. 30, 2019
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit Plan We have a defined contribution 401(k) retirement plan covering Zillow Group employees who have met certain eligibility requirements (the “Zillow Group 401(k) Plan”). Eligible employees may contribute pretax compensation up to a maximum amount allowable under the Internal Revenue Service limitations. Employee contributions and earnings thereon vest immediately. We currently match up to 4% of employee contributions under the Zillow Group 401(k) Plan. The total expense related to the Zillow Group 401(k) Plan was $5.6 million and $4.1 million , respectively, for the three months ended September 30, 2019 and 2018 , and $15.7 million and $11.9 million , respectively, for the nine months ended September 30, 2019 and 2018 .

Segment Information and Revenue

Segment Information and Revenue	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Information and Revenue	Segment Information and Revenue Beginning January 1, 2019, we have three operating and reportable segments, which have been identified based on the way in which our chief operating decision-maker manages our business, makes operating decisions and evaluates operating performance. The chief executive officer acts as the chief operating decision-maker and reviews financial and operational information for the Internet, Media & Technology (“IMT”), Homes and Mortgages segments. The IMT segment includes the financial results for the Premier Agent, Rentals and new construction marketplaces, dotloop, and display, as well as revenue from the sale of various other marketing and business products and services to real estate professionals. The Homes segment includes the financial results from Zillow Group’s purchase and sale of homes directly. The Mortgages segment includes financial results for advertising sold to mortgage lenders and other mortgage professionals, mortgage originations through Zillow Home Loans and the sale of mortgages on the secondary market, as well as Mortech mortgage software solutions. Revenue and costs are directly attributed to our segments when possible. However, due to the integrated structure of our business, certain costs incurred by one segment may benefit the other segments. These costs primarily include headcount-related expenses, general and administrative expenses including executive, finance, accounting, legal, human resources, recruiting, and facilities costs, product development and data acquisition costs and marketing and advertising costs. These costs are allocated to each segment based on the estimated benefit each segment receives from such expenditures. The chief executive officer reviews information about our revenue categories as well as statement of operations data inclusive of loss before income taxes by segment. This information is included in the following tables for the periods presented (in thousands): Three Months Ended Three Months Ended Homes IMT Mortgages Homes IMT Mortgages Revenue: Homes $ 384,626 $ — $ — $ 11,018 $ — $ — Premier Agent — 240,698 — — 232,703 — Rentals — 44,430 — — 37,319 — Other — 50,162 — — 43,616 — Mortgages — — 25,292 — — 18,438 Total revenue 384,626 335,290 25,292 11,018 313,638 18,438 Costs and expenses: Cost of revenue 370,796 24,318 4,721 10,226 25,186 1,260 Sales and marketing 49,186 118,514 13,647 4,650 117,522 6,562 Technology and development 20,651 94,656 8,667 6,128 93,930 5,256 General and administrative 22,174 55,749 10,570 6,010 60,678 4,055 Impairment costs — — — — 10,000 — Acquisition-related costs — — — — — 1,405 Integration costs — — 5 — — 523 Total costs and expenses 462,807 293,237 37,610 27,014 307,316 19,061 Income (loss) from operations (78,181 ) 42,053 (12,318 ) (15,996 ) 6,322 (623 ) Segment other income — — 344 — — — Segment interest expense (9,689 ) — (280 ) (432 ) — — Income (loss) before income taxes (1) $ (87,870 ) $ 42,053 $ (12,254 ) $ (16,428 ) $ 6,322 $ (623 ) Nine Months Ended Nine Months Ended Homes IMT Mortgages Homes IMT Mortgages Revenue: Homes $ 762,022 $ — $ — $ 11,018 $ — $ — Premier Agent — 690,394 — — 677,320 — Rentals — 124,938 — — 99,670 — Other — 141,899 — — 123,445 — Mortgages — — 79,637 — — 56,766 Total revenue 762,022 957,231 79,637 11,018 900,435 56,766 Costs and expenses: Cost of revenue 733,947 74,628 13,829 10,312 72,070 3,736 Sales and marketing 107,457 380,608 42,302 7,035 384,241 22,476 Technology and development 51,130 276,886 24,058 12,154 270,978 16,491 General and administrative 54,339 181,270 31,497 11,964 163,303 12,128 Impairment costs — — — — 10,000 — Acquisition-related costs — — — — 27 2,037 Integration costs — — 650 — — 523 Total costs and expenses 946,873 913,392 112,336 41,465 900,619 57,391 Income (loss) from operations (184,851 ) 43,839 (32,699 ) (30,447 ) (184 ) (625 ) Segment other income — — 1,059 — — — Segment interest expense (19,346 ) — (668 ) (432 ) — — Income (loss) before income taxes (1) $ (204,197 ) $ 43,839 $ (32,308 ) $ (30,879 ) $ (184 ) $ (625 ) (1) The following table presents the reconciliation of total segment loss before income taxes to consolidated loss before income taxes for the periods presented (in thousands, unaudited): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Total segment loss before income taxes $ (58,071 ) $ (10,729 ) $ (192,666 ) $ (31,688 ) Corporate interest expense (16,533 ) (12,236 ) (41,851 ) (26,496 ) Corporate other income 8,655 7,773 26,566 13,308 Consolidated loss before income taxes $ (65,949 ) $ (15,192 ) $ (207,951 ) $ (44,876 ) Certain corporate items are not directly attributable to any of our segments, including interest income earned on our short-term investments included in Other income and interest costs on our convertible senior notes included in Interest expense.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Issuance of Additional 0.75% Convertible Senior Notes due in 2024 On October 9, 2019, the Company issued $73.0 million aggregate principal amount of 0.75% Convertible Senior Notes due 2024 (the “Additional Notes”). The Additional Notes were sold pursuant to the initial purchasers’ partial exercise of their option to purchase such notes, granted in connection with the offering of the 2024 Notes. For additional details related to the 2024 Notes, please see Note 13. The Additional Notes have the same terms, and were issued under the same indenture, as the 2024 Notes. The net proceeds from the offering of the Additional Notes were approximately $72.0 million , after deducting fees and expenses payable by the Company. The Company used approximately $9.1 million of the net proceeds to pay the cost of the capped call transactions entered into in connection with the issuance of the Additional Notes. The Additional Notes will be separated into liability and equity components, with the liability component classified as long-term debt and the equity component, reflecting the conversion option, included in additional paid-in capital in our consolidated balance sheet. The premiums paid for the capped call confirmations will be included as a net reduction to additional paid-in capital within shareholders’ equity. Extension of Warehouse Line of Credit On October 11, 2019, Zillow Home Loans extended the term of its $50.0 million warehouse line of credit previously maturing on October 15, 2019 such that it now matures on October 31, 2019. Entry into Revolving Credit Agreement On October 21, 2019, certain of Zillow Group’s wholly owned subsidiaries entered into a credit agreement with Goldman Sachs Bank USA, as the lender, and certain other parties thereto (the “GS Credit Agreement”). The GS Credit Agreement provides for a maximum borrowing capacity of $500.0 million (the “Maximum Amount”) subject to the satisfaction of certain conditions, through a credit facility secured by a pledge of the assets and equity of certain subsidiaries that purchase and sell select residential properties through Zillow Offers. The lender has the discretion to determine the borrowing capacity available under the credit facility, up to the Maximum Amount. The GS Credit Agreement has an initial term of two years which may be extended for one additional period of six months , subject to the satisfaction of certain conditions. The stated interest rate is one-month LIBOR plus an applicable margin. The GS Credit Agreement includes customary representations and warranties, covenants (including financial covenants applicable to Zillow Group), and provisions regarding events of default. The GS Credit Agreement includes repayment terms similar to the repayment terms under our other two credit facilities that finance the purchase of residential properties through Zillow Offers. The GS Credit Agreement will be classified within current liabilities in our consolidated balance sheet. Recourse under the credit facility is limited to the assets and equity of certain Zillow Group subsidiaries that purchase and sell select residential properties through Zillow Offers. Zillow Group formed certain special purpose entities to effectuate the transactions contemplated by the GS Credit Agreement (each, an “SPE”). Each SPE is a wholly owned subsidiary of Zillow Group and a separate legal entity, and neither the assets nor credit of any such SPE are available to satisfy the debts and other obligations of any affiliate or other entity. In certain circumstances Zillow Group may be obligated to fund some or all of the payment obligations under the credit facility. Entry into Master Repurchase Agreement On October 29, 2019, Zillow Home Loans, LLC (“Zillow Homes Loans”) entered into a master repurchase agreement (the “Repurchase Agreement”) with Citibank, N.A. (“Citibank”) to provide funding for mortgage loans. In accordance with the Repurchase Agreement, Citibank agrees to pay Zillow Home Loans a negotiated purchase price for eligible loans and Zillow Home Loans simultaneously agrees to repurchase such loans from Citibank under a specified timeframe at an agreed upon price that includes interest. The Repurchase Agreement provides for a maximum borrowing capacity of $75.0 million , including a committed amount of $25.0 million

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements include Zillow Group, Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and accompanying notes included in Zillow Group, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2018 , which was filed with the SEC on February 21, 2019. The condensed consolidated balance sheet as of December 31, 2018 , included herein, was derived from the audited financial statements of Zillow Group, Inc. as of that date. The unaudited condensed consolidated interim financial statements, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly our financial position as of September 30, 2019 , our results of operations, comprehensive loss and shareholders’ equity for the three and nine month periods ended September 30, 2019 and 2018 , and our cash flows for the nine month periods ended September 30, 2019 and 2018 . The results of the three and nine month periods 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.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenue and expenses during the periods presented. On an ongoing basis, we evaluate our estimates, including those related to the net realizable value of inventory, amortization period and recoverability of contract cost assets, website and software development costs, recoverability of long-lived assets and intangible assets with definite lives, share-based compensation, income taxes, business combinations and the recoverability of goodwill and indefinite-lived intangible assets, among others. To the extent there are material differences between these estimates, judgments or assumptions and actual results, our financial statements will be affected.
Recently Issued Accounting Standards Not Yet Adopted	Recently Issued Accounting Standards Not Yet Adopted In August 2018, the Financial Accounting Standards Board (“FASB”) issued guidance related to a customer’s accounting for implementation costs incurred in hosting arrangements. The guidance conforms the requirements for capitalizing implementation costs incurred in cloud computing arrangements that are service contracts with the accounting guidance that provides for the capitalization of costs incurred to develop or obtain internal-use software. Under the guidance, implementation costs that are capitalized should be characterized in financial statements in the same manner as other service costs and assets related to service costs and amortized over the term of the hosting arrangement. This guidance is effective for interim and annual reporting periods beginning after December 15, 2019, and early adoption is permitted. Entities are permitted to apply either a retrospective or prospective transition approach to adopt this guidance. We expect to adopt this guidance on January 1, 2020 using the prospective transition approach, under which we will apply the guidance to all eligible costs incurred subsequent to adoption. We have not historically incurred material amounts of implementation costs for cloud computing arrangements, however, we are continuing to assess the impact the adoption of this guidance will have on our financial position, results of operations and cash flows. In August 2018, the FASB issued guidance related to disclosure requirements for fair value measurements. This guidance removes, modifies and adds disclosures related to certain assets and liabilities measured at fair value. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim and annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. This guidance is effective for interim and annual periods beginning after December 15, 2019, and early adoption is permitted. We expect to adopt this guidance on January 1, 2020. We have not historically recorded material amounts of Level 3 assets and liabilities or material transfers of assets or liabilities between levels within the fair value hierarchy. However, we are continuing to assess the impact the adoption of this guidance will have on our financial statement disclosures. In June 2016, and subsequently amended in April 2019 and May 2019, the FASB issued guidance on the measurement of credit losses on financial assets. This guidance will require an entity to measure and recognize expected credit losses for certain financial instruments and financial assets, including trade receivables. This guidance requires an entity to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument on initial recognition and at each reporting period, whereas current guidance employs an incurred loss methodology. This guidance is effective for interim and annual periods beginning after December 15, 2019, and early adoption is permitted for interim and annual reporting periods beginning after December 15, 2018. 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 adopted. We expect to adopt this guidance on January 1, 2020. We are currently evaluating necessary changes to our accounting policies, processes and systems as a result of the adoption of the guidance, primarily related to our trade accounts receivable and certain available-for-sale investments. We continue to assess the impact the adoption of this guidance will have on our financial position, results of operations and cash flows.
Fair Value Measurements	Accounting standards define fair value as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The standards also establish a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Assets and liabilities valued based on observable market data for similar instruments, such as quoted prices for similar assets or liabilities. • Level 3—Unobservable inputs that are supported by little or no market activity; instruments valued based on the best available data, some of which is internally developed, and considers risk premiums that a market participant would require. We applied the following methods and assumptions in estimating our fair value measurements: Cash equivalents — The fair value measurement of money market funds is based on quoted market prices in active markets. The fair value measurement of certificates of deposit and commercial paper is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means. Short-term investments — The fair value measurement of our short-term investments is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means. Restricted cash — Restricted cash consists of cash received from the resale of homes through Zillow Offers which may be used to repay amounts borrowed on our revolving credit facilities (see Note 13 ) and amounts held in escrow related to funding home purchases in our mortgage origination business. The carrying value of restricted cash approximates fair value due to the short period of time amounts borrowed on the revolving credit facilities are outstanding. Mortgage loans held for sale — The fair value of mortgage loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Interest rate lock commitments — The fair value of interest rate lock commitments (“IRLCs”) is calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Expired commitments are excluded from the fair value measurement. We generally only issue IRLCs for products that meet specific purchaser guidelines. Since not all IRLCs will become closed loans, we adjust our fair value measurements for the estimated amount of IRLCs that will not close. Forward contracts — The fair value of mandatory loan sales commitments and derivative instruments such as forward sales of mortgage-backed securities that are utilized as hedging instruments are calculated by reference to quoted prices for similar assets.
Segment Reporting	Beginning January 1, 2019, we have three operating and reportable segments, which have been identified based on the way in which our chief operating decision-maker manages our business, makes operating decisions and evaluates operating performance. The chief executive officer acts as the chief operating decision-maker and reviews financial and operational information for the Internet, Media & Technology (“IMT”), Homes and Mortgages segments. The IMT segment includes the financial results for the Premier Agent, Rentals and new construction marketplaces, dotloop, and display, as well as revenue from the sale of various other marketing and business products and services to real estate professionals. The Homes segment includes the financial results from Zillow Group’s purchase and sale of homes directly. The Mortgages segment includes financial results for advertising sold to mortgage lenders and other mortgage professionals, mortgage originations through Zillow Home Loans and the sale of mortgages on the secondary market, as well as Mortech mortgage software solutions. Revenue and costs are directly attributed to our segments when possible. However, due to the integrated structure of our business, certain costs incurred by one segment may benefit the other segments. These costs primarily include headcount-related expenses, general and administrative expenses including executive, finance, accounting, legal, human resources, recruiting, and facilities costs, product development and data acquisition costs and marketing and advertising costs. These costs are allocated to each segment based on the estimated benefit each segment receives from such expenditures.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Summary of Balances of Cash Equivalents and Investments	The following tables present the balances of assets and liabilities measured at fair value on a recurring basis, by level within the fair value hierarchy, as of the dates presented (in thousands): September 30, 2019 Total Level 1 Level 2 Cash equivalents: Money market funds $ 1,353,600 $ 1,353,600 $ — Certificates of deposit 742 — 742 Short-term investments: U.S. government agency securities 350,665 — 350,665 Commercial paper 68,915 — 68,915 Corporate notes and bonds 63,585 — 63,585 Treasury bills 29,911 — 29,911 Municipal securities 18,603 — 18,603 Mortgage origination-related: Mortgage loans held for sale 36,762 — 36,762 IRLCs 1,503 — 1,503 Forward contracts - other current assets 84 — 84 Forward contracts - other current liabilities (184 ) — (184 ) Total $ 1,924,186 $ 1,353,600 $ 570,586 December 31, 2018 Total Level 1 Level 2 Cash equivalents: Money market funds $ 541,575 $ 541,575 $ — Commercial paper 3,999 — 3,999 Short-term investments: U.S. government agency securities 646,496 — 646,496 Corporate notes and bonds 112,933 — 112,933 Commercial paper 85,506 — 85,506 Municipal securities 39,306 — 39,306 Foreign government securities 14,915 — 14,915 Certificates of deposit 4,711 — 4,711 Mortgage origination-related: Mortgage loans held for sale 35,409 — 35,409 IRLCs 847 — 847 Forward contracts - other current liabilities (125 ) — (125 ) Total $ 1,485,572 $ 541,575 $ 943,997

Cash and Cash Equivalents, Sh_2

Cash and Cash Equivalents, Short-term Investments and Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2019
Cash and Cash Equivalents [Abstract]
Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Market Value of Cash and Cash Equivalents and Available-for-Sale Investments	The following tables present the amortized cost, gross unrealized gains and losses and estimated fair market value of our cash and cash equivalents, available-for-sale investments and restricted cash as of the dates presented (in thousands): September 30, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 437,576 $ — $ — $ 437,576 Cash equivalents: Money market funds 1,353,600 — — 1,353,600 Certificates of deposit 742 — — 742 Short-term investments: U.S. government agency securities 350,153 514 (2 ) 350,665 Commercial paper 68,915 — — 68,915 Corporate notes and bonds 63,419 166 — 63,585 Treasury bills 29,900 11 — 29,911 Municipal securities 18,511 92 — 18,603 Restricted cash 75,004 — — 75,004 Total $ 2,397,820 $ 783 $ (2 ) $ 2,398,601 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 105,484 $ — $ — $ 105,484 Cash equivalents: Money market funds 541,575 — — 541,575 Commercial paper 3,999 — — 3,999 Short-term investments: U.S. government agency securities 647,266 51 (821 ) 646,496 Corporate notes and bonds 113,109 1 (177 ) 112,933 Commercial paper 85,506 — — 85,506 Municipal securities 39,316 23 (33 ) 39,306 Foreign government securities 14,929 — (14 ) 14,915 Certificates of deposit 4,711 1 (1 ) 4,711 Restricted cash 12,385 — — 12,385 Total $ 1,568,280 $ 76 $ (1,046 ) $ 1,567,310

Accounts Receivable, net (Table

Accounts Receivable, net (Tables)	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Schedule of Accounts Receivable, Net	The following table presents the changes in the allowance for doubtful accounts (in thousands): Balance as of January 1, 2019 $ 4,838 Bad debt expense 1,894 Less: write-offs, net of recoveries and other adjustments (2,268 ) Balance as of September 30, 2019 $ 4,464

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Components of Net Inventory	The following table presents the components of inventory, net of applicable lower of cost or net realizable value adjustments, as of the dates presented (in thousands): September 30, December 31, Work-in-process $ 196,295 $ 45,943 Finished goods 683,058 116,886 Inventory $ 879,353 $ 162,829

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	9 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Detail of Property and Equipment	The following table presents the detail of property and equipment as of the dates presented (in thousands): September 30, December 31, Website development costs $ 151,314 $ 149,891 Leasehold improvements 79,216 65,012 Office equipment, furniture and fixtures 34,801 39,510 Computer equipment 33,349 22,477 Construction-in-progress 26,519 29,037 Property and equipment 325,199 305,927 Less: accumulated amortization and depreciation (170,948 ) (170,755 ) Property and equipment, net $ 154,251 $ 135,172

Intangible Assets, net (Tables)

Intangible Assets, net (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	The following tables present the detail of intangible assets subject to amortization as of the dates presented (in thousands): September 30, 2019 Cost Accumulated Amortization Net Purchased content $ 45,542 $ (38,095 ) $ 7,447 Software 32,959 (18,577 ) 14,382 Customer relationships 103,300 (70,354 ) 32,946 Developed technology 107,200 (78,284 ) 28,916 Lender licenses 400 (167 ) 233 Intangibles-in-progress 5,603 — 5,603 Total $ 295,004 $ (205,477 ) $ 89,527 December 31, 2018 Cost Accumulated Amortization Net Purchased content $ 42,110 $ (30,477 ) $ 11,633 Software 24,296 (13,925 ) 10,371 Customer relationships 103,900 (60,733 ) 43,167 Developed technology 111,980 (72,788 ) 39,192 Trade names and trademarks 4,900 (4,683 ) 217 Lender licenses 400 (17 ) 383 Intangibles-in-progress 2,941 — 2,941 Total $ 290,527 $ (182,623 ) $ 107,904

Deferred Revenue (Tables)

Deferred Revenue (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Schedule of Change in Deferred Revenue	The following tables present the changes in deferred revenue for the periods presented (in thousands): Three Months Ended Balance as of July 1, 2019 $ 37,080 Deferral of revenue 300,715 Less: Revenue recognized (295,840 ) Balance as of September 30, 2019 $ 41,955 Nine Months Ended Balance as of January 1, 2019 $ 34,080 Deferral of revenue 802,699 Less: Revenue recognized (794,824 ) Balance as of September 30, 2019 $ 41,955

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Components of Lease Expense	The components of our operating lease expense were as follows for the periods presented (in thousands): Three Months Ended Nine Months Ended Operating lease cost $ 10,025 $ 25,552 Variable lease cost 4,631 14,377 Total lease cost $ 14,656 $ 39,929
Schedule of Maturities for Operating Lease Liabilities	The following table presents the scheduled maturities of our operating lease liabilities by fiscal year as of September 30, 2019 (in thousands): Remainder of 2019 $ 7,776 2020 38,891 2021 43,073 2022 39,686 2023 39,065 All future years 179,179 Total lease payments 347,670 Less: Imputed interest (105,744 ) Present value of lease liabilities $ 241,926
Schedule of Future Minimum Payments for Operating Leases	The following table presents our future minimum payments for all operating leases as of December 31, 2018, including future minimum payments for operating leases that had not yet commenced as of December 31, 2018 totaling $112.9 million (in thousands): 2019 $ 29,085 2020 38,060 2021 40,099 2022 37,721 2023 36,458 All future years 85,462 Total future minimum lease payments $ 266,885

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of Revolving Credit Facilities and Lines of Credit	The following table summarizes our warehouse lines of credit as of the periods presented (in thousands, except interest rates): Maturity Date Maximum Borrowing Capacity Outstanding Borrowings at September 30, 2019 Outstanding Borrowings at December 31, 2018 Weighted Average Interest Rate October 15, 2019 $ 50,000 $ — $ 14,125 4.89 % June 27, 2020 50,000 30,116 18,892 4.51 % Total $ 100,000 $ 30,116 $ 33,017 Effective Date Maximum Borrowing Capacity Outstanding Borrowings at September 30, 2019 Outstanding Borrowings at December 31, 2018 Weighted Average Interest Rate July 31, 2018 $ 500,000 $ 432,484 $ 116,700 5.81 % January 31, 2019 500,000 265,796 — 5.77 % Total $ 1,000,000 $ 698,280 $ 116,700
Schedule of Convertible Senior Notes	The following table summarizes our outstanding convertible senior notes as of the periods presented (in thousands, except interest rates): Maturity Date Aggregate Principal Amount Fair Value at September 30, 2019 Fair Value at December 31, 2018 Stated Interest Rate Effective Interest Rate September 1, 2026 $ 500,000 $ 469,375 $ — 1.375 % 8.10 % September 1, 2024 600,000 573,900 — 0.75 % 7.67 % July 1, 2023 373,750 328,818 321,855 1.50 % 6.99 % December 1, 2021 460,000 455,492 446,200 2.00 % 7.44 % December 15, 2020 9,637 16,842 16,744 2.75 % N/A Total $ 1,943,387 $ 1,844,427 $ 784,799

Share-Based Awards (Tables)

Share-Based Awards (Tables)	9 Months Ended
	Sep. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Option Award Activity	The following table summarizes option award activity for the nine months ended September 30, 2019 : Number of Shares Subject to Existing Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2019 27,310,110 $ 34.04 6.23 $ 97,941 Granted 7,401,975 39.52 Exercised (1,891,111 ) 21.69 Forfeited or cancelled (1,840,756 ) 41.36 Outstanding at September 30, 2019 30,980,218 35.67 6.37 59,722 Vested and exercisable at September 30, 2019 18,305,093 32.26 4.78 55,130
Fair Value of Options Granted, Estimated at Date of Grant Using Black Scholes Merton Option Pricing Model	The fair value of options granted is estimated at the date of grant using the Black-Scholes-Merton option-pricing model, assuming no dividends and with the following assumptions for the periods presented: Three Months Ended Nine Months Ended 2019 2018 2019 2018 Expected volatility 45% 42% 45%-47% 42%-45% Expected dividend yield — — — — Risk-free interest rate 1.61% 2.84% 1.61%-2.53% 2.52%-2.84% Weighted-average expected life 5.00 years 4.50 years 4.75-5.25 years 4.50-5.00 years Weighted-average fair value of options granted $14.15 $19.21 $16.55 $20.89
Summary of 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 at January 1, 2019 5,266,324 $ 42.19 Granted 4,492,544 37.79 Vested (1,633,962 ) 40.41 Forfeited or cancelled (933,917 ) 41.38 Unvested outstanding at September 30, 2019 7,190,989 39.95
Effects of Share Based Compensation in Consolidated Statements of Operations	The following table presents the effects of share-based compensation expense in our condensed consolidated statements of operations during the periods presented (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Cost of revenue $ 1,062 $ 969 $ 2,878 $ 3,180 Sales and marketing 6,588 5,911 19,039 17,413 Technology and development 18,034 15,031 51,942 40,920 General and administrative 16,444 19,771 78,025 49,853 Total $ 42,128 $ 41,682 $ 151,884 $ 111,366

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share	For the periods presented, the following Class A common stock and Class C capital stock equivalents were excluded from the calculations of diluted net loss per share because their effect would have been antidilutive (in thousands): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Weighted-average Class A common stock and Class C capital stock option awards outstanding 18,900 21,766 19,394 23,508 Weighted-average Class A common stock and Class C capital stock restricted stock units outstanding 6,964 5,072 6,690 4,891 Class A common stock issuable upon conversion of the convertible notes maturing in 2020 424 410 424 410 Total Class A common stock and Class C capital stock equivalents 26,288 27,248 26,508 28,809 Maturity Date Conversion Spread Conversion Price per Share September 1, 2026 11,492 $ 43.51 September 1, 2024 13,790 43.51 July 1, 2023 4,769 78.37 December 1, 2021 8,785 52.36

Segment Information and Reven_2

Segment Information and Revenue (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Revenue Categories	This information is included in the following tables for the periods presented (in thousands): Three Months Ended Three Months Ended Homes IMT Mortgages Homes IMT Mortgages Revenue: Homes $ 384,626 $ — $ — $ 11,018 $ — $ — Premier Agent — 240,698 — — 232,703 — Rentals — 44,430 — — 37,319 — Other — 50,162 — — 43,616 — Mortgages — — 25,292 — — 18,438 Total revenue 384,626 335,290 25,292 11,018 313,638 18,438 Costs and expenses: Cost of revenue 370,796 24,318 4,721 10,226 25,186 1,260 Sales and marketing 49,186 118,514 13,647 4,650 117,522 6,562 Technology and development 20,651 94,656 8,667 6,128 93,930 5,256 General and administrative 22,174 55,749 10,570 6,010 60,678 4,055 Impairment costs — — — — 10,000 — Acquisition-related costs — — — — — 1,405 Integration costs — — 5 — — 523 Total costs and expenses 462,807 293,237 37,610 27,014 307,316 19,061 Income (loss) from operations (78,181 ) 42,053 (12,318 ) (15,996 ) 6,322 (623 ) Segment other income — — 344 — — — Segment interest expense (9,689 ) — (280 ) (432 ) — — Income (loss) before income taxes (1) $ (87,870 ) $ 42,053 $ (12,254 ) $ (16,428 ) $ 6,322 $ (623 ) Nine Months Ended Nine Months Ended Homes IMT Mortgages Homes IMT Mortgages Revenue: Homes $ 762,022 $ — $ — $ 11,018 $ — $ — Premier Agent — 690,394 — — 677,320 — Rentals — 124,938 — — 99,670 — Other — 141,899 — — 123,445 — Mortgages — — 79,637 — — 56,766 Total revenue 762,022 957,231 79,637 11,018 900,435 56,766 Costs and expenses: Cost of revenue 733,947 74,628 13,829 10,312 72,070 3,736 Sales and marketing 107,457 380,608 42,302 7,035 384,241 22,476 Technology and development 51,130 276,886 24,058 12,154 270,978 16,491 General and administrative 54,339 181,270 31,497 11,964 163,303 12,128 Impairment costs — — — — 10,000 — Acquisition-related costs — — — — 27 2,037 Integration costs — — 650 — — 523 Total costs and expenses 946,873 913,392 112,336 41,465 900,619 57,391 Income (loss) from operations (184,851 ) 43,839 (32,699 ) (30,447 ) (184 ) (625 ) Segment other income — — 1,059 — — — Segment interest expense (19,346 ) — (668 ) (432 ) — — Income (loss) before income taxes (1) $ (204,197 ) $ 43,839 $ (32,308 ) $ (30,879 ) $ (184 ) $ (625 ) (1) The following table presents the reconciliation of total segment loss before income taxes to consolidated loss before income taxes for the periods presented (in thousands, unaudited): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Total segment loss before income taxes $ (58,071 ) $ (10,729 ) $ (192,666 ) $ (31,688 ) Corporate interest expense (16,533 ) (12,236 ) (41,851 ) (26,496 ) Corporate other income 8,655 7,773 26,566 13,308 Consolidated loss before income taxes $ (65,949 ) $ (15,192 ) $ (207,951 ) $ (44,876 )
Reconciliation of Segment Gross Profit and Loss	The following table presents the reconciliation of total segment loss before income taxes to consolidated loss before income taxes for the periods presented (in thousands, unaudited): Three Months Ended Nine Months Ended 2019 2018 2019 2018 Total segment loss before income taxes $ (58,071 ) $ (10,729 ) $ (192,666 ) $ (31,688 ) Corporate interest expense (16,533 ) (12,236 ) (41,851 ) (26,496 ) Corporate other income 8,655 7,773 26,566 13,308 Consolidated loss before income taxes $ (65,949 ) $ (15,192 ) $ (207,951 ) $ (44,876 )

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Cash Equivalents and Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	$ 36,762	$ 35,409
Total	1,924,186	1,485,572
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	0	0
Total	1,353,600	541,575
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	36,762	35,409
Total	570,586	943,997
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,353,600	541,575
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,353,600	541,575
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	742
Short-term investments		4,711
Certificates of deposit | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0
Short-term investments		0
Certificates of deposit | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	742
Short-term investments		4,711
U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	350,665	646,496
U.S. government agency securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
U.S. government agency securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	350,665	646,496
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		3,999
Short-term investments	68,915	85,506
Commercial paper | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Commercial paper | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		3,999
Short-term investments	68,915	85,506
Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	63,585	112,933
Corporate notes and bonds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Corporate notes and bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	63,585	112,933
Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	18,603	39,306
Municipal securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Municipal securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	18,603	39,306
Foreign government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		14,915
Foreign government securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		0
Foreign government securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		14,915
Treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	29,911
Treasury bills | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0
Treasury bills | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	29,911
IRLCs | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,503	847
IRLCs | Level 1 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
IRLCs | Level 2 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,503	847
Forward contracts | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	84	(125)
Derivative liability	(184)
Forward contracts | Level 1 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liability	0
Forward contracts | Level 2 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	84	$ (125)
Derivative liability	$ (184)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value	$ 0	$ 0
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Mortgage Loans Held For Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	57.9	26.7
IRLCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	$ 99.8	$ 28.8

Cash and Cash Equivalents, Sh_3

Cash and Cash Equivalents, Short-term Investments and Restricted Cash - Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Market Value of Cash and Cash Equivalents and Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 1,791,918	$ 651,058
Short-term investments:
Gross Unrealized Gains	783	76
Gross Unrealized Losses	(2)	(1,046)
Restricted cash	75,004	12,385
Cash, cash equivalents, short-term investments, and restricted cash, amortized cost	2,397,820	1,568,280
Cash, cash equivalents, short-term investments, and restricted cash, estimated fair market value	2,398,601	1,567,310
U.S. government agency securities
Short-term investments:
Amortized Cost	350,153	647,266
Gross Unrealized Gains	514	51
Gross Unrealized Losses	(2)	(821)
Estimated Fair Market Value	350,665	646,496
Corporate notes and bonds
Short-term investments:
Amortized Cost	63,419	113,109
Gross Unrealized Gains	166	1
Gross Unrealized Losses	0	(177)
Estimated Fair Market Value	63,585	112,933
Commercial paper
Short-term investments:
Amortized Cost	68,915	85,506
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	68,915	85,506
Municipal securities
Short-term investments:
Amortized Cost	18,511	39,316
Gross Unrealized Gains	92	23
Gross Unrealized Losses	0	(33)
Estimated Fair Market Value	18,603	39,306
Foreign government securities
Short-term investments:
Amortized Cost		14,929
Gross Unrealized Gains		0
Gross Unrealized Losses		(14)
Estimated Fair Market Value		14,915
Certificates of deposit
Short-term investments:
Amortized Cost		4,711
Gross Unrealized Gains		1
Gross Unrealized Losses		(1)
Estimated Fair Market Value		4,711
Treasury bills
Short-term investments:
Amortized Cost	29,900
Gross Unrealized Gains	11
Gross Unrealized Losses	0
Estimated Fair Market Value	29,911
Cash
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	437,576	105,484
Money market funds
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	1,353,600	541,575
Certificates of deposit
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 742
Commercial paper
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents		$ 3,999

Accounts Receivable, net (Detai

Accounts Receivable, net (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Receivables [Abstract]
Accounts receivable, net	$ 77,674		$ 66,083
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	4,838
Bad debt expense	1,894	$ 1,053
Less: write-offs, net of recoveries and other adjustments	(2,268)
Ending balance	$ 4,464

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Work-in-process	$ 196,295	$ 45,943
Finished goods	683,058	116,886
Inventory	$ 879,353	$ 162,829

Contract Cost Assets (Details)

Contract Cost Assets (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract cost assets	$ 46,047,000		$ 46,047,000		$ 45,819,000
Impairment of contract cost assets	0	$ 0	0	$ 0
Amortization of contract cost assets	$ 8,800,000	$ 8,900,000	$ 26,722,000	$ 27,227,000

Property and Equipment, net - D

Property and Equipment, net - Detail of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment	$ 325,199	$ 305,927
Less: accumulated amortization and depreciation	(170,948)	(170,755)
Property and equipment, net	154,251	135,172
Website development costs
Property, Plant and Equipment [Line Items]
Property and equipment	151,314	149,891
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	79,216	65,012
Office equipment, furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	34,801	39,510
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	33,349	22,477
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property and equipment	$ 26,519	$ 29,037

Property and Equipment, net - A

Property and Equipment, net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Amortization and depreciation expense related to property and equipment other than website development costs	$ 6.1	$ 5.1	$ 18.5	$ 14.2
Capitalization of website development costs	10.8	8	31.1	26.6
Amortization of website development costs and intangible assets included in technology and development	11.1	12	33.1	37.6
Technology and development | Software Development
Property, Plant and Equipment [Line Items]
Amortization of website development costs and intangible assets included in technology and development	$ 4.8	$ 6.2	$ 11.8	$ 24.2

Equity Investment - Additional

Equity Investment - Additional Information (Detail) - October 2016 Investment - USD ($)	1 Months Ended
	Oct. 31, 2016	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Cumulative impairment charge		$ 0
Upward adjustments		0
Downward adjustments		0
Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Percentage of equity interest held	10.00%
Equity investments	$ 10,000,000
Maximum exposure to loss		$ 10,000,000

Intangible Assets, net - Intang

Intangible Assets, net - Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Cost	$ 295,004	$ 290,527
Accumulated Amortization	(205,477)	(182,623)
Net	89,527	107,904
Purchased content
Finite-Lived Intangible Assets [Line Items]
Cost	45,542	42,110
Accumulated Amortization	(38,095)	(30,477)
Net	7,447	11,633
Software
Finite-Lived Intangible Assets [Line Items]
Cost	32,959	24,296
Accumulated Amortization	(18,577)	(13,925)
Net	14,382	10,371
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	103,300	103,900
Accumulated Amortization	(70,354)	(60,733)
Net	32,946	43,167
Developed technology
Finite-Lived Intangible Assets [Line Items]
Cost	107,200	111,980
Accumulated Amortization	(78,284)	(72,788)
Net	28,916	39,192
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Cost		4,900
Accumulated Amortization		(4,683)
Net		217
Lender licenses
Finite-Lived Intangible Assets [Line Items]
Cost	400	400
Accumulated Amortization	(167)	(17)
Net	233	383
Intangibles-in-progress
Finite-Lived Intangible Assets [Line Items]
Cost	5,603	2,941
Accumulated Amortization	0	0
Net	$ 5,603	$ 2,941

Intangible Assets, net - Additi

Intangible Assets, net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Indefinite-lived Intangible Assets [Line Items]
Amortization of website development costs and intangible assets included in technology and development	$ 11.1	$ 12	$ 33.1	$ 37.6
Trade names and trademarks | Trulia
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible asset	$ 108		$ 108		$ 108

Deferred Revenue (Details)

Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Change in Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 37,080	$ 34,080
Deferral of revenue	300,715	802,699
Less: Revenue recognized	(295,840)	(794,824)
Ending balance	41,955	41,955
Revenue recognized, recorded in deferred revenue as of prior period	$ 34,200	$ 31,500

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)renewal_option	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Lessee, Lease, Description [Line Items]
Option to extend lease	10 years		10 years
Number of periods | renewal_option			2
Option to extend existing lease			5 years
Cash paid for amounts included in measurement of lease liabilities	$ 7.3		$ 23.6
Right of use assets obtained in exchange for new operating lease obligations	$ 14.6		$ 128.3
Weighted average remaining lease term	8 years 9 months		8 years 9 months
Weighted average discount rate	6.50%		6.50%
Operating lease expense		$ 5.8		$ 17.2
Operating leases not yet commenced					$ 112.9
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term			1 year
Number of periods | renewal_option			1
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term			12 years
Number of periods | renewal_option			2

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 10,025	$ 25,552
Variable lease cost	4,631	14,377
Total lease cost	$ 14,656	$ 39,929

Leases - Schedule of Maturities

Leases - Schedule of Maturities for Operating Lease Liabilities (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
Remainder of 2019	$ 7,776
2020	38,891
2021	43,073
2022	39,686
2023	39,065
All future years	179,179
Total lease payments	347,670
Less: Imputed interest	(105,744)
Present value of lease liabilities	$ 241,926

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 29,085
2020	38,060
2021	40,099
2022	37,721
2023	36,458
All future years	85,462
Total future minimum lease payments	$ 266,885

Debt - Schedule of Revolving Cr

Debt - Schedule of Revolving Credit Facilities (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Outstanding borrowings on revolving credit facility	$ 698,280,000	$ 116,700,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum Borrowing Capacity	1,000,000,000
Outstanding borrowings on revolving credit facility	698,280,000	116,700,000
Line of Credit | Revolving Credit Facility | July 31, 2018
Debt Instrument [Line Items]
Maximum Borrowing Capacity	500,000,000
Outstanding borrowings on revolving credit facility	$ 432,484,000	116,700,000
Weighted Average Interest Rate	5.81%
Line of Credit | Revolving Credit Facility | January 31, 2019
Debt Instrument [Line Items]
Outstanding borrowings on revolving credit facility	$ 265,796,000	$ 0
Weighted Average Interest Rate	5.77%

Debt - Narrative (Detail)

Debt - Narrative (Detail)	Sep. 09, 2019USD ($)d$ / shares	Jun. 28, 2019USD ($)	Jan. 31, 2019period	Jul. 31, 2018	Sep. 30, 2019USD ($)$ / shares	Sep. 30, 2018USD ($)	Jul. 11, 2019USD ($)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Net proceeds used to purchase capped call confirmations					$ 150,530,000	$ 29,414,000
Convertible Debt
Debt Instrument [Line Items]
Unamortized debt discount and debt issuance costs					464,700,000			$ 144,400,000
Debt instrument, face amount issued					1,943,387,000
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity					1,000,000,000
Extension of expiration period (up to)				2 years
Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity					100,000,000
January 31, 2019 | Revolving Credit Facility | Citibank, N.A. | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity					500,000,000
Current borrowing capacity					266,000,000
Credit Agreement | Revolving Credit Facility | Citibank, N.A. | Line of Credit
Debt Instrument [Line Items]
Revolving credit facility, initial term			2 years
Number of additional extension periods | period			2
Additional extension period			6 months
July 31, 2018 | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity					500,000,000
Current borrowing capacity					$ 442,500,000
Revolving credit facility, initial term				1 year
Automatic renewal term				24 months
Portion of financed properties ownership period					180 days
Financed properties ownership period					1 year
June 27, 2020 | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 50,000,000			$ 50,000,000		$ 50,000,000
Revolving credit facility, initial term		1 year
2024 Notes | Convertible Debt
Debt Instrument [Line Items]
Unamortized debt discount and debt issuance costs					2,100,000
Debt instrument, face amount issued	$ 600,000,000				$ 600,000,000
Debt instrument, interest rate stated percentage	0.75%				0.75%
Net proceeds from issuance	$ 592,200,000
Net proceeds used to purchase capped call confirmations	$ 75,200,000
Conversion Price per Share (usd per share) | $ / shares	$ 43.51				$ 43.51
Debt instrument, conversion rate shares	0.0229830
Initial cap price (usd per share) | $ / shares	$ 72.5175
Capped call confirmation premium percentage	125.00%
Debt instrument, convertible threshold percentage	130.00%
Debt instrument, convertible threshold trading days | d	20
Debt instrument, threshold consecutive trading days | d	30
Equity component of issuance of senior notes					$ 163,600,000
2024 Notes | Convertible Debt | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Repurchase price percentage of principal amount	100.00%
2024 Notes | Convertible Debt | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Repurchase price percentage of principal amount	100.00%
2026 Notes | Convertible Debt
Debt Instrument [Line Items]
Unamortized debt discount and debt issuance costs					2,300,000
Debt instrument, face amount issued	$ 500,000,000				$ 500,000,000
Debt instrument, interest rate stated percentage	1.375%				1.375%
Net proceeds from issuance	$ 493,500,000
Net proceeds used to purchase capped call confirmations	$ 75,400,000
Conversion Price per Share (usd per share) | $ / shares	$ 43.51				$ 43.51
Debt instrument, conversion rate shares	0.0229830
Initial cap price (usd per share) | $ / shares	$ 80.5750
Capped call confirmation premium percentage	150.00%
Debt instrument, convertible threshold percentage	130.00%
Debt instrument, convertible threshold trading days | d	20,000
Debt instrument, threshold consecutive trading days | d	30,000
Equity component of issuance of senior notes					$ 172,300,000
2026 Notes | Convertible Debt | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Repurchase price percentage of principal amount	100.00%
2026 Notes | Convertible Debt | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Repurchase price percentage of principal amount	100.00%

Debt - Schedule of Warehouse Li

Debt - Schedule of Warehouse Lines of Credit (Details) - USD ($)	Sep. 30, 2019	Jul. 11, 2019	Jun. 28, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Warehouse lines of credit	$ 30,116,000			$ 33,018,000
Line of Credit
Debt Instrument [Line Items]
Maximum Borrowing Capacity	100,000,000
Warehouse lines of credit	30,116,000			33,017,000
Line of Credit | July 15, 2019
Debt Instrument [Line Items]
Maximum Borrowing Capacity	50,000,000
Warehouse lines of credit	$ 0			14,125,000
Weighted Average Interest Rate	4.89%
Line of Credit | June 27, 2020
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 50,000,000	$ 50,000,000	$ 50,000,000
Warehouse lines of credit	$ 30,116,000			$ 18,892,000
Weighted Average Interest Rate	4.51%

Debt - Schedule of Convertible

Debt - Schedule of Convertible Senior Notes (Detail) - Convertible Debt - USD ($)	Sep. 30, 2019	Sep. 09, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 1,943,387,000
Fair Value	1,844,427,000		$ 784,799,000
September 1, 2026
Debt Instrument [Line Items]
Aggregate Principal Amount	500,000,000	$ 500,000,000
Fair Value	$ 469,375,000		0
Stated Interest Rate	1.375%	1.375%
Effective Interest Rate	8.10%
September 1, 2024
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 600,000,000	$ 600,000,000
Fair Value	$ 573,900,000		0
Stated Interest Rate	0.75%	0.75%
Effective Interest Rate	7.67%
July 1, 2023
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 373,750,000
Fair Value	$ 328,818,000		321,855,000
Stated Interest Rate	1.50%
Effective Interest Rate	6.99%
December 1, 2021
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 460,000,000
Fair Value	$ 455,492,000		446,200,000
Stated Interest Rate	2.00%
Effective Interest Rate	7.44%
December 15, 2020
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 9,637,000
Fair Value	$ 16,842,000		$ 16,744,000
Stated Interest Rate	2.75%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Schedule Of Income Tax [Line Items]
Income tax benefit	$ 1,300	$ 14,700	$ 8,000	$ 3,800	$ 22,700
Income tax benefit calculated using estimate of annual effective tax rate				1,900
Annual effective tax rate					4.30%
Loss before income taxes	$ 65,949	15,192		$ 207,951	$ 44,876
Discrete income tax benefit, stock compensation windfall deduction					20,800
Discrete tax benefit adjustment		$ 3,300			$ 5,900
Federal
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards						$ 1,081,700
State
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards						$ 32,500

Share-Based Awards - Summary of

Share-Based Awards - Summary of Option Award (Detail) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Number of Shares Subject to Existing Options
Beginning Balance (in shares) | shares	27,310,110
Granted (in shares) | shares	7,401,975
Exercised (in shares) | shares	(1,891,111)
Forfeited or cancelled (in shares) | shares	(1,840,756)
Ending Balance (in shares) | shares	30,980,218	27,310,110
Vested and exercisable ending balance (in shares) | shares	18,305,093
Weighted- Average Exercise Price Per Share
Beginning Balance (usd per share) | $ / shares	$ 34.04
Granted (usd per share) | $ / shares	39.52
Exercised (usd per share) | $ / shares	21.69
Forfeited or cancelled (usd per share) | $ / shares	41.36
Ending Balance (usd per share) | $ / shares	35.67	$ 34.04
Vested and exercisable (usd per share) | $ / shares	$ 32.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-Average Remaining Contractual Life, Outstanding	6 years 4 months 13 days	6 years 2 months 23 days
Weighted-Average Remaining Contractual Life, Vested and exercisable	4 years 9 months 10 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Aggregate Intrinsic Value, Outstanding | $	$ 59,722	$ 97,941
Aggregate Intrinsic Value Vested, and exercisable | $	$ 55,130

Share-Based Awards - Fair Value

Share-Based Awards - Fair Value of Options Granted, Estimated at Date of Grant Using Black Scholes Merton Option Pricing Model (Detail) - Option Awards - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	45.00%	42.00%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate	1.61%	2.84%
Weighted-average expected life	5 years	4 years 6 months
Weighted-average fair value of options granted (usd per share)	$ 14.15	$ 19.21	$ 16.55	$ 20.89
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility			45.00%	42.00%
Risk-free interest rate			1.61%	2.52%
Weighted-average expected life			4 years 9 months	4 years 6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility			47.00%	45.00%
Risk-free interest rate			2.53%	2.84%
Weighted-average expected life			5 years 3 months	5 years

Share-Based Awards - Option Awa

Share-Based Awards - Option Awards - Additional Information (Detail) $ in Millions	Sep. 30, 2019USD ($)
Option Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized cost of unvested share-based compensation awards	$ 193

Share-Based Awards - Summary _2

Share-Based Awards - Summary of Restricted Stock Units Activity (Detail) - Restricted Stock Units	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Restricted Stock Units
Beginning balance (in shares) | shares	5,266,324
Granted (in shares) | shares	4,492,544
Vested (in shares) | shares	(1,633,962)
Forfeited or cancelled (in shares) | shares	(933,917)
Ending balance (in shares) | shares	7,190,989
Weighted- Average Grant- Date Fair Value
Unvested outstanding, beginning balance (usd per share) | $ / shares	$ 42.19
Granted (usd per share) | $ / shares	37.79
Vested (usd per share) | $ / shares	40.41
Forfeited or cancelled (usd per share) | $ / shares	41.38
Unvested outstanding, ending balance (usd per share) | $ / shares	$ 39.95

Share-Based Awards - Restricted

Share-Based Awards - Restricted Stock Units - Additional Information (Detail) $ in Millions	Sep. 30, 2019USD ($)
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 265.6

Share-Based Awards - Effects of

Share-Based Awards - Effects of Share Based Compensation in Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	Feb. 21, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		$ 42,128	$ 41,682	$ 151,884	$ 111,366
Chief Executive Officer
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation				26,400
Accelerated vesting period from departure date	18 months
Exercisable period from final date	90 days
Minimum | Chief Executive Officer
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Expected volatility	46.00%
Risk-free interest rate	2.47%
Weighted-average expected life	3 years 10 months 2 days
Maximum | Chief Executive Officer
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Expected volatility	47.00%
Risk-free interest rate	2.49%
Weighted-average expected life	5 years 3 months
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		1,062	969	2,878	3,180
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		6,588	5,911	19,039	17,413
Technology and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		18,034	15,031	51,942	40,920
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		$ 16,444	$ 19,771	$ 78,025	$ 49,853

Net Loss Per Share - Antidiluti

Net Loss Per Share - Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 09, 2019
September 1, 2026 | Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion Spread (in shares)			11,492
Conversion Price per Share (usd per share)	$ 43.51		$ 43.51		$ 43.51
September 1, 2024 | Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion Spread (in shares)			13,790
Conversion Price per Share (usd per share)	43.51		$ 43.51		$ 43.51
July 1, 2023 | Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion Spread (in shares)			4,769
Conversion Price per Share (usd per share)	78.37		$ 78.37
December 1, 2021 | Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion Spread (in shares)			8,785
Conversion Price per Share (usd per share)	$ 52.36		$ 52.36
Class A Common Stock and Class C Capital Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	26,288	27,248	26,508	28,809
Class A Common Stock and Class C Capital Stock | Weighted Average | Option Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	18,900	21,766	19,394	23,508
Class A Common Stock and Class C Capital Stock | Weighted Average | Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	6,964	5,072	6,690	4,891
Class A Common Stock | December 15, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	424	410	424	410

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Jun. 20, 2017USD ($)	Feb. 09, 2017USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)	Feb. 28, 2018claim	Feb. 05, 2018claim	Sep. 30, 2017claim
Other Commitments [Line Items]
Outstanding letters of credit			$ 16,900,000
Outstanding surety bonds			10,100,000	$ 8,900,000
VHT Vs Zillow Group Inc.
Other Commitments [Line Items]
Jury awarded damages	$ 4,100,000
VHT Vs Zillow Group Inc. | Actual Damages
Other Commitments [Line Items]
Jury awarded damages		$ 79,875
VHT Vs Zillow Group Inc. | Statutory Damages
Other Commitments [Line Items]
Jury awarded damages		$ 8,200,000
Class Action Lawsuits
Other Commitments [Line Items]
Number of pending claims | claim							2
Shareholder Derivative Lawsuits
Other Commitments [Line Items]
Number of pending claims | claim					4	2
Homes under contract to purchase that have not closed
Other Commitments [Line Items]
Value of homes under contract that have not closed			$ 221,100,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Affiliated Entity | Charter Service Agreement
Related Party Transaction [Line Items]
Expense recognized pursuant to the Charter Service Agreement	$ 0.1	$ 0.3

Self-Insurance - Additional Inf

Self-Insurance - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Insurance [Abstract]
Percentage of cumulative medical claim under self insurance plan (percent exceeded)	125.00%
Limit of medical claim under self insurance plan (limit)	$ 1,000,000
Minimum amount of individual claim under self insurance plan	500,000
Liability for self-insured claims included in accrued compensation and benefits	$ 3,600,000	$ 3,900,000

Employee Benefit Plan - Additio

Employee Benefit Plan - Additional Information (Detail) - Zillow Merger - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Contribution Plan Disclosure [Line Items]
Company's contribution based on employee contribution (up to)			4.00%
Company's expense related to its defined contribution 401(k) retirement plans	$ 5.6	$ 4.1	$ 15.7	$ 11.9

Segment Information and Reven_3

Segment Information and Revenue - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2019Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information and Reven_4

Segment Information and Revenue - Revenue Categories (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Total revenue		$ 745,208	$ 343,094	$ 1,798,890	$ 968,219
Costs and expenses:
Cost of revenue	[1]	399,835	36,672	822,404	86,118
Sales and marketing		181,347	128,734	530,367	413,752
Technology and development		123,974	105,314	352,074	299,623
General and administrative		88,493	70,743	267,106	187,395
Impairment costs		0	10,000	0	10,000
Acquisition-related costs		0	1,405	0	2,064
Integration costs		5	523	650	523
Total costs and expenses		793,654	353,391	1,972,601	999,475
Loss from operations		(48,446)	(10,297)	(173,711)	(31,256)
Other income		8,999	7,773	27,625	13,308
Interest expense		(26,502)	(12,668)	(61,865)	(26,928)
Loss before income taxes		(65,949)	(15,192)	(207,951)	(44,876)
Homes
Revenue:
Total revenue		384,626	11,018	762,022	11,018
Costs and expenses:
Cost of revenue	[1]	370,796	10,226	733,947	10,312
Sales and marketing		49,186	4,650	107,457	7,035
Technology and development		20,651	6,128	51,130	12,154
General and administrative		22,174	6,010	54,339	11,964
Impairment costs		0	0	0	0
Acquisition-related costs		0	0	0	0
Integration costs		0	0	0	0
Total costs and expenses		462,807	27,014	946,873	41,465
Loss from operations		(78,181)	(15,996)	(184,851)	(30,447)
Other income		0	0	0	0
Interest expense		(9,689)	(432)	(19,346)	(432)
Loss before income taxes		(87,870)	(16,428)	(204,197)	(30,879)
Homes | Homes
Revenue:
Total revenue		384,626	11,018	762,022	11,018
Homes | Premier Agent
Revenue:
Total revenue		0	0	0	0
Homes | Rentals
Revenue:
Total revenue		0	0	0	0
Homes | Other
Revenue:
Total revenue		0	0	0	0
Homes | Mortgages
Revenue:
Total revenue		0	0	0	0
IMT
Revenue:
Total revenue		335,290	313,638	957,231	900,435
Costs and expenses:
Cost of revenue	[1]	24,318	25,186	74,628	72,070
Sales and marketing		118,514	117,522	380,608	384,241
Technology and development		94,656	93,930	276,886	270,978
General and administrative		55,749	60,678	181,270	163,303
Impairment costs		0	10,000	0	10,000
Acquisition-related costs		0	0	0	27
Integration costs		0	0	0	0
Total costs and expenses		293,237	307,316	913,392	900,619
Loss from operations		42,053	6,322	43,839	(184)
Other income		0	0	0	0
Interest expense		0	0	0	0
Loss before income taxes		42,053	6,322	43,839	(184)
IMT | Homes
Revenue:
Total revenue		0	0	0	0
IMT | Premier Agent
Revenue:
Total revenue		240,698	232,703	690,394	677,320
IMT | Rentals
Revenue:
Total revenue		44,430	37,319	124,938	99,670
IMT | Other
Revenue:
Total revenue		50,162	43,616	141,899	123,445
IMT | Mortgages
Revenue:
Total revenue		0	0	0	0
Mortgages
Revenue:
Total revenue		25,292	18,438	79,637	56,766
Costs and expenses:
Cost of revenue	[1]	4,721	1,260	13,829	3,736
Sales and marketing		13,647	6,562	42,302	22,476
Technology and development		8,667	5,256	24,058	16,491
General and administrative		10,570	4,055	31,497	12,128
Impairment costs		0	0	0	0
Acquisition-related costs		0	1,405	0	2,037
Integration costs		5	523	650	523
Total costs and expenses		37,610	19,061	112,336	57,391
Loss from operations		(12,318)	(623)	(32,699)	(625)
Other income		344	0	1,059	0
Interest expense		(280)	0	(668)	0
Loss before income taxes		(12,254)	(623)	(32,308)	(625)
Mortgages | Homes
Revenue:
Total revenue		0	0	0	0
Mortgages | Premier Agent
Revenue:
Total revenue		0	0	0	0
Mortgages | Rentals
Revenue:
Total revenue		0	0	0	0
Mortgages | Other
Revenue:
Total revenue		0	0	0	0
Mortgages | Mortgages
Revenue:
Total revenue		$ 25,292	$ 18,438	$ 79,637	$ 56,766
[1]	Amortization of website development costs and intangible assets included in technology and development of $15,835 and $18,165 for the three months ended September 30, 2019 and 2018, respectively and $44,891 and $61,735 for the nine months ended September 30, 2019 and 2018, respectively.

Segment Information and Reven_5

Segment Information and Revenue - Reconciliation of Segment Gross Profit and Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Loss before income taxes	$ (65,949)	$ (15,192)	$ (207,951)	$ (44,876)
Corporate interest expense	(26,502)	(12,668)	(61,865)	(26,928)
Corporate other income	8,999	7,773	27,625	13,308
Consolidated loss before income taxes	(65,949)	(15,192)	(207,951)	(44,876)
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Loss before income taxes	(58,071)	(10,729)	(192,666)	(31,688)
Consolidated loss before income taxes	(58,071)	(10,729)	(192,666)	(31,688)
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Corporate interest expense	(16,533)	(12,236)	(41,851)	(26,496)
Corporate other income	$ 8,655	$ 7,773	$ 26,566	$ 13,308

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details)	Oct. 21, 2019USD ($)period	Oct. 09, 2019USD ($)	Sep. 09, 2019USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Oct. 29, 2019USD ($)	Oct. 11, 2019USD ($)
Subsequent Event [Line Items]
Net proceeds used to purchase capped call confirmations				$ 150,530,000	$ 29,414,000
Line of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity				100,000,000
Convertible Debt
Subsequent Event [Line Items]
Debt instrument, face amount issued				1,943,387,000
Line of Credit | Revolving Credit Facility
Subsequent Event [Line Items]
Maximum borrowing capacity				$ 1,000,000,000
2024 Notes | Convertible Debt
Subsequent Event [Line Items]
Debt instrument, interest rate stated percentage			0.75%	0.75%
Debt instrument, face amount issued			$ 600,000,000	$ 600,000,000
Net proceeds from the offering			592,200,000
Net proceeds used to purchase capped call confirmations			$ 75,200,000
Subsequent Event | Citibank, N.A. | Zillow Home Loans, LLC
Subsequent Event [Line Items]
Repurchase agreement, maximum amount						$ 75,000,000
Repurchase agreement, initial committed amount						$ 25,000,000
Subsequent Event | 2024 Notes | Convertible Debt
Subsequent Event [Line Items]
Debt instrument, interest rate stated percentage		0.75%
Debt instrument, face amount issued		$ 73,000,000
Net proceeds from the offering		72,000,000
Net proceeds used to purchase capped call confirmations		$ 9,100,000
Subsequent Event | Warehouse Lines of Credit, due October 2019 | Line of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity							$ 50,000,000
Subsequent Event | Credit Agreement | Line of Credit | Revolving Credit Facility | Goldman Sachs Bank USA
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 500,000,000
Revolving credit facility, initial term	2 years
Number of additional extension periods | period	1
Additional extension period	6 months

Uncategorized Items - q32019for

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 40,322,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 40,322,000