Zillow (Z) 10-Q 4 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 27, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-36853
Entity Registrant Name	ZILLOW GROUP, INC.
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
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001617640
Current Fiscal Year End Date	--12-31
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		61,335,992
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		180,104,154

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 3,401,762	$ 1,703,130
Short-term investments	1,294,051	2,218,108
Accounts receivable, net of allowance for doubtful accounts of $3,460 and $3,427 at March 31, 2021 and December 31, 2020, respectively	82,461	69,940
Mortgage loans held for sale		330,758
Inventory	472,397	491,293
Prepaid expenses and other current assets	107,877	75,846
Restricted cash	120,713	75,805
Total current assets	5,753,580	4,964,880
Contract cost assets	50,182	50,719
Property and equipment, net	190,234	196,152
Right of use assets	180,610	187,960
Goodwill	1,984,907	1,984,907
Intangible assets, net	87,711	94,767
Other assets	8,678	7,175
Total assets	8,255,902	7,486,560
Current liabilities:
Accounts payable	17,044	18,974
Accrued expenses and other current liabilities	121,692	94,487
Accrued compensation and benefits	49,844	47,666
Borrowings under credit facilities	662,175	670,209
Deferred revenue	54,192	48,995
Lease liabilities, current portion	28,465	28,310
Total current liabilities	933,412	908,641
Lease liabilities, net of current portion	200,762	207,723
Convertible senior notes	1,597,205	1,613,523
Other long-term liabilities	14,485	14,857
Total liabilities	2,745,864	2,744,744
Commitments and contingencies (Note 16)
Shareholders’ equity:
Preferred stock, $0.0001 par value; 30,000,000 shares authorized; no shares issued and outstanding	0	0
Additional paid-in capital	6,596,850	5,880,883
Accumulated other comprehensive income	454	164
Accumulated deficit	(1,087,291)	(1,139,255)
Total shareholders’ equity	5,510,038	4,741,816
Total liabilities and shareholders’ equity	8,255,902	7,486,560
Level 2
Current assets:
Mortgage loans held for sale	274,319
Restricted cash	0	0
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	$ 18	$ 17

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Allowance for doubtful accounts	$ 3,460	$ 3,427
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)	61,335,992	61,101,303
Common stock, outstanding (in shares)	61,335,992	61,101,303
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)	179,754,423	173,207,170
Common stock, outstanding (in shares)	179,754,423	173,207,170

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Revenue:
Revenue		$ 1,218,440	$ 1,125,821
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	687,030	761,672
Sales and marketing		193,593	204,648
Technology and development		148,856	134,918
General and administrative		100,551	92,285
Impairment costs		0	76,800
Acquisition-related costs		817	0
Total costs and expenses		1,130,847	1,270,323
Income (loss) from operations		87,593	(144,502)
Loss on extinguishment of debt		(1,403)	0
Other income		2,439	9,593
Interest expense		(39,555)	(37,592)
Income (loss) before income taxes		49,074	(172,501)
Income tax benefit		2,890	9,228
Net income (loss)		$ 51,964	$ (163,273)
Net income (loss) per share:
Basic (usd per share)		$ 0.21	$ (0.78)
Diluted (usd per share)		$ 0.20	$ (0.78)
Weighted-average shares outstanding:
Basic (in shares)		243,234	210,674
Diluted (in shares)		259,346	210,674
Homes segment
Revenue:
Revenue		$ 704,152	$ 769,873
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	640,618	732,199
Sales and marketing		55,025	71,589
Technology and development		37,139	32,538
General and administrative		25,532	23,421
Impairment costs		0	0
Acquisition-related costs		0	0
Total costs and expenses		758,314	859,747
Income (loss) from operations		(54,162)	(89,874)
Other income		0	0
Interest expense		(4,312)	(8,084)
Income (loss) before income taxes		(58,474)	(97,958)
IMT
Revenue:
Revenue		446,328	330,666
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	28,016	24,318
Sales and marketing		113,298	120,173
Technology and development		101,893	95,028
General and administrative		58,729	58,754
Impairment costs		0	73,900
Acquisition-related costs		817	0
Total costs and expenses		302,753	372,173
Income (loss) from operations		143,575	(41,507)
Other income		0	0
Interest expense		0	0
Income (loss) before income taxes		143,575	(41,507)
Mortgages segment
Revenue:
Revenue		67,960	25,282
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	18,396	5,155
Sales and marketing		25,270	12,886
Technology and development		9,824	7,352
General and administrative		16,290	10,110
Impairment costs		0	2,900
Acquisition-related costs		0	0
Total costs and expenses		69,780	38,403
Income (loss) from operations		(1,820)	(13,121)
Other income		1,732	202
Interest expense		(1,732)	(226)
Income (loss) before income taxes		$ (1,820)	$ (13,145)
[1]	____________________

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Amortization of website development costs and intangible assets included in technology and development	$ 12,900	$ 11,800
Technology and Development
Amortization of website development costs and intangible assets included in technology and development	$ 20,838	$ 17,184

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 51,964	$ (163,273)
Other comprehensive income:
Unrealized gains on investments	261	3,602
Reclassification adjustment for net investment gains included in net income (loss)	0	434
Net unrealized gains on investments	261	4,036
Currency translation adjustments	29	(90)
Total other comprehensive income	290	3,946
Comprehensive income (loss)	$ 52,254	$ (159,327)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	2.75% convertible senior notes due 2020	Class A Common Stock, Class B Common Stock and Class C Capital Stock	Class A Common Stock, Class B Common Stock and Class C Capital Stock2.75% convertible senior notes due 2020	Additional Paid-In Capital	Additional Paid-In Capital2.75% convertible senior notes due 2020	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning Balance at Dec. 31, 2019	$ 3,435,421		$ 21		$ 4,412,200		$ (977,140)	$ 340
Beginning Balance (in shares) at Dec. 31, 2019			209,066,855,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	92,202		$ 1		92,201
Issuance of common and capital stock upon exercise of stock options (in shares)			3,207,375,000
Vesting of restricted stock units (in shares)			638,909,000
Share-based compensation expense	47,465				47,465
Net income (loss)	(163,273)						(163,273)
Other comprehensive income	3,946							3,946
Ending Balance at Mar. 31, 2020	3,415,761		$ 22		4,551,866		(1,140,413)	4,286
Ending Balance (in shares) at Mar. 31, 2020			212,913,139,000
Beginning Balance at Dec. 31, 2020	4,741,816		$ 24		5,880,883		(1,139,255)	164
Beginning Balance (in shares) at Dec. 31, 2020			240,525,920
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	$ 61,149		$ 0		61,149
Issuance of common and capital stock upon exercise of stock options (in shares)	1,602,896		1,602,896
Vesting of restricted stock units (in shares)			813,471
Restricted stock units withheld for tax liability (in shares)			(622)
Restricted stock units withheld for tax liability	$ (124)				(124)
Share-based compensation expense	67,386				67,386
Issuance of Class C capital stock in connection with equity offering, net of issuance costs of $6,054	544,558		$ 1		544,557
Issuance of Class C capital stock in connection with equity offering, net of issuance costs (in shares)			3,163,502
Conversion of convertible senior notes		$ 42,999				$ 42,999
Conversion of convertible senior notes (in shares)				1,202,720
Unwind capped call transactions (in shares)			(25)
Net income (loss)	51,964						51,964
Other comprehensive income	290							290
Ending Balance at Mar. 31, 2021	$ 5,510,038		$ 25		$ 6,596,850		$ (1,087,291)	$ 454
Ending Balance (in shares) at Mar. 31, 2021			247,307,862

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Shareholders' Equity (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Statement of Stockholders' Equity [Abstract]
Capital stock, issuance costs	$ 6,054

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net income (loss)	$ 51,964,000	$ (163,273,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization expense	28,899,000	29,026,000
Share-based compensation expense	63,673,000	43,795,000
Amortization of right of use assets	7,350,000	6,465,000
Amortization of contract cost assets	10,130,000	8,415,000
Amortization of debt discount and debt issuance costs	25,271,000	22,547,000
Loss on extinguishment of debt	1,403,000	0
Impairment costs	0	76,800,000
Deferred income taxes	(2,890,000)	(9,228,000)
Loss on disposal of property and equipment and other assets	4,418,000	1,952,000
Credit loss expense	128,000	558,000
Net loss on investment securities	0	434,000
Amortization (accretion) of bond premium (discount)	4,014,000	(473,000)
Changes in operating assets and liabilities:
Accounts receivable	(12,649,000)	(5,335,000)
Mortgage loans held for sale	56,439,000	(341,000)
Inventory	18,893,000	302,593,000
Prepaid expenses and other assets	(28,643,000)	(2,916,000)
Contract cost assets	(9,593,000)	(9,771,000)
Lease liabilities	(6,806,000)	(1,625,000)
Accounts payable	(2,235,000)	7,673,000
Accrued expenses and other current liabilities	24,889,000	4,588,000
Accrued compensation and benefits	2,178,000	(4,967,000)
Deferred revenue	5,197,000	(4,400,000)
Other long-term liabilities	(372,000)	(527,000)
Net cash provided by operating activities	241,658,000	301,990,000
Investing activities
Proceeds from maturities of investments	920,304,000	296,272,000
Proceeds from sales of investments	0	53,997,000
Purchases of investments	0	(58,459,000)
Purchases of property and equipment	(11,485,000)	(32,966,000)
Purchases of intangible assets	(4,485,000)	(4,503,000)
Net cash provided by investing activities	904,334,000	254,341,000
Financing activities
Proceeds from issuance of Class C capital stock, net of issuance costs	544,557,000	0
Proceeds from borrowings on credit facilities	126,010,000	34,460,000
Repayments of borrowings on credit facilities	(88,340,000)	(294,150,000)
Net borrowings (repayments) on warehouse line of credit and repurchase agreements	(45,704,000)	4,386,000
Proceeds from exercise of stock options	61,149,000	92,202,000
Value of equity awards withheld for tax liability	(124,000)	0
Net cash provided by (used in) financing activities	597,548,000	(163,102,000)
Net increase in cash, cash equivalents and restricted cash during period	1,743,540,000	393,229,000
Cash, cash equivalents and restricted cash at beginning of period	1,778,935,000	1,230,909,000
Cash, cash equivalents and restricted cash at end of period	3,522,475,000	1,624,138,000
Supplemental disclosures of cash flow information
Cash paid for interest	14,191,000	17,038,000
Noncash transactions:
Capitalized share-based compensation	3,713,000	3,670,000
Write-off of fully depreciated property and equipment	11,603,000	4,143,000
Write-off of fully amortized intangible assets	1,300,000	0
Property and equipment purchased on account	$ 905,000	$ 9,445,000

Organization and Description of

Organization and Description of Business	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Organization and Description of Business	Organization and Description of Business Zillow Group, Inc. is reimagining real estate to make it easier to unlock life’s next chapter. As the most visited real estate website in the United States, Zillow and its affiliates offer customers an on-demand experience for selling, buying, renting or financing with transparency and nearly seamless end-to-end service. Zillow Offers buys and sells homes directly in dozens of markets across the country, allowing sellers control over their timeline. Zillow Home Loans, our affiliate lender, provides our customers with an easy option to get pre-approved and secure financing for their next home purchase. In September 2020, Zillow launched Zillow Homes, Inc., a licensed brokerage entity, to streamline Zillow Offers transactions. Other consumer brands include Trulia, StreetEasy, HotPads and Out East. In addition, Zillow Group provides a comprehensive suite of marketing software and technology solutions which include 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”), and upon the closing of the Trulia acquisition in February 2015, each of Zillow, Inc. and Trulia became wholly owned subsidiaries of Zillow Group, Inc. 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: public health crises, like the COVID-19 pandemic and the availability and widespread distribution and use of effective vaccines; rates of revenue growth; our ability to successfully integrate and realize the benefits of our past or future strategic acquisitions or investments; the satisfaction of conditions precedent to the closing of our proposed acquisition of ShowingTime.com, Inc., including expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Act; 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; actual or anticipated changes to our products and services; 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; 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	3 Months Ended
	Mar. 31, 2021
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, 2020, which was filed with the SEC on February 12, 2021. The condensed consolidated balance sheet as of December 31, 2020, 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 March 31, 2021 and our results of operations, comprehensive income (loss), shareholders’ equity and cash flows for the three months ended March 31, 2021 and 2020. The results for the three months ended March 31, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021 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 accounting for certain revenue offerings, 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, share-based compensation, income taxes, business combinations and the recoverability of goodwill, among others. To the extent there are material differences between these estimates, judgments or assumptions and actual results, our financial statements will be affected. The COVID-19 pandemic has introduced significant additional uncertainty with respect to estimates, judgments and assumptions, which may materially impact the estimates previously listed, among others. Recently Adopted Accounting Standards In December 2019, the Financial Accounting Standards Board (“FASB”) issued guidance which is intended to simplify the accounting for income taxes. It removes certain exceptions to the general principles and clarifies and amends existing guidance to improve consistent application. This guidance is effective for interim and annual periods beginning after December 15, 2020, and early adoption is permitted. We adopted this guidance on January 1, 2021. The method of adoption for this guidance varies based on the amendment, however the relevant amendments have been applied on a prospective basis. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows. Recently Issued Accounting Standards Not Yet Adopted In August 2020, the FASB issued guidance which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts in an entity’s own equity. Among other changes, the guidance removes the liability and equity separation models for convertible instruments. Instead, entities will account for convertible debt instruments wholly as debt unless convertible instruments contain features that require bifurcation as a derivative or that result in substantial premiums accounted for as paid-in capital. The guidance also requires the application of the if-converted method to calculate the impact of convertible instruments on diluted earnings per share. The guidance is effective for fiscal years beginning after December 15, 2021, with early adoption permitted for fiscal years beginning after December 15, 2020, and can be adopted on either a retrospective or modified retrospective basis. We expect to adopt this guidance on January 1, 2022. Although we continue to evaluate the method of adoption and impact of this guidance on our financial position, results of operations and cash flows, upon adoption we expect this guidance to result in a reclassification of conversion feature balances from additional paid-in capital to debt and to decrease reported interest expense for our convertible senior notes. In March 2020, the FASB issued guidance which provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference the London Inter-Bank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued because of reference rate reform. This guidance is optional for a limited period of time to ease the potential burden in accounting for, or recognizing the effects of, reference rate reform on financial reporting. This guidance is effective from March 12, 2020 through December 31, 2022. Entities may elect to adopt the amendments for contract modifications as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. We expect to apply some of the expedients and exceptions provided in this guidance to our credit facilities, warehouse line of credit and master repurchase agreements, all of which reference the one-month LIBOR in the applicable interest rate, as publication of the one-month LIBOR is expected to cease after June 30, 2023. We expect to amend our facility agreements prior to that date. As the goal of the reference rate reform transition is for it to be economically neutral to entities, we do not believe the adoption of this guidance will have a material impact on our financial position, results of operations or cash flows.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements 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 (Level 1). The fair value measurement of other cash equivalents is based on observable market-based inputs principally derived from or corroborated by observable market data (Level 2). 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 (Level 2). Restricted cash — The carrying value of restricted cash approximates fair value due to the short period of time amounts borrowed on the credit facilities are outstanding and amounts are held in escrow (Level 1). 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 (Level 2). 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. Since not all IRLCs will become closed loans, we adjust our fair value measurements for the estimated amount of IRLCs that will not close. This adjustment is effected through the pull-through rate, which represents the probability that an interest rate lock commitment will ultimately result in a closed loan (Level 3). The following table presents the range and weighted-average pull-through rates used in determining the fair value of IRLCs as of the dates presented: March 31, 2021 December 31, 2020 Range 50% - 100% 47% - 100% Weighted-average 81% 75% 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 economic hedging instruments are calculated by reference to quoted prices for similar assets (Level 2). 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): March 31, 2021 Total Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 3,074,175 $ 3,074,175 $ — $ — Short-term investments: U. S. government agency securities 988,774 — 988,774 — Treasury bills 298,984 — 298,984 — Municipal securities 6,044 — 6,044 — Certificates of deposit 249 — 249 — Restricted cash 120,713 120,713 — — Mortgage origination-related: Mortgage loans held for sale 274,319 — 274,319 — IRLCs 5,002 — — 5,002 Forward contracts - other current assets 4,946 — 4,946 — Forward contracts - other current liabilities (16) — (16) — Total $ 4,773,190 $ 3,194,888 $ 1,573,300 $ 5,002 December 31, 2020 Total Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 1,486,384 $ 1,486,384 $ — $ — Municipal securities 3,228 — 3,228 — Short-term investments: Treasury bills 1,163,813 — 1,163,813 — U. S. government agency securities 1,037,577 — 1,037,577 — Municipal securities 16,220 — 16,220 — Certificates of deposit 498 — 498 — Restricted cash 75,805 75,805 — — Mortgage origination-related: Mortgage loans held for sale 330,758 — 330,758 — IRLCs 12,342 — — 12,342 Forward contracts - other current liabilities (2,608) — (2,608) — Total $ 4,124,017 $ 1,562,189 $ 2,549,486 $ 12,342 The following table presents the changes in our IRLCs during the three months ended March 31, 2021 (in thousands): Three Months Ended Three Months Ended Balance, beginning of the period $ 12,342 $ 937 Issuances 18,301 5,208 Transfers (24,398) (5,349) Fair value changes recognized in earnings (1,243) 1,429 Balance, end of period $ 5,002 $ 2,225 At March 31, 2021, the notional amounts of the hedging instruments related to our mortgage loans held for sale were $336.2 million and $560.0 million for our IRLCs and forward contracts, respectively. At December 31, 2020, the notional amounts of the hedging instruments related to our mortgage loans held for sale were $378.1 million and $652.1 million for our IRLCs and forward contracts, respectively. We do not have the right to offset our derivative positions. See Note 11 for the carrying amount and estimated fair value of our convertible senior notes.

Cash and Cash Equivalents, Shor

Cash and Cash Equivalents, Short-term Investments and Restricted Cash	3 Months Ended
	Mar. 31, 2021
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, short-term investments and restricted cash as of the dates presented (in thousands): March 31, 2021 Amortized Gross Gross Estimated Cash $ 327,587 $ — $ — $ 327,587 Cash equivalents: Money market funds 3,074,175 — — 3,074,175 Short-term investments: U. S. government agency securities 988,478 303 (7) 988,774 Treasury bills 298,953 31 — 298,984 Municipal securities 6,046 — (2) 6,044 Certificates of deposit 249 — — 249 Restricted cash 120,713 — — 120,713 Total $ 4,816,201 $ 334 $ (9) $ 4,816,526 December 31, 2020 Amortized Gross Gross Estimated Cash $ 213,518 $ — $ — $ 213,518 Cash equivalents: Money market funds 1,486,384 — — 1,486,384 Municipal securities 3,229 — (1) 3,228 Short-term investments: Treasury bills 1,163,748 65 — 1,163,813 U.S. government agency securities 1,037,572 57 (52) 1,037,577 Municipal securities 16,226 — (6) 16,220 Certificates of deposit 498 — — 498 Restricted cash 75,805 — — 75,805 Total $ 3,996,980 $ 122 $ (59) $ 3,997,043 All short-term investments as of March 31, 2021 have a contractual maturity date of one year or less.

Inventory

Inventory	3 Months Ended
	Mar. 31, 2021
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): March 31, 2021 December 31, 2020 Finished goods $ 341,887 $ 339,372 Work-in-process 130,510 151,921 Inventory $ 472,397 $ 491,293

Contract Balances

Contract Balances	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Contract Balances	Contract Balances Contract assets were $34.3 million and $20.8 million as of March 31, 2021 and December 31, 2020, respectively. Contract assets are recorded within prepaids and other current assets in our condensed consolidated balance sheets. For the three months ended March 31, 2021 and 2020, we recognized revenue of $46.5 million and $36.0 million, respectively, that was included in the deferred revenue balance at the beginning of the related period.

Contract Cost Assets

Contract Cost Assets	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Contract Cost Assets	Contract Balances Contract assets were $34.3 million and $20.8 million as of March 31, 2021 and December 31, 2020, respectively. Contract assets are recorded within prepaids and other current assets in our condensed consolidated balance sheets. For the three months ended March 31, 2021 and 2020, we recognized revenue of $46.5 million and $36.0 million, respectively, that was included in the deferred revenue balance at the beginning of the related period.

Property and Equipment, net

Property and Equipment, net	3 Months Ended
	Mar. 31, 2021
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): March 31, 2021 December 31, 2020 Website development costs $ 110,971 $ 95,466 Leasehold improvements 102,632 110,280 Office equipment, furniture and fixtures 34,561 39,607 Construction-in-progress 32,553 44,151 Computer equipment 20,209 20,433 Property and equipment 300,926 309,937 Less: accumulated amortization and depreciation (110,692) (113,785) Property and equipment, net $ 190,234 $ 196,152 We recorded depreciation expense related to property and equipment (other than website development costs) of $7.9 million and $11.8 million during the three months ended March 31, 2021 and 2020, respectively. We capitalized $12.4 million and $12.5 million in website development costs during the three months ended March 31, 2021 and 2020, respectively. Amortization expense for website development costs included in technology and development expenses was $8.0 million and $5.4 million during the three months ended March 31, 2021 and 2020, respectively.

Equity Investment

Equity Investment	3 Months Ended
	Mar. 31, 2021
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment	Equity InvestmentIn October 2016, we purchased a 10% equity interest in a privately held variable interest entity within the real estate industry for $10.0 million. In March 2020, we recognized a non-cash impairment charge of $5.3 million related to this investment. The impairment charge is included in impairment costs within our IMT segment for the three months ended March 31, 2020. We sold our 10% equity interest in June 2020.

Intangible Assets, net

Intangible Assets, net	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets, net	Intangible Assets, net The following tables present the detail of intangible assets as of the dates presented (in thousands): March 31, 2021 Cost Accumulated Net Trade names and trademarks $ 36,500 $ (5,105) $ 31,395 Software 33,764 (13,155) 20,609 Developed technology 86,064 (73,507) 12,557 Customer relationships 87,600 (76,429) 11,171 Intangibles-in-progress 9,886 — 9,886 Purchased content 49,565 (47,472) 2,093 Total $ 303,379 $ (215,668) $ 87,711 December 31, 2020 Cost Accumulated Net Trade names and trademarks $ 36,500 $ (3,822) $ 32,678 Software 28,515 (11,483) 17,032 Developed technology 86,064 (70,270) 15,794 Customer relationships 87,600 (73,301) 14,299 Intangibles-in-progress 11,863 — 11,863 Purchased content 47,930 (44,829) 3,101 Total $ 298,472 $ (203,705) $ 94,767 Amortization expense recorded for intangible assets for the three months ended March 31, 2021 and 2020 was $12.9 million and $11.8 million, respectively. These amounts are included in technology and development expenses. We did not record any impairment costs related to our intangible assets for the three months ended March 31, 2021. During the three months ended March 31, 2020, we recognized a non-cash impairment charge of $71.5 million related to our Trulia trade names and trademarks intangible asset, which historically had not been subject to amortization. The impairment charge is included in impairment costs within our IMT and Mortgages segments. In March 2020, we identified factors directly related to the COVID-19 pandemic that led us to conclude it was more likely than not that the $108.0 million carrying value of the asset exceeded its fair value. Accordingly, with the assistance of a third-party valuation specialist, we performed a quantitative analysis to determine the fair value of the intangible asset and concluded that our best estimate of its fair value was $36.5 million. The remaining carrying value of the intangible asset will be amortized on an accelerated basis commensurate with the projected cash flows expected to be generated by the intangible asset over a useful life of 10 years. The carrying value of the Trulia trade names and trademarks intangible asset was $31.4 million and $32.7 million as of March 31, 2021 and December 31, 2020, respectively. For additional details regarding this impairment, see Note 11 in the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2020.

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt	Debt The following table presents the carrying values of Zillow Group’s debt as of the dates presented (in thousands): March 31, 2021 December 31, 2020 Homes segment Credit facilities: Goldman Sachs Bank USA $ 190,176 $ 145,825 Citibank, N.A. 109,732 87,103 Credit Suisse AG, Cayman Islands 98,928 128,238 Total Homes segment debt 398,836 361,166 Mortgages segment Repurchase agreements: Credit Suisse AG, Cayman Islands 132,001 149,913 Citibank, N.A. 50,546 90,227 Warehouse line of credit: Comerica Bank 80,792 68,903 Total Mortgages segment debt 263,339 309,043 Convertible senior notes 1.375% convertible senior notes due 2026 352,077 347,566 2.75% convertible senior notes due 2025 421,770 414,888 0.75% convertible senior notes due 2024 493,044 524,273 1.50% convertible senior notes due 2023 330,314 326,796 Total convertible senior notes 1,597,205 1,613,523 Total debt $ 2,259,380 $ 2,283,732 Homes Segment To provide capital for Zillow Offers, we utilize credit facilities that are classified as current liabilities in our condensed consolidated balance sheets. We classify these credit facilities as current liabilities as amounts drawn to purchase homes are typically due as homes are sold, which we expect to be within one year. The following table summarizes certain details related to our credit facilities (in thousands, except interest rates): Lender Final Maturity Date Maximum Borrowing Capacity Weighted-Average Interest Rate Goldman Sachs Bank USA April 20, 2022 $ 500,000 3.15 % Citibank, N.A. November 30, 2021 500,000 2.86 % Credit Suisse AG, Cayman Islands December 31, 2022 500,000 2.86 % Total $ 1,500,000 On January 6, 2021, certain wholly owned subsidiaries of Zillow Group amended the Credit Suisse AG, Cayman Islands credit agreement previously maturing on July 31, 2021 such that it now matures on December 31, 2022. Undrawn amounts available under the credit facilities included in the table above are not committed, meaning the applicable lender is not committed to, but may in its discretion, advance loan funds in excess of the outstanding borrowings. The final maturity dates are inclusive of extensions which are subject to agreement by the respective lender. On February 23, 2021, certain wholly owned subsidiaries of Zillow Group amended and restated the Citibank, N.A. credit agreement in order to facilitate a titling trust structure. In March 2021, Zillow Group, through Zillow Offers, began buying and selling homes through a titling trust. The titling trust facilitates the allocation of beneficial ownership of properties to special purpose entities (each, an “SPE”), which special purpose entities are then party to agreements to finance the properties. Zillow Group initially formed these SPEs to purchase and sell residential properties through Zillow Offers, and subsequent to the creation of the titling trust, these SPEs hold beneficial interests in homes purchased by the titling trust, which the SPEs subsequently finance. 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. The credit facilities are secured by the assets and equity of one or more SPEs. These SPEs and titling trust are variable interest entities and Zillow Group is the primary beneficiary as it has the power to control the activities that most significantly impact the SPEs’ and titling trust’s economic performance and the obligation to absorb losses of the SPEs and titling trust or the right to receive benefits that could potentially be significant to the SPEs and titling trust. The SPEs and titling trust are consolidated within Zillow Group’s condensed consolidated financial statements. As of March 31, 2021 and December 31, 2020, the total assets of the SPEs and titling trust were $573.6 million and $551.2 million, respectively, of which $471.9 million and $491.3 million are inventory, respectively, $83.2 million and $53.0 million are restricted cash, respectively, and $16.4 million and $3.9 million are accounts receivable, respectively. As of March 31, 2021 and December 31, 2020, the total liabilities of the SPEs and titling trust were $411.6 million and $372.5 million, respectively, of which $398.8 million and $361.2 million are credit facility borrowings, respectively, and $9.9 million and $10.8 million are accrued expenses, respectively. Outstanding amounts drawn under each credit facility are required to be repaid on the facility maturity 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. Continued inclusion of properties in each credit facility is subject to various eligibility criteria. For example, aging criteria limit the inclusion in the borrowing base of properties owned longer than a specified number of days, and properties owned for longer than one year are generally ineligible. The stated interest rate on our credit facilities is one-month LIBOR plus an applicable margin, and in certain cases include a LIBOR floor, as defined in the respective credit agreements. Our credit facilities include customary representations and warranties, provisions regarding events of default and covenants. The terms of these credit facilities and related financing documents require Zillow Group and certain of its subsidiaries, as applicable, to comply with a number of customary financial and other covenants, such as maintaining certain levels of liquidity, tangible net worth and leverage ratios. As of March 31, 2021, Zillow Group was in compliance with all financial covenants and no event of default had occurred. Except for certain limited circumstances, the credit facilities are non-recourse to Zillow Group. Our credit facilities require that we establish, maintain and in certain circumstances that Zillow Group fund specified reserve accounts. These reserve accounts include, but are not limited to, interest reserves, insurance reserves, 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. Mortgages Segment To provide capital for Zillow Home Loans, we utilize master repurchase agreements and a warehouse line of credit which are classified as current liabilities in our condensed consolidated balance sheets. The repurchase agreements and warehouse line of credit provide short-term financing between the issuance of a mortgage loan and when Zillow Home Loans sells the loan to an investor or directly to an agency. The following table summarizes certain details related to our repurchase agreements and warehouse line of credit (in thousands, except interest rates): Lender Maturity Date Maximum Borrowing Capacity Weighted-Average Interest Rate Credit Suisse AG, Cayman Islands March 18, 2022 $ 300,000 2.50 % Citibank, N.A. October 26, 2021 100,000 1.86 % Comerica Bank June 26, 2021 100,000 3.01 % Total $ 500,000 On March 19, 2021, Zillow Home Loans amended its Credit Suisse AG, Cayman Islands (“Credit Suisse”) master repurchase agreement to increase the uncommitted total maximum borrowing capacity to $300.0 million with a maturity date of March 18, 2022. The repurchase agreement with Citibank, N.A. includes a committed amount of $25.0 million. In accordance with the master repurchase agreements, Credit Suisse and Citibank, N.A. (together the “Lenders”) have agreed to pay Zillow Home Loans a negotiated purchase price for eligible loans, and Zillow Home Loans has simultaneously agreed to repurchase such loans from the Lenders under a specified timeframe at an agreed upon price that includes interest. The master repurchase agreements contain margin call provisions that provide the Lenders with certain rights in the event of a decline in the market value of the assets purchased under the master repurchase agreements. As of March 31, 2021 and December 31, 2020, $189.9 million and $240.1 million, respectively, in mortgage loans held for sale were pledged as collateral under the master repurchase agreements. On February 4, 2021, Zillow Home Loans amended its Comerica Bank warehouse line of credit to increase the total maximum borrowing capacity to $100.0 million with a maturity date of June 26, 2021. The warehouse line of credit with Comerica Bank is committed. Borrowings on the repurchase agreements and warehouse line of credit bear interest at the one-month LIBOR plus an applicable margin, and in certain cases include a LIBOR floor, as defined in the governing agreements, and are secured by residential mortgage loans held for sale. The repurchase agreements and warehouse line of credit include customary representations and warranties, covenants and provisions regarding events of default. As of March 31, 2021, Zillow Home Loans was in compliance with all financial covenants and no event of default had occurred. The repurchase agreements and warehouse line of credit are recourse to Zillow Home Loans, and have no recourse to Zillow Group or any of its other subsidiaries. For additional details related to our warehouse line of credit and repurchase agreements, see Note 14 in the Notes to the Consolidated Financial Statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2020. Convertible Senior Notes The following tables summarize certain details related to our outstanding convertible senior notes as of the dates presented or for the periods ended (in thousands, except interest rates): March 31, 2021 December 31, 2020 Maturity Date Aggregate Principal Amount Stated Interest Rate Effective Interest Rate First Interest Payment Date Semi-Annual Interest Payment Dates Unamortized Debt Discount and Debt Issuance Costs Fair Value Unamortized Debt Discount and Debt Issuance Costs Fair Value September 1, 2026 $ 498,800 1.375 % 8.10 % March 1, 2020 March 1; September 1 $ 146,723 $ 1,476,837 $ 152,434 $ 1,508,675 May 15, 2025 565,000 2.75 % 10.32 % November 15, 2020 May 15; November 15 143,230 1,172,674 150,112 1,168,855 September 1, 2024 622,382 0.75 % 7.69 % March 1, 2020 March 1; September 1 129,338 1,854,113 148,727 2,023,280 July 1, 2023 372,825 1.50 % 6.99 % January 1, 2019 January 1; July 1 42,511 611,522 46,954 633,039 Total $ 2,059,007 $ 461,802 $ 5,115,146 $ 498,227 $ 5,333,849 Three Months Ended Three Months Ended Maturity Date Contractual Coupon Interest Amortization of Debt Discount Amortization of Debt Issuance Costs Interest Expense Contractual Coupon Interest Amortization of Debt Discount Amortization of Debt Issuance Costs Interest Expense September 1, 2026 $ 1,717 $ 5,226 $ 128 $ 7,071 $ 1,719 $ 4,824 $ 118 $ 6,661 May 15, 2025 3,884 6,533 349 10,766 — — — — September 1, 2024 1,238 8,410 289 9,937 1,248 7,861 267 9,376 July 1, 2023 1,401 3,950 386 5,737 1,402 3,697 361 5,460 December 1, 2021 — — — — 2,300 4,911 508 7,719 December 15, 2020 — — — — 66 — — 66 Total $ 8,240 $ 24,119 $ 1,152 $ 33,511 $ 6,735 $ 21,293 $ 1,254 $ 29,282 The convertible notes are senior unsecured obligations and are classified as long-term debt in our condensed consolidated balance sheets based on their contractual maturity dates. Interest on the convertible notes is paid semi-annually in arrears. 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 2026 (“2026 Notes”), 2025 (“2025 Notes”), 2024 (“2024 Notes”) and 2023 (“2023 Notes”) (together, the “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 Notes will mature on their respective maturity date, unless earlier repurchased, redeemed or converted in accordance with their terms. The following table summarizes the conversion and redemption options with respect to the Notes: Maturity Date Early Conversion Date Conversion Rate Conversion Price Optional Redemption Date September 1, 2026 March 1, 2026 22.9830 $ 43.51 September 5, 2023 May 15, 2025 November 15, 2024 14.8810 67.20 May 22, 2023 September 1, 2024 March 1, 2024 22.9830 43.51 September 5, 2022 July 1, 2023 April 1, 2023 12.7592 78.37 July 6, 2021 The following table summarizes certain details related to the capped call confirmations with respect to certain of the convertible senior notes: Maturity Date Initial Cap Price Cap Price Premium September 1, 2026 $ 80.5750 150 % September 1, 2024 72.5175 125 % July 1, 2023 105.45 85 % December 1, 2021 69.19 85 % Each series of the Notes was convertible during the three months ended March 31, 2021, at the option of the holders. The following table summarizes the conversion activity for the Notes for the period presented (in thousands, except for share amounts): Three Months Ended 2023 Notes 2024 Notes 2026 Notes Total Aggregate principal amount converted $ 925 $ 50,618 $ 1,200 $ 52,743 Shares of Class C capital stock issued upon conversion 11,789 1,163,352 27,579 1,202,720 Total fair value of consideration transferred (1) $ 1,643 $ 153,925 $ 4,204 $ 159,772 Loss on extinguishment of debt: Consideration allocated to the liability component (2) $ 841 $ 41,267 $ 883 $ 42,991 Carrying value of the liability component, net of unamortized debt discount and debt issuance costs 818 39,927 843 41,588 Loss on extinguishment of debt $ 23 $ 1,340 $ 40 $ 1,403 Consideration allocated to the equity component $ 802 $ 112,658 $ 3,321 $ 116,781 (1) Total fair value of consideration transferred includes the value of shares transferred to note holders using the daily volume weighted-average price of our Class C capital stock on the conversion date and an immaterial amount of cash paid in lieu of fractional shares. (2) Consideration allocated to the liability component is based on the fair value of the liability component immediately prior to settlement, which was calculated using a discounted cash flow analysis with a market interest rate of a similar liability that does not have an associated convertible feature. For more than 20 trading days during the 30 consecutive trading days ended March 31, 2021, the last reported sale price of our Class C capital stock exceeded 130% of the conversion price of each series of the Notes. Accordingly, each series of the Notes is convertible at the option of the holders from April 1 through June 30, 2021. The 2026 Notes and 2024 Notes were first convertible during the three months ended September 30, 2020, and the 2025 Notes and 2023 Notes were first convertible during the three months ended March 31, 2021. For additional details related to our convertible senior notes, 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, 2020.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We are subject to federal and state income taxes in the U.S. and federal and provincial income taxes in Canada. As of March 31, 2021 and December 31, 2020, 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 $1.7 billion as of December 31, 2020, which are available to reduce future taxable income. We have accumulated state tax losses of approximately $53.2 million (tax effected) as of December 31, 2020. We recorded an income tax benefit of $2.9 million for the three months ended March 31, 2021, primarily related to state income taxes. We recorded an income tax benefit of $9.2 million for the three months ended March 31, 2020 primarily as a result of a $9.7 million income tax benefit related to the $71.5 million non-cash impairment we recorded during the three months ended March 31, 2020 related to the Trulia trade names and trademarks intangible asset. For additional information about the non-cash impairment, see Note 10 of our condensed consolidated financial statements.

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity Preferred Stock Our board of directors has the authority to fix and determine and to amend the number of shares of any series of preferred stock that is wholly unissued or to be established and to fix and determine and to amend the designation, preferences, voting powers and limitations and the relative, participating, optional or other rights, of any series of shares of preferred stock that is wholly unissued or to be established, subject in each case to certain approval rights of holders of our outstanding Class B common stock. There was no preferred stock issued and outstanding as of March 31, 2021 or December 31, 2020. Common and Capital Stock Our Class A common stock has no preferences or privileges and is not redeemable. Holders of Class A common stock are entitled to one vote for each share. Our Class B common stock has no preferences or privileges and is not redeemable. At any time after the date of issuance, each share of Class B common stock, at the option of the holder, may be converted into one share of Class A common stock, or automatically converted into Class A common stock upon the affirmative vote by or written consent of holders of a majority of the shares of the Class B common stock. Holders of Class B common stock are entitled to 10 votes for each share. Our Class C capital stock has no preferences or privileges, is not redeemable and, except in limited circumstances, is non-voting. Equity Distribution Agreement On February 17, 2021, we entered into an equity distribution agreement with certain sales agents and/or principals (the “Managers”), pursuant to which we may offer and sell from time to time, through the Managers, shares of our Class C capital stock, having an aggregate gross sales price of up to $1.0 billion, in such share amounts as we may specify by notice to the Managers, in accordance with the terms and conditions set forth in the equity distribution agreement. The following table summarizes the activity pursuant to the equity distribution agreement for the period presented (in thousands, except share and per share amounts): Three Months Ended Shares of Class C capital stock issued 3,163,502 Weighted-average issuance price per share $ 174.0511 Gross proceeds (1) $ 550,611 (1) Net proceeds were $544.6 million after deducting $6.1 million of commissions and other offering expenses incurred.

Share-Based Awards

Share-Based Awards	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Share-Based Awards	Share-Based Awards Option Awards The following table summarizes option award activity for the three months ended March 31, 2021: Number Weighted- Weighted- Aggregate Outstanding at January 1, 2021 20,051,051 $ 42.68 7.22 $ 1,751,105 Granted 8,226,833 133.88 Exercised (1,602,896) 38.15 Forfeited or cancelled (373,388) 47.58 Outstanding at March 31, 2021 26,301,600 71.41 7.99 1,580,222 Vested and exercisable at March 31, 2021 9,411,270 39.23 6.05 851,494 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 2021 2020 Expected volatility 52%-55% 45%-48% Expected dividend yield — — Risk-free interest rate 0.57%-0.90% 0.87%-0.93% Weighted-average expected life 4.50-5.75 years 5.00-5.50 years Weighted-average fair value of options granted $59.74 $20.75 As of March 31, 2021, there was a total of $638.0 million in unrecognized compensation cost related to unvested stock options. Restricted Stock Units The following table summarizes activity for restricted stock units for the three months ended March 31, 2021: Restricted Weighted- Unvested outstanding at January 1, 2021 7,316,557 $ 48.14 Granted 930,831 138.13 Vested (813,471) 44.96 Forfeited (162,972) 48.73 Unvested outstanding at March 31, 2021 7,270,945 60.01 As of March 31, 2021, there was a total of $411.1 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 2021 2020 Cost of revenue $ 2,386 $ 1,173 Sales and marketing 9,887 6,993 Technology and development 26,393 18,917 General and administrative 25,007 16,712 Total $ 63,673 $ 43,795

Net Income (Loss) Per Share

Net Income (Loss) Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Net Income (Loss) Per Share Basic net income (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares (including Class A common stock, Class B common stock and Class C capital stock) outstanding during the period. In the calculation of basic net income (loss) per share, undistributed earnings are allocated assuming all earnings during the period were distributed. Diluted net income (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares (including Class A common stock, Class B common stock and Class C capital stock) outstanding during the period and potentially dilutive Class A common stock and Class C capital stock equivalents, except in cases where the effect of the Class A common stock or Class C capital stock equivalent would be antidilutive. Potential Class A common stock and Class C capital stock equivalents consist of Class A common stock and Class C capital stock issuable upon exercise of stock options and Class A common stock and Class C capital stock underlying unvested restricted stock units using the treasury stock method. Potential Class A common stock equivalents also include Class A common stock issuable upon conversion of the convertible notes due in 2020 using the if-converted method through the date of their last conversion in December 2020. Prior to the second half of 2020, we intended to settle the principal amount of our outstanding convertible senior notes in cash and therefore used the treasury stock method to calculate any potential dilutive effect of the conversion spread on diluted net income per share, if applicable. Effective July 1, 2020, we can no longer assume cash settlement of the principal amount of these outstanding convertible notes, therefore share settlement is now presumed. On a prospective basis we have applied the if-converted method for calculating any potential dilutive effect of the conversion of the outstanding convertible notes on diluted net income per share, if applicable. The following table presents the maximum number of shares and conversion price per share of Class C capital stock for each of the Notes based on the aggregate principal amount outstanding as of March 31, 2021 (in thousands, except per share amounts): Maturity Date Shares Conversion Price per Share September 1, 2026 11,464 $ 43.51 May 15, 2025 8,408 67.20 September 1, 2024 14,304 43.51 July 1, 2023 4,757 78.37 For the periods presented, the following table reconciles the denominators used in the basic and diluted net income (loss) per share calculations (in thousands): Three Months Ended March 31, 2021 2020 Denominator for basic calculation 243,234 210,674 Effect of dilutive securities: Option awards 12,437 — Unvested restricted stock units 3,675 — Denominator for dilutive calculation 259,346 210,674 For the periods presented, the following Class A common stock and Class C capital stock equivalents were excluded from the calculations of diluted net income (loss) per share because their effect would have been antidilutive (in thousands): Three Months Ended 2021 2020 Weighted-average Class A common stock and Class C capital stock option awards outstanding 2,546 23,663 Weighted-average Class C capital stock restricted stock units outstanding 303 7,623 Class A common stock issuable upon conversion of the convertible notes maturing in 2020 — 407 Class C capital stock issuable upon conversion of the 2023 Notes, 2024 Notes, 2025 Notes and 2026 Notes 39,834 — Total Class A common stock and Class C capital stock equivalents 42,683 31,693

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Interest Rate Lock Commitments We have entered into IRLCs with prospective borrowers under our mortgage origination business whereby we commit to lend a certain loan amount under specific terms and at a specific interest rate to the borrower. These commitments are treated as derivatives and are carried at fair value. For additional information regarding our IRLCs, see Note 3 of our Notes to Condensed Consolidated Financial Statements of this Quarterly Report on Form 10-Q. 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 2021 and 2030. For additional information regarding our lease agreements, see Note 13 in the Notes to the Consolidated Financial Statements in our Annual Report on Form 10-K for the fiscal year ended December 31, 2020. Purchase Commitments Purchase commitments primarily include various non-cancelable agreements to purchase content related to our mobile applications and websites and certain cloud computing services 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 March 31, 2021, the value of homes under contract that have not closed was $511.3 million. Letters of Credit As of March 31, 2021, 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 $10.4 million and $10.1 million, respectively, as of March 31, 2021 and December 31, 2020. 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 March 31, 2021 or December 31, 2020. 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. On February 9, 2017, a jury trial 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. On June 20, 2017, the District Court granted certain of our post-trial 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 we 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 U.S. Supreme Court denied VHT’s petition for writ of certiorari seeking review of certain rulings by the Ninth Circuit Court of Appeals. On December 6, 2019, the Company filed a motion for summary judgment with the District Court seeking a ruling that VHT’s images are a compilation, or in the alternative, seeking a dismissal of the case based on a recent U.S. Supreme Court ruling. On May 8, 2020, the District Court denied the Company’s motion for summary judgment and granted VHT’s motion for summary judgment on the issue of whether the remaining photos were a compilation. On March 10, 2021, the District Court ordered a new trial relating to 2,700 images that the jury previously found that the Company had willfully infringed, and for which the court did not enter judgment, on the question of (i) whether the Company’s infringement was innocent, and (2) statutory damages. A trial date has been scheduled during the third quarter of 2021. We do not believe there is a reasonable possibility that a material loss will be incurred related to this lawsuit. 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 purported 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 which was granted by the District Court on October 28, 2020. On February 17, 2021, the Ninth Circuit Court of Appeals denied our petition for review of that decision. We have denied the allegations of wrongdoing and intend to vigorously defend the claims in this lawsuit. We do not believe that there is a reasonable possibility that a material loss will be incurred related to this lawsuit. 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 federal 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. On February 28, 2020, our motion to dismiss the consolidated federal shareholder derivative complaint was denied. On May 18, 2020, we filed an answer in the consolidated federal derivative lawsuit. On August 24, 2020, we filed an answer in the consolidated state derivative matter. On February 16, 2021, the court in the consolidated state derivative matter stayed the action. On March 5, 2021, a new shareholder derivative lawsuit was filed in the U.S. District Court for the Western District of Washington 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, alleging, among other things, violations of federal securities laws. The defendants intend to deny the allegations of wrongdoing and vigorously defend the claims in this lawsuit. We do not believe that there is a reasonable possibility that a material loss will be incurred related to these derivative matters. On September 17, 2019, International Business Machines Corporation (“IBM”) filed a complaint against us in the U.S. 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. On November 8, 2019, we filed a motion to transfer venue and/or to dismiss the complaint. On December 2, 2019, IBM filed an amended complaint, and on December 16, 2019, we filed a renewed motion to transfer venue and/or to dismiss the complaint. The Company’s motion to transfer venue to the U.S. District Court for the Western District of Washington was granted on May 28, 2020. We filed our answer with counterclaims in response to the amended complaint on June 11, 2020. On July 2, 2020, IBM filed a motion to dismiss our counterclaims. In response to IBM’s motion, on July 22, 2020, we filed an amended answer with counterclaims. On August 12, 2020, IBM filed its answer to our counterclaims. On September 18, 2020, we filed four inter partes review (“IPR”) petitions before the U.S. Patent and Trial Appeal Board (“PTAB”) seeking the Board’s review of the patentability with respect to three of the patents asserted by IBM in the lawsuit. On March 15, 2021, the PTAB instituted inter partes review proceedings with respect to two of the three patents for which we filed petitions. On March 22, 2021, the PTAB denied institution with respect to the last of the three patents for which we filed an IPR. On April 21, 2021, we filed a request for rehearing of the PTAB decision denying institution. On January 22, 2021, the court partially stayed the action with respect to all patents for which we filed an IPR and set forth a motion schedule. On March 8, 2021, IBM filed its second amended complaint. On March 25, 2021, we filed an amended motion for judgment on the pleadings. 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 these IBM complaints; however, the possible loss or range of loss is not estimable. On July 21, 2020, IBM filed a second action against us in the U.S. District Court for the Western District of Washington, alleging, among other things that the Company has infringed and continues to willfully infringe five patents held by IBM and seeks unspecified damages. On September 14, 2020, we filed a motion to dismiss the complaint filed in the action, to which IBM responded by the filing of an amended complaint on November 5, 2020. On December 18, 2020, we filed a motion to dismiss IBM’s first amended complaint. On December 23, 2020, the Court issued a written order staying this case in full. 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 these IBM complaints; 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.

Employee Benefit Plan

Employee Benefit Plan	3 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit PlanWe 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 $7.7 million and $6.4 million, respectively, for the three months ended March 31, 2021 and 2020.

Segment Information and Revenue

Segment Information and Revenue	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Segment Information and Revenue	Segment Information and Revenue 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 Homes, Internet, Media & Technology (“IMT”) and Mortgages segments. The Homes segment includes the financial results from Zillow Group’s purchase and sale of homes directly through Zillow Offers and the financial results from title and escrow services through Zillow Closing Services. 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 Mortgages segment primarily includes financial results for mortgage originations and the sale of mortgages on the secondary market through Zillow Home Loans and advertising sold to mortgage lenders and other mortgage professionals. 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, costs related to operating our mobile applications and websites, 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 income (loss) before income taxes by segment. This information is included in the following table for the periods presented (in thousands): Three Months Ended Three Months Ended Homes IMT Mortgages Homes IMT Mortgages Revenue: Zillow Offers $ 700,974 $ — $ — $ 769,112 $ — $ — Premier Agent — 334,318 — — 242,106 — Other 3,178 112,010 — 761 88,560 — Mortgages — — 67,960 — — 25,282 Total revenue 704,152 446,328 67,960 769,873 330,666 25,282 Costs and expenses: Cost of revenue 640,618 28,016 18,396 732,199 24,318 5,155 Sales and marketing 55,025 113,298 25,270 71,589 120,173 12,886 Technology and development 37,139 101,893 9,824 32,538 95,028 7,352 General and administrative 25,532 58,729 16,290 23,421 58,754 10,110 Impairment costs — — — — 73,900 2,900 Acquisition-related costs — 817 — — — — Total costs and expenses (1) 758,314 302,753 69,780 859,747 372,173 38,403 Income (loss) from operations (54,162) 143,575 (1,820) (89,874) (41,507) (13,121) Segment other income — — 1,732 — — 202 Segment interest expense (4,312) — (1,732) (8,084) — (226) Income (loss) before income taxes (2) $ (58,474) $ 143,575 $ (1,820) $ (97,958) $ (41,507) $ (13,145) (1) The following table presents depreciation and amortization expense and share-based compensation expense for each of our segments for the periods presented (in thousands): Three Months Ended Three Months Ended Homes IMT Mortgages Homes IMT Mortgages Depreciation and amortization expense $ 4,293 $ 22,799 $ 1,807 $ 3,575 $ 23,777 $ 1,674 Share-based compensation expense $ 15,921 $ 41,392 $ 6,360 $ 11,304 $ 29,547 $ 2,944 (2) The following table presents the reconciliation of total segment income (loss) before income taxes to consolidated income (loss) before income taxes for the periods presented (in thousands): Three Months Ended 2021 2020 Total segment income (loss) before income taxes $ 83,281 $ (152,610) Corporate interest expense (33,511) (29,282) Corporate other income 707 9,391 Loss on extinguishment of debt (1,403) — Consolidated income (loss) before income taxes $ 49,074 $ (172,501) Certain corporate items are not directly attributable to any of our segments, including the loss on extinguishment of debt, 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	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Acquisition of ShowingTime.com, Inc. As previously disclosed, in February 2021, we entered into a definitive agreement to acquire ShowingTime.com, Inc. (“ShowingTime”), a real estate showing software provider, for $500.0 million in cash, subject to certain adjustments, payable upon the closing of the acquisition. On April 19, 2021, each of Zillow Group and ShowingTime received a request from the U.S. Federal Trade Commission (the “FTC”) for additional information and documentary material (commonly referred to as a “Second Request”) pursuant to the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (the “HSR Act”) in connection with our proposed acquisition of ShowingTime. The FTC’s Second Request extends the waiting period imposed under the HSR Act until 30 days after both Zillow Group and ShowingTime have substantially complied with the Second Request, unless the waiting period is terminated earlier by the FTC or voluntarily extended through an agreement among Zillow Group, ShowingTime and the FTC. We continue to cooperate with the FTC in its review of the proposed acquisition. Amendment of Credit Facility Agreements On April 7, 2021, certain wholly owned subsidiaries of Zillow Group amended and restated the credit agreement with Credit Suisse AG, Cayman Islands, in order to facilitate a titling trust structure. The credit facility will continue to be classified within current liabilities in our condensed consolidated balance sheets. On April 14, 2021, certain wholly owned subsidiaries of Zillow Group amended and restated the credit agreement with Goldman Sachs Bank USA previously maturing on April 20, 2022 in order to facilitate a titling trust structure and extend the maturity date to October 21, 2022. The credit facility will continue to be classified within current liabilities in our condensed consolidated balance sheets.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
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, 2020, which was filed with the SEC on February 12, 2021. The condensed consolidated balance sheet as of December 31, 2020, 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 March 31, 2021 and our results of operations, comprehensive income (loss), shareholders’ equity and cash flows for the three months ended March 31, 2021 and 2020. The results for the three months ended March 31, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021 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 accounting for certain revenue offerings, 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, share-based compensation, income taxes, business combinations and the recoverability of goodwill, among others. To the extent there are material differences between these estimates, judgments or assumptions and actual results, our financial statements will be affected. The COVID-19 pandemic has introduced significant additional uncertainty with respect to estimates, judgments and assumptions, which may materially impact the estimates previously listed, among others.
Recently Adopted Accounting Standards and Recently Issued Accounting Standards Not Yet Adopted	Recently Adopted Accounting Standards In December 2019, the Financial Accounting Standards Board (“FASB”) issued guidance which is intended to simplify the accounting for income taxes. It removes certain exceptions to the general principles and clarifies and amends existing guidance to improve consistent application. This guidance is effective for interim and annual periods beginning after December 15, 2020, and early adoption is permitted. We adopted this guidance on January 1, 2021. The method of adoption for this guidance varies based on the amendment, however the relevant amendments have been applied on a prospective basis. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows. Recently Issued Accounting Standards Not Yet Adopted In August 2020, the FASB issued guidance which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts in an entity’s own equity. Among other changes, the guidance removes the liability and equity separation models for convertible instruments. Instead, entities will account for convertible debt instruments wholly as debt unless convertible instruments contain features that require bifurcation as a derivative or that result in substantial premiums accounted for as paid-in capital. The guidance also requires the application of the if-converted method to calculate the impact of convertible instruments on diluted earnings per share. The guidance is effective for fiscal years beginning after December 15, 2021, with early adoption permitted for fiscal years beginning after December 15, 2020, and can be adopted on either a retrospective or modified retrospective basis. We expect to adopt this guidance on January 1, 2022. Although we continue to evaluate the method of adoption and impact of this guidance on our financial position, results of operations and cash flows, upon adoption we expect this guidance to result in a reclassification of conversion feature balances from additional paid-in capital to debt and to decrease reported interest expense for our convertible senior notes. In March 2020, the FASB issued guidance which provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions that reference the London Inter-Bank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued because of reference rate reform. This guidance is optional for a limited period of time to ease the potential burden in accounting for, or recognizing the effects of, reference rate reform on financial reporting. This guidance is effective from March 12, 2020 through December 31, 2022. Entities may elect to adopt the amendments for contract modifications as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. We expect to apply some of the expedients and exceptions provided in this guidance to our credit facilities, warehouse line of credit and master repurchase agreements, all of which reference the one-month LIBOR in the applicable interest rate, as publication of the one-month LIBOR is expected to cease after June 30, 2023. We expect to amend our facility agreements prior to that date. As the goal of the reference rate reform transition is for it to be economically neutral to entities, we do not believe the adoption of this guidance will have a material impact on our financial position, results of operations or cash flows.
Fair Value Measurements	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 (Level 1). The fair value measurement of other cash equivalents is based on observable market-based inputs principally derived from or corroborated by observable market data (Level 2). 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 (Level 2). Restricted cash — The carrying value of restricted cash approximates fair value due to the short period of time amounts borrowed on the credit facilities are outstanding and amounts are held in escrow (Level 1). 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 (Level 2). 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. Since not all IRLCs will become closed loans, we adjust our fair value measurements for the estimated amount of IRLCs that will not close. This adjustment is effected through the pull-through rate, which represents the probability that an interest rate lock commitment will ultimately result in a closed loan (Level 3). 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 economic hedging instruments are calculated by reference to quoted prices for similar assets (Level 2).
Segment Reporting	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 Homes, Internet, Media & Technology (“IMT”) and Mortgages segments. The Homes segment includes the financial results from Zillow Group’s purchase and sale of homes directly through Zillow Offers and the financial results from title and escrow services through Zillow Closing Services. 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 Mortgages segment primarily includes financial results for mortgage originations and the sale of mortgages on the secondary market through Zillow Home Loans and advertising sold to mortgage lenders and other mortgage professionals. 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, costs related to operating our mobile applications and websites, 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)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurement Inputs and Valuation Techniques	The following table presents the range and weighted-average pull-through rates used in determining the fair value of IRLCs as of the dates presented: March 31, 2021 December 31, 2020 Range 50% - 100% 47% - 100% Weighted-average 81% 75%
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): March 31, 2021 Total Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 3,074,175 $ 3,074,175 $ — $ — Short-term investments: U. S. government agency securities 988,774 — 988,774 — Treasury bills 298,984 — 298,984 — Municipal securities 6,044 — 6,044 — Certificates of deposit 249 — 249 — Restricted cash 120,713 120,713 — — Mortgage origination-related: Mortgage loans held for sale 274,319 — 274,319 — IRLCs 5,002 — — 5,002 Forward contracts - other current assets 4,946 — 4,946 — Forward contracts - other current liabilities (16) — (16) — Total $ 4,773,190 $ 3,194,888 $ 1,573,300 $ 5,002 December 31, 2020 Total Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 1,486,384 $ 1,486,384 $ — $ — Municipal securities 3,228 — 3,228 — Short-term investments: Treasury bills 1,163,813 — 1,163,813 — U. S. government agency securities 1,037,577 — 1,037,577 — Municipal securities 16,220 — 16,220 — Certificates of deposit 498 — 498 — Restricted cash 75,805 75,805 — — Mortgage origination-related: Mortgage loans held for sale 330,758 — 330,758 — IRLCs 12,342 — — 12,342 Forward contracts - other current liabilities (2,608) — (2,608) — Total $ 4,124,017 $ 1,562,189 $ 2,549,486 $ 12,342
Schedule of Changes in IRLCs	The following table presents the changes in our IRLCs during the three months ended March 31, 2021 (in thousands): Three Months Ended Three Months Ended Balance, beginning of the period $ 12,342 $ 937 Issuances 18,301 5,208 Transfers (24,398) (5,349) Fair value changes recognized in earnings (1,243) 1,429 Balance, end of period $ 5,002 $ 2,225

Cash and Cash Equivalents, Sh_2

Cash and Cash Equivalents, Short-term Investments and Restricted Cash (Tables)	3 Months Ended
	Mar. 31, 2021
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, short-term investments and restricted cash as of the dates presented (in thousands): March 31, 2021 Amortized Gross Gross Estimated Cash $ 327,587 $ — $ — $ 327,587 Cash equivalents: Money market funds 3,074,175 — — 3,074,175 Short-term investments: U. S. government agency securities 988,478 303 (7) 988,774 Treasury bills 298,953 31 — 298,984 Municipal securities 6,046 — (2) 6,044 Certificates of deposit 249 — — 249 Restricted cash 120,713 — — 120,713 Total $ 4,816,201 $ 334 $ (9) $ 4,816,526 December 31, 2020 Amortized Gross Gross Estimated Cash $ 213,518 $ — $ — $ 213,518 Cash equivalents: Money market funds 1,486,384 — — 1,486,384 Municipal securities 3,229 — (1) 3,228 Short-term investments: Treasury bills 1,163,748 65 — 1,163,813 U.S. government agency securities 1,037,572 57 (52) 1,037,577 Municipal securities 16,226 — (6) 16,220 Certificates of deposit 498 — — 498 Restricted cash 75,805 — — 75,805 Total $ 3,996,980 $ 122 $ (59) $ 3,997,043

Inventory (Tables)

Inventory (Tables)	3 Months Ended
	Mar. 31, 2021
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): March 31, 2021 December 31, 2020 Finished goods $ 341,887 $ 339,372 Work-in-process 130,510 151,921 Inventory $ 472,397 $ 491,293

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	3 Months Ended
	Mar. 31, 2021
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): March 31, 2021 December 31, 2020 Website development costs $ 110,971 $ 95,466 Leasehold improvements 102,632 110,280 Office equipment, furniture and fixtures 34,561 39,607 Construction-in-progress 32,553 44,151 Computer equipment 20,209 20,433 Property and equipment 300,926 309,937 Less: accumulated amortization and depreciation (110,692) (113,785) Property and equipment, net $ 190,234 $ 196,152

Intangible Assets, net (Tables)

Intangible Assets, net (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	The following tables present the detail of intangible assets as of the dates presented (in thousands): March 31, 2021 Cost Accumulated Net Trade names and trademarks $ 36,500 $ (5,105) $ 31,395 Software 33,764 (13,155) 20,609 Developed technology 86,064 (73,507) 12,557 Customer relationships 87,600 (76,429) 11,171 Intangibles-in-progress 9,886 — 9,886 Purchased content 49,565 (47,472) 2,093 Total $ 303,379 $ (215,668) $ 87,711 December 31, 2020 Cost Accumulated Net Trade names and trademarks $ 36,500 $ (3,822) $ 32,678 Software 28,515 (11,483) 17,032 Developed technology 86,064 (70,270) 15,794 Customer relationships 87,600 (73,301) 14,299 Intangibles-in-progress 11,863 — 11,863 Purchased content 47,930 (44,829) 3,101 Total $ 298,472 $ (203,705) $ 94,767

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Carrying Value of Debt	The following table presents the carrying values of Zillow Group’s debt as of the dates presented (in thousands): March 31, 2021 December 31, 2020 Homes segment Credit facilities: Goldman Sachs Bank USA $ 190,176 $ 145,825 Citibank, N.A. 109,732 87,103 Credit Suisse AG, Cayman Islands 98,928 128,238 Total Homes segment debt 398,836 361,166 Mortgages segment Repurchase agreements: Credit Suisse AG, Cayman Islands 132,001 149,913 Citibank, N.A. 50,546 90,227 Warehouse line of credit: Comerica Bank 80,792 68,903 Total Mortgages segment debt 263,339 309,043 Convertible senior notes 1.375% convertible senior notes due 2026 352,077 347,566 2.75% convertible senior notes due 2025 421,770 414,888 0.75% convertible senior notes due 2024 493,044 524,273 1.50% convertible senior notes due 2023 330,314 326,796 Total convertible senior notes 1,597,205 1,613,523 Total debt $ 2,259,380 $ 2,283,732
Schedule of Revolving Credit Facilities and Lines of Credit	The following table summarizes certain details related to our credit facilities (in thousands, except interest rates): Lender Final Maturity Date Maximum Borrowing Capacity Weighted-Average Interest Rate Goldman Sachs Bank USA April 20, 2022 $ 500,000 3.15 % Citibank, N.A. November 30, 2021 500,000 2.86 % Credit Suisse AG, Cayman Islands December 31, 2022 500,000 2.86 % Total $ 1,500,000 Lender Maturity Date Maximum Borrowing Capacity Weighted-Average Interest Rate Credit Suisse AG, Cayman Islands March 18, 2022 $ 300,000 2.50 % Citibank, N.A. October 26, 2021 100,000 1.86 % Comerica Bank June 26, 2021 100,000 3.01 % Total $ 500,000
Schedule of Convertible Senior Notes	The following tables summarize certain details related to our outstanding convertible senior notes as of the dates presented or for the periods ended (in thousands, except interest rates): March 31, 2021 December 31, 2020 Maturity Date Aggregate Principal Amount Stated Interest Rate Effective Interest Rate First Interest Payment Date Semi-Annual Interest Payment Dates Unamortized Debt Discount and Debt Issuance Costs Fair Value Unamortized Debt Discount and Debt Issuance Costs Fair Value September 1, 2026 $ 498,800 1.375 % 8.10 % March 1, 2020 March 1; September 1 $ 146,723 $ 1,476,837 $ 152,434 $ 1,508,675 May 15, 2025 565,000 2.75 % 10.32 % November 15, 2020 May 15; November 15 143,230 1,172,674 150,112 1,168,855 September 1, 2024 622,382 0.75 % 7.69 % March 1, 2020 March 1; September 1 129,338 1,854,113 148,727 2,023,280 July 1, 2023 372,825 1.50 % 6.99 % January 1, 2019 January 1; July 1 42,511 611,522 46,954 633,039 Total $ 2,059,007 $ 461,802 $ 5,115,146 $ 498,227 $ 5,333,849 Three Months Ended Three Months Ended Maturity Date Contractual Coupon Interest Amortization of Debt Discount Amortization of Debt Issuance Costs Interest Expense Contractual Coupon Interest Amortization of Debt Discount Amortization of Debt Issuance Costs Interest Expense September 1, 2026 $ 1,717 $ 5,226 $ 128 $ 7,071 $ 1,719 $ 4,824 $ 118 $ 6,661 May 15, 2025 3,884 6,533 349 10,766 — — — — September 1, 2024 1,238 8,410 289 9,937 1,248 7,861 267 9,376 July 1, 2023 1,401 3,950 386 5,737 1,402 3,697 361 5,460 December 1, 2021 — — — — 2,300 4,911 508 7,719 December 15, 2020 — — — — 66 — — 66 Total $ 8,240 $ 24,119 $ 1,152 $ 33,511 $ 6,735 $ 21,293 $ 1,254 $ 29,282 The following table summarizes the conversion and redemption options with respect to the Notes: Maturity Date Early Conversion Date Conversion Rate Conversion Price Optional Redemption Date September 1, 2026 March 1, 2026 22.9830 $ 43.51 September 5, 2023 May 15, 2025 November 15, 2024 14.8810 67.20 May 22, 2023 September 1, 2024 March 1, 2024 22.9830 43.51 September 5, 2022 July 1, 2023 April 1, 2023 12.7592 78.37 July 6, 2021 The following table summarizes certain details related to the capped call confirmations with respect to certain of the convertible senior notes: Maturity Date Initial Cap Price Cap Price Premium September 1, 2026 $ 80.5750 150 % September 1, 2024 72.5175 125 % July 1, 2023 105.45 85 % December 1, 2021 69.19 85 % Each series of the Notes was convertible during the three months ended March 31, 2021, at the option of the holders. The following table summarizes the conversion activity for the Notes for the period presented (in thousands, except for share amounts): Three Months Ended 2023 Notes 2024 Notes 2026 Notes Total Aggregate principal amount converted $ 925 $ 50,618 $ 1,200 $ 52,743 Shares of Class C capital stock issued upon conversion 11,789 1,163,352 27,579 1,202,720 Total fair value of consideration transferred (1) $ 1,643 $ 153,925 $ 4,204 $ 159,772 Loss on extinguishment of debt: Consideration allocated to the liability component (2) $ 841 $ 41,267 $ 883 $ 42,991 Carrying value of the liability component, net of unamortized debt discount and debt issuance costs 818 39,927 843 41,588 Loss on extinguishment of debt $ 23 $ 1,340 $ 40 $ 1,403 Consideration allocated to the equity component $ 802 $ 112,658 $ 3,321 $ 116,781 (1) Total fair value of consideration transferred includes the value of shares transferred to note holders using the daily volume weighted-average price of our Class C capital stock on the conversion date and an immaterial amount of cash paid in lieu of fractional shares. (2) Consideration allocated to the liability component is based on the fair value of the liability component immediately prior to settlement, which was calculated using a discounted cash flow analysis with a market interest rate of a similar liability that does not have an associated convertible feature.

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of Sale of Stock	The following table summarizes the activity pursuant to the equity distribution agreement for the period presented (in thousands, except share and per share amounts): Three Months Ended Shares of Class C capital stock issued 3,163,502 Weighted-average issuance price per share $ 174.0511 Gross proceeds (1) $ 550,611 (1) Net proceeds were $544.6 million after deducting $6.1 million of commissions and other offering expenses incurred.

Share-Based Awards (Tables)

Share-Based Awards (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Summary of Option Award Activity	The following table summarizes option award activity for the three months ended March 31, 2021: Number Weighted- Weighted- Aggregate Outstanding at January 1, 2021 20,051,051 $ 42.68 7.22 $ 1,751,105 Granted 8,226,833 133.88 Exercised (1,602,896) 38.15 Forfeited or cancelled (373,388) 47.58 Outstanding at March 31, 2021 26,301,600 71.41 7.99 1,580,222 Vested and exercisable at March 31, 2021 9,411,270 39.23 6.05 851,494
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 2021 2020 Expected volatility 52%-55% 45%-48% Expected dividend yield — — Risk-free interest rate 0.57%-0.90% 0.87%-0.93% Weighted-average expected life 4.50-5.75 years 5.00-5.50 years Weighted-average fair value of options granted $59.74 $20.75
Summary of Restricted Stock Units Activity	The following table summarizes activity for restricted stock units for the three months ended March 31, 2021: Restricted Weighted- Unvested outstanding at January 1, 2021 7,316,557 $ 48.14 Granted 930,831 138.13 Vested (813,471) 44.96 Forfeited (162,972) 48.73 Unvested outstanding at March 31, 2021 7,270,945 60.01
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 2021 2020 Cost of revenue $ 2,386 $ 1,173 Sales and marketing 9,887 6,993 Technology and development 26,393 18,917 General and administrative 25,007 16,712 Total $ 63,673 $ 43,795

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table presents the maximum number of shares and conversion price per share of Class C capital stock for each of the Notes based on the aggregate principal amount outstanding as of March 31, 2021 (in thousands, except per share amounts): Maturity Date Shares Conversion Price per Share September 1, 2026 11,464 $ 43.51 May 15, 2025 8,408 67.20 September 1, 2024 14,304 43.51 July 1, 2023 4,757 78.37 For the periods presented, the following table reconciles the denominators used in the basic and diluted net income (loss) per share calculations (in thousands): Three Months Ended March 31, 2021 2020 Denominator for basic calculation 243,234 210,674 Effect of dilutive securities: Option awards 12,437 — Unvested restricted stock units 3,675 — Denominator for dilutive calculation 259,346 210,674 For the periods presented, the following Class A common stock and Class C capital stock equivalents were excluded from the calculations of diluted net income (loss) per share because their effect would have been antidilutive (in thousands): Three Months Ended 2021 2020 Weighted-average Class A common stock and Class C capital stock option awards outstanding 2,546 23,663 Weighted-average Class C capital stock restricted stock units outstanding 303 7,623 Class A common stock issuable upon conversion of the convertible notes maturing in 2020 — 407 Class C capital stock issuable upon conversion of the 2023 Notes, 2024 Notes, 2025 Notes and 2026 Notes 39,834 — Total Class A common stock and Class C capital stock equivalents 42,683 31,693

Segment Information and Reven_2

Segment Information and Revenue (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Revenue Categories	This information is included in the following table for the periods presented (in thousands): Three Months Ended Three Months Ended Homes IMT Mortgages Homes IMT Mortgages Revenue: Zillow Offers $ 700,974 $ — $ — $ 769,112 $ — $ — Premier Agent — 334,318 — — 242,106 — Other 3,178 112,010 — 761 88,560 — Mortgages — — 67,960 — — 25,282 Total revenue 704,152 446,328 67,960 769,873 330,666 25,282 Costs and expenses: Cost of revenue 640,618 28,016 18,396 732,199 24,318 5,155 Sales and marketing 55,025 113,298 25,270 71,589 120,173 12,886 Technology and development 37,139 101,893 9,824 32,538 95,028 7,352 General and administrative 25,532 58,729 16,290 23,421 58,754 10,110 Impairment costs — — — — 73,900 2,900 Acquisition-related costs — 817 — — — — Total costs and expenses (1) 758,314 302,753 69,780 859,747 372,173 38,403 Income (loss) from operations (54,162) 143,575 (1,820) (89,874) (41,507) (13,121) Segment other income — — 1,732 — — 202 Segment interest expense (4,312) — (1,732) (8,084) — (226) Income (loss) before income taxes (2) $ (58,474) $ 143,575 $ (1,820) $ (97,958) $ (41,507) $ (13,145) (1) The following table presents depreciation and amortization expense and share-based compensation expense for each of our segments for the periods presented (in thousands): Three Months Ended Three Months Ended Homes IMT Mortgages Homes IMT Mortgages Depreciation and amortization expense $ 4,293 $ 22,799 $ 1,807 $ 3,575 $ 23,777 $ 1,674 Share-based compensation expense $ 15,921 $ 41,392 $ 6,360 $ 11,304 $ 29,547 $ 2,944 (2) The following table presents the reconciliation of total segment income (loss) before income taxes to consolidated income (loss) before income taxes for the periods presented (in thousands): Three Months Ended 2021 2020 Total segment income (loss) before income taxes $ 83,281 $ (152,610) Corporate interest expense (33,511) (29,282) Corporate other income 707 9,391 Loss on extinguishment of debt (1,403) — Consolidated income (loss) before income taxes $ 49,074 $ (172,501)
Reconciliation of Segment Gross Profit and Loss	The following table presents the reconciliation of total segment income (loss) before income taxes to consolidated income (loss) before income taxes for the periods presented (in thousands): Three Months Ended 2021 2020 Total segment income (loss) before income taxes $ 83,281 $ (152,610) Corporate interest expense (33,511) (29,282) Corporate other income 707 9,391 Loss on extinguishment of debt (1,403) — Consolidated income (loss) before income taxes $ 49,074 $ (172,501)

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Measurement Inputs and Valuation Techniques (Details) - IRLCs - Not Designated as Hedging Instrument	Mar. 31, 2021	Dec. 31, 2020
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value rates, IRLCs	0.50	0.47
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value rates, IRLCs	1	1
Weighted-average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value rates, IRLCs	0.81	0.75

Fair Value Measurements - Fai_2

Fair Value Measurements - Fair Value of Cash Equivalents and Investments (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	$ 120,713	$ 75,805
Mortgage loans held for sale	274,319	330,758
Fair Value, Net Asset (Liability), Total	4,773,190	4,124,017
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	120,713	75,805
Mortgage loans held for sale	0	0
Fair Value, Net Asset (Liability), Total	3,194,888	1,562,189
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	0	0
Mortgage loans held for sale	274,319	330,758
Fair Value, Net Asset (Liability), Total	1,573,300	2,549,486
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	0	0
Mortgage loans held for sale	0	0
Fair Value, Net Asset (Liability), Total	5,002	12,342
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,074,175	1,486,384
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		1,486,384
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		3,228
Short-term investments	6,044	16,220
Municipal securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
Municipal securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		3,228
Short-term investments		16,220
Municipal securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0
Short-term investments	0	0
U. S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	988,774	1,037,577
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		1,037,577
U. S. government agency securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	298,984	1,163,813
Treasury bills | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Treasury bills | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		1,163,813
Treasury bills | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	249	498
Certificates of deposit | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Certificates of deposit | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		498
Certificates of deposit | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
IRLCs | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	5,002	12,342
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	0	0
IRLCs | Level 3 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	5,002	12,342
Forward contracts | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	4,946
Derivative liability	(16)	(2,608)
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
Derivative liability	0	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	4,946
Derivative liability	(16)	(2,608)
Forward contracts | Level 3 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Derivative liability	$ 0	$ 0

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Changes in IRLCs (Details) - IRLCs - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Asset, Rollforward [Roll Forward]
Balance, beginning of the period	$ 12,342	$ 937
Issuances	18,301	5,208
Transfers	(24,398)	(5,349)
Fair value changes recognized in earnings	(1,243)	1,429
Balance, end of period	$ 5,002	$ 2,225

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Mortgage Loans Held For Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	$ 336.2	$ 378.1
IRLCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	$ 560	$ 652.1

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	Mar. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 3,401,762	$ 1,703,130
Short-term investments:
Gross Unrealized Gains	334	122
Gross Unrealized Losses	(9)	(59)
Restricted cash	120,713	75,805
Cash, cash equivalents, short-term investments, and restricted cash, amortized cost	4,816,201	3,996,980
Cash, cash equivalents, short-term investments, and restricted cash, estimated fair market value	4,816,526	3,997,043
U. S. government agency securities
Short-term investments:
Amortized Cost	988,478
Gross Unrealized Gains	303
Gross Unrealized Losses	(7)
Estimated Fair Market Value	988,774	1,037,577
Treasury bills
Short-term investments:
Amortized Cost	298,953	1,163,748
Gross Unrealized Gains	31	65
Gross Unrealized Losses	0	0
Estimated Fair Market Value	298,984	1,163,813
U.S. government agency securities
Short-term investments:
Amortized Cost		1,037,572
Gross Unrealized Gains		57
Gross Unrealized Losses		(52)
Estimated Fair Market Value		1,037,577
Municipal securities
Short-term investments:
Amortized Cost	6,046	16,226
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2)	(6)
Estimated Fair Market Value	6,044	16,220
Certificates of deposit
Short-term investments:
Amortized Cost	249	498
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	249	498
Cash
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	327,587	213,518
Money market funds
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 3,074,175	1,486,384
Municipal securities
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents, at cost		3,229
Cash and cash equivalents, gross unrealized losses		(1)
Cash and cash equivalents		$ 3,228

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Finished goods	$ 341,887	$ 339,372
Work-in-process	130,510	151,921
Inventory	$ 472,397	$ 491,293

Contract Balances (Details)

Contract Balances (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Contract asset	$ 34.3		$ 20.8
Revenue recognized, recorded in deferred revenue as of prior period	$ 46.5	$ 36

Contract Cost Assets (Details)

Contract Cost Assets (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Contract cost assets	$ 50,182,000		$ 50,719,000
Impairment of contract cost assets	0	$ 0
Capitalized contract cost, amortization	$ 10,130,000	$ 8,415,000

Property and Equipment, net - D

Property and Equipment, net - Detail of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment	$ 300,926	$ 309,937
Less: accumulated amortization and depreciation	(110,692)	(113,785)
Property and equipment, net	190,234	196,152
Website development costs
Property, Plant and Equipment [Line Items]
Property and equipment	110,971	95,466
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	102,632	110,280
Office equipment, furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	34,561	39,607
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property and equipment	32,553	44,151
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	$ 20,209	$ 20,433

Property and Equipment, net - A

Property and Equipment, net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Property, Plant and Equipment [Line Items]
Amortization and depreciation expense related to property and equipment other than website development costs	$ 7.9	$ 11.8
Capitalization of website development costs	12.4	12.5
Amortization of website development costs and intangible assets included in technology and development	12.9	11.8
Technology and development | Software Development
Property, Plant and Equipment [Line Items]
Amortization of website development costs and intangible assets included in technology and development	$ 8	$ 5.4

Equity Investment - Narrative (

Equity Investment - Narrative (Detail) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Oct. 31, 2016	Mar. 31, 2021	Mar. 31, 2020
Schedule of Equity Method Investments [Line Items]
Non-cash impairment charge				$ 0	$ 76,800
October 2016 Investment | Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Percentage of equity interest held	10.00%		10.00%
Equity investments			$ 10,000
Non-cash impairment charge		$ 5,300

Intangible Assets, net - Intang

Intangible Assets, net - Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Cost	$ 303,379	$ 298,472
Accumulated Amortization	(215,668)	(203,705)
Net	87,711	94,767
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Cost	36,500	36,500
Accumulated Amortization	(5,105)	(3,822)
Net	31,395	32,678
Software
Finite-Lived Intangible Assets [Line Items]
Cost	33,764	28,515
Accumulated Amortization	(13,155)	(11,483)
Net	20,609	17,032
Developed technology
Finite-Lived Intangible Assets [Line Items]
Cost	86,064	86,064
Accumulated Amortization	(73,507)	(70,270)
Net	12,557	15,794
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	87,600	87,600
Accumulated Amortization	(76,429)	(73,301)
Net	11,171	14,299
Intangibles-in-progress
Finite-Lived Intangible Assets [Line Items]
Cost	9,886	11,863
Accumulated Amortization	0	0
Net	9,886	11,863
Purchased content
Finite-Lived Intangible Assets [Line Items]
Cost	49,565	47,930
Accumulated Amortization	(47,472)	(44,829)
Net	$ 2,093	$ 3,101

Intangible Assets, net - Additi

Intangible Assets, net - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Indefinite-lived Intangible Assets [Line Items]
Amortization of website development costs and intangible assets included in technology and development	$ 12,900,000	$ 11,800,000
Non-cash impairment charge	0	76,800,000
Finite-lived intangible assets, net	87,711,000		$ 94,767,000
Trade names and trademarks
Indefinite-lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	$ 31,395,000		$ 32,678,000
Trade names and trademarks | Trulia
Indefinite-lived Intangible Assets [Line Items]
Non-cash impairment charge		71,500,000
Indefinite-lived intangible asset		108,000,000
Fair value of the intangible asset		$ 36,500,000
Useful life			10 years

Debt - Schedule of Carrying Val

Debt - Schedule of Carrying Value of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total debt	$ 2,259,380	$ 2,283,732
Convertible senior notes
Debt Instrument [Line Items]
Total convertible senior notes	1,597,205	1,613,523
Convertible senior notes | 2026 Notes
Debt Instrument [Line Items]
Total convertible senior notes	$ 352,077	347,566
Stated Interest Rate	1.375%
Convertible senior notes | 2.75% convertible senior notes due 2025
Debt Instrument [Line Items]
Total convertible senior notes	$ 421,770	414,888
Stated Interest Rate	2.75%
Convertible senior notes | 2024 Notes
Debt Instrument [Line Items]
Total convertible senior notes	$ 493,044	524,273
Stated Interest Rate	0.75%
Convertible senior notes | 2023 Notes
Debt Instrument [Line Items]
Total convertible senior notes	$ 330,314	326,796
Stated Interest Rate	1.50%
Mortgages segment
Debt Instrument [Line Items]
Warehouse line of credit	$ 263,339	309,043
Line of Credit | Homes segment
Debt Instrument [Line Items]
Short-term debt	398,836	361,166
Goldman Sachs Bank USA | Line of Credit | Homes segment
Debt Instrument [Line Items]
Short-term debt	190,176	145,825
Citibank, N.A. | Mortgages segment
Debt Instrument [Line Items]
Short-term debt	50,546	90,227
Citibank, N.A. | Line of Credit | Homes segment
Debt Instrument [Line Items]
Short-term debt	109,732	87,103
Credit Suisse AG, Cayman Islands | Mortgages segment
Debt Instrument [Line Items]
Short-term debt	132,001	149,913
Credit Suisse AG, Cayman Islands | Line of Credit | Homes segment
Debt Instrument [Line Items]
Short-term debt	98,928	128,238
Comerica Bank | Line of Credit | Mortgages segment
Debt Instrument [Line Items]
Warehouse line of credit	$ 80,792	$ 68,903

Debt - Schedule of Credit Facil

Debt - Schedule of Credit Facilities (Details) - Homes segment - Line of Credit	Mar. 31, 2021USD ($)
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 1,500,000,000
Goldman Sachs Bank USA | Final Maturity Date, April 20, 2022
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 500,000,000
Weighted-Average Interest Rate	3.15%
Citibank, N.A. | Final Maturity Date, November 30, 2021
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 500,000,000
Weighted-Average Interest Rate	2.86%
Credit Suisse AG, Cayman Islands | Final Maturity Date, December 31, 2022
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 500,000,000
Weighted-Average Interest Rate	2.86%

Debt - Narrative (Detail)

Debt - Narrative (Detail)	3 Months Ended
	Mar. 31, 2021USD ($)day	Mar. 19, 2021USD ($)	Feb. 04, 2021USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Assets	$ 8,255,902,000			$ 7,486,560,000
Inventory	472,397,000			491,293,000
Restricted cash	120,713,000			75,805,000
Accounts receivable, net of allowance for doubtful accounts of $3,460 and $3,427 at March 31, 2021 and December 31, 2020, respectively	82,461,000			69,940,000
Liabilities	2,745,864,000			2,744,744,000
Borrowings under credit facilities	662,175,000			670,209,000
Accrued expenses and other current liabilities	121,692,000			94,487,000
Variable Interest Entity, Primary Beneficiary
Debt Instrument [Line Items]
Assets	573,600,000			551,200,000
Inventory	471,900,000			491,300,000
Restricted cash	83,200,000			53,000,000
Accounts receivable, net of allowance for doubtful accounts of $3,460 and $3,427 at March 31, 2021 and December 31, 2020, respectively	16,400,000			3,900,000
Liabilities	411,600,000			372,500,000
Borrowings under credit facilities	398,800,000			361,200,000
Accrued expenses and other current liabilities	$ 9,900,000			10,800,000
Convertible Senior Notes due 2023, 2024, 2025 and 2026 | Convertible senior notes
Debt Instrument [Line Items]
Debt instrument, convertible threshold trading days | day	20
Debt instrument, threshold consecutive trading days | day	30
Debt instrument, convertible threshold percentage	130.00%
Line of Credit | Homes segment
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 1,500,000,000
Short-term debt	398,836,000			361,166,000
Line of Credit | Mortgages segment
Debt Instrument [Line Items]
Maximum borrowing capacity	500,000,000
Comerica Bank | Line of Credit | Mortgages segment
Debt Instrument [Line Items]
Maximum borrowing capacity	100,000,000		$ 100,000,000
Citibank, N.A. | Mortgages segment
Debt Instrument [Line Items]
Short-term debt	50,546,000			90,227,000
Citibank, N.A. | Line of Credit | Homes segment
Debt Instrument [Line Items]
Short-term debt	109,732,000			87,103,000
Citibank, N.A. | Line of Credit | Mortgages segment
Debt Instrument [Line Items]
Maximum borrowing capacity	100,000,000
Repurchase agreement, committed amount		$ 25,000,000
Credit Suisse and Citibank, N.A | Mortgages segment
Debt Instrument [Line Items]
Short-term debt	$ 189,900,000			$ 240,100,000

Debt - Schedule of Warehouse Li

Debt - Schedule of Warehouse Lines of Credit (Details) - Line of Credit - Mortgages segment - USD ($)	Mar. 31, 2021	Mar. 19, 2021	Feb. 04, 2021
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 500,000,000
Credit Suisse AG, Cayman Islands
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 300,000,000	$ 300,000,000
Weighted-Average Interest Rate	2.50%
Citibank, N.A.
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 100,000,000
Weighted-Average Interest Rate	1.86%
Comerica Bank
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 100,000,000		$ 100,000,000
Weighted-Average Interest Rate	3.01%

Debt - Schedule of Convertible

Debt - Schedule of Convertible Senior Notes (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Interest Expense	$ 39,555,000	$ 37,592,000
Convertible senior notes
Debt Instrument [Line Items]
Aggregate Principal Amount	2,059,007,000
Unamortized Debt Discount and Debt Issuance Costs	461,802,000		$ 498,227,000
Fair Value	5,115,146,000		5,333,849,000
Contractual Coupon Interest	8,240,000	6,735,000
Amortization of Debt Discount	24,119,000	21,293,000
Amortization of Debt Issuance Costs	1,152,000	1,254,000
Interest Expense	33,511,000	29,282,000
Convertible senior notes | 2026 Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 498,800,000
Stated Interest Rate	1.375%
Effective Interest Rate	8.10%
Unamortized Debt Discount and Debt Issuance Costs	$ 146,723,000		152,434,000
Fair Value	1,476,837,000		1,508,675,000
Contractual Coupon Interest	1,717,000	1,719,000
Amortization of Debt Discount	5,226,000	4,824,000
Amortization of Debt Issuance Costs	128,000	118,000
Interest Expense	7,071,000	6,661,000
Convertible senior notes | 2.75% convertible senior notes due 2025
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 565,000,000
Stated Interest Rate	2.75%
Effective Interest Rate	10.32%
Unamortized Debt Discount and Debt Issuance Costs	$ 143,230,000		150,112,000
Fair Value	1,172,674,000		1,168,855,000
Contractual Coupon Interest	3,884,000	0
Amortization of Debt Discount	6,533,000	0
Amortization of Debt Issuance Costs	349,000	0
Interest Expense	10,766,000	0
Convertible senior notes | 2024 Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 622,382,000
Stated Interest Rate	0.75%
Effective Interest Rate	7.69%
Unamortized Debt Discount and Debt Issuance Costs	$ 129,338,000		148,727,000
Fair Value	1,854,113,000		2,023,280,000
Contractual Coupon Interest	1,238,000	1,248,000
Amortization of Debt Discount	8,410,000	7,861,000
Amortization of Debt Issuance Costs	289,000	267,000
Interest Expense	9,937,000	9,376,000
Convertible senior notes | 2023 Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 372,825,000
Stated Interest Rate	1.50%
Effective Interest Rate	6.99%
Unamortized Debt Discount and Debt Issuance Costs	$ 42,511,000		46,954,000
Fair Value	611,522,000		$ 633,039,000
Contractual Coupon Interest	1,401,000	1,402,000
Amortization of Debt Discount	3,950,000	3,697,000
Amortization of Debt Issuance Costs	386,000	361,000
Interest Expense	5,737,000	5,460,000
Convertible senior notes | 2.0% convertible senior notes due 2021
Debt Instrument [Line Items]
Contractual Coupon Interest	0	2,300,000
Amortization of Debt Discount	0	4,911,000
Amortization of Debt Issuance Costs	0	508,000
Interest Expense	0	7,719,000
Convertible senior notes | 2.75% convertible senior notes due 2020
Debt Instrument [Line Items]
Contractual Coupon Interest	0	66,000
Amortization of Debt Discount	0	0
Amortization of Debt Issuance Costs	0	0
Interest Expense	$ 0	$ 66,000

Debt - Summary of Conversion an

Debt - Summary of Conversion and Redemption Options and Details Related to Capped Call Confirmations (Details) - Convertible senior notes	3 Months Ended
	Mar. 31, 2021$ / shares
2026 Notes
Debt Instrument [Line Items]
Debt instrument, conversion rate shares	0.0229830
Conversion Price per Share (usd per share)	$ 43.51
Initial cap price (usd per share)	$ 80.5750
Cap Price Premium	150.00%
2.75% convertible senior notes due 2025
Debt Instrument [Line Items]
Debt instrument, conversion rate shares	0.0148810
Conversion Price per Share (usd per share)	$ 67.20
2024 Notes
Debt Instrument [Line Items]
Debt instrument, conversion rate shares	0.0229830
Conversion Price per Share (usd per share)	$ 43.51
Initial cap price (usd per share)	$ 72.5175
Cap Price Premium	125.00%
2023 Notes
Debt Instrument [Line Items]
Debt instrument, conversion rate shares	0.0127592
Conversion Price per Share (usd per share)	$ 78.37
Initial cap price (usd per share)	$ 105.45
Cap Price Premium	85.00%
2.0% convertible senior notes due 2021
Debt Instrument [Line Items]
Initial cap price (usd per share)	$ 69.19
Cap Price Premium	85.00%

Debt - Summary of Convertible D

Debt - Summary of Convertible Debt (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Debt Instrument [Line Items]
Loss on extinguishment of debt	$ (1,403)	$ 0
Convertible senior notes
Debt Instrument [Line Items]
Aggregate principal amount converted	$ 52,743
Shares of Class C capital stock issued upon conversion (in shares)	1,202,720,000
Total fair value of consideration transferred	$ 159,772
Consideration allocated to liability component	42,991
Carrying value of the liability component, net of unamortized debt discount and debt issuance costs	41,588
Loss on extinguishment of debt	1,403
Consideration allocated to the equity component	116,781
2023 Notes | Convertible senior notes
Debt Instrument [Line Items]
Aggregate principal amount converted	$ 925
Shares of Class C capital stock issued upon conversion (in shares)	11,789,000
Total fair value of consideration transferred	$ 1,643
Consideration allocated to liability component	841
Carrying value of the liability component, net of unamortized debt discount and debt issuance costs	818
Loss on extinguishment of debt	23
Consideration allocated to the equity component	802
2024 Notes | Convertible senior notes
Debt Instrument [Line Items]
Aggregate principal amount converted	$ 50,618
Shares of Class C capital stock issued upon conversion (in shares)	1,163,352,000
Total fair value of consideration transferred	$ 153,925
Consideration allocated to liability component	41,267
Carrying value of the liability component, net of unamortized debt discount and debt issuance costs	39,927
Loss on extinguishment of debt	1,340
Consideration allocated to the equity component	112,658
2026 Notes | Convertible senior notes
Debt Instrument [Line Items]
Aggregate principal amount converted	$ 1,200
Shares of Class C capital stock issued upon conversion (in shares)	27,579,000
Total fair value of consideration transferred	$ 4,204
Consideration allocated to liability component	883
Carrying value of the liability component, net of unamortized debt discount and debt issuance costs	843
Loss on extinguishment of debt	40
Consideration allocated to the equity component	$ 3,321

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Schedule Of Income Tax [Line Items]
Income tax benefit	$ (2,890,000)	$ (9,228,000)
Non-cash impairment charge	$ 0	76,800,000
Trulia
Schedule Of Income Tax [Line Items]
Income tax benefit		(9,700,000)
Trulia | Trade names and trademarks
Schedule Of Income Tax [Line Items]
Non-cash impairment charge		$ 71,500,000
Federal
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards			$ 1,700,000,000
State
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards			$ 53,200,000

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail)	Feb. 17, 2021USD ($)	Mar. 31, 2021Voteshares	Dec. 31, 2020shares
Class of Stock [Line Items]
Preferred stock, issued (in shares) | shares		0	0
Preferred stock, outstanding (in shares) | shares		0	0
Class A Common Stock
Class of Stock [Line Items]
Common stock holders voting right | Vote		1
Conversion of common stock conversion ratio		1
Class B Common Stock
Class of Stock [Line Items]
Common stock holders voting right | Vote		10
Class C Capital Stock | Equity Distribution Agreement
Class of Stock [Line Items]
Sale of stock, maximum consideration on transaction | $	$ 1,000,000,000

Shareholders' Equity - Summary

Shareholders' Equity - Summary of Equity Distribution (Details) - Class C Capital Stock - Equity Distribution Agreement $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)$ / sharesshares
Class of Stock [Line Items]
Shares of Class C capital stock sold (in shares) | shares	3,163,502
Weighted-average issuance price per share (usd per share) | $ / shares	$ 174.0511
Gross proceeds	$ 550,611
Net proceeds from sale of stock	544,600
Payments for commissions	$ 6,100

Share-Based Awards - Summary of

Share-Based Awards - Summary of Option Award (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Number of Shares Subject to Existing Options
Beginning Balance (in shares)	20,051,051
Granted (in shares)	8,226,833
Exercised (in shares)	(1,602,896)
Forfeited or cancelled (in shares)	(373,388)
Ending Balance (in shares)	26,301,600	20,051,051
Vested and exercisable (in shares)	9,411,270
Weighted- Average Exercise Price Per Share
Beginning Balance (usd per share)	$ 42.68
Granted (usd per share)	133.88
Exercised (usd per share)	38.15
Forfeited or cancelled (usd per share)	47.58
Ending Balance (usd per share)	71.41	$ 42.68
Vested and exercisable (usd per share)	$ 39.23
Weighted- Average Remaining Contractual Life (Years)
Weighted-Average Remaining Contractual Life, Outstanding	7 years 11 months 26 days	7 years 2 months 19 days
Weighted-Average Remaining Contractual Life, Vested and exercisable	6 years 18 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding	$ 1,580,222	$ 1,751,105
Aggregate Intrinsic Value, Vested and exercisable	$ 851,494

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
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Weighted-average fair value of options granted (usd per share)	$ 59.74	$ 20.75
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	52.00%	45.00%
Risk-free interest rate	0.57%	0.87%
Weighted-average expected life	4 years 6 months	5 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	55.00%	48.00%
Risk-free interest rate	0.90%	0.93%
Weighted-average expected life	5 years 9 months	5 years 6 months

Share-Based Awards - Additional

Share-Based Awards - Additional Information (Details) $ in Millions	Mar. 31, 2021USD ($)
Option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized cost of unvested share-based compensation awards	$ 638
Unvested restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 411.1

Share-Based Awards - Summary _2

Share-Based Awards - Summary of Restricted Stock Units Activity (Detail) - Unvested restricted stock units	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Restricted Stock Units
Beginning balance (in shares) | shares	7,316,557
Granted (in shares) | shares	930,831
Vested (in shares) | shares	(813,471)
Forfeited (in shares) | shares	(162,972)
Ending balance (in shares) | shares	7,270,945
Weighted- Average Grant- Date Fair Value
Unvested outstanding, beginning balance (usd per share) | $ / shares	$ 48.14
Granted (usd per share) | $ / shares	138.13
Vested (usd per share) | $ / shares	44.96
Forfeited (usd per share) | $ / shares	48.73
Unvested outstanding, ending balance (usd per share) | $ / shares	$ 60.01

Share-Based Awards - Effects of

Share-Based Awards - Effects of Share Based Compensation in Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	$ 63,673	$ 43,795
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	2,386	1,173
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	9,887	6,993
Technology and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	26,393	18,917
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation	$ 25,007	$ 16,712

Net Income (Loss) Per Share - M

Net Income (Loss) Per Share - Maximum Number of Shares and Conversion Price (Details) - Convertible senior notes shares in Thousands	3 Months Ended
	Mar. 31, 2021$ / sharesshares
September 1, 2026
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion Spread (in shares) | shares	11,464
Conversion Price per Share (usd per share) | $ / shares	$ 43.51
May 15, 2025
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion Spread (in shares) | shares	8,408
Conversion Price per Share (usd per share) | $ / shares	$ 67.20
September 1, 2024
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion Spread (in shares) | shares	14,304
Conversion Price per Share (usd per share) | $ / shares	$ 43.51
July 1, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion Spread (in shares) | shares	4,757
Conversion Price per Share (usd per share) | $ / shares	$ 78.37

Net Income (Loss) Per Share - S

Net Income (Loss) Per Share - Schedule of Denominators Used in Basic and Diluted Per Share Calculations (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Denominator for basic calculation (in shares)	243,234	210,674
Denominator for dilutive calculation (in shares)	259,346	210,674
Option awards
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities, share-based payment arrangements (in shares)	12,437	0
Unvested restricted stock units
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities, share-based payment arrangements (in shares)	3,675	0

Net Income (Loss) Per Share - A

Net Income (Loss) Per Share - Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
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)	42,683	31,693
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)	2,546	23,663
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)	303	7,623
Class A Common Stock | Convertible notes maturing in 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)	0	407
Class C Capital Stock | Convertible notes maturing in 2023, 2024, 2025 and 2026
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	39,834	0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)

Mar. 10, 2021image

Jun. 20, 2017USD ($)

Feb. 09, 2017USD ($)

Mar. 31, 2021USD ($)

Mar. 15, 2021patent

Dec. 31, 2020USD ($)

Sep. 18, 2020petitionpatent

Jul. 21, 2020patent

Sep. 17, 2019patent

Feb. 28, 2018claim

Feb. 16, 2018claim

Feb. 05, 2018claim

Sep. 30, 2017claim

Other Commitments [Line Items]

Outstanding letters of credit

$ 16,900,000

Outstanding surety bonds

10,400,000

$ 10,100,000

Number of infringed images found | image

2,700

Number of patents infringed | patent

2

3

5

7

Number of petitions filed | petition

4

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

2

Homes under contract to purchase that have not closed

Other Commitments [Line Items]

Value of homes under contract that have not closed

$ 511,300,000

Employee Benefit Plan - Additio

Employee Benefit Plan - Additional Information (Detail) - Zillow Merger - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
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	$ 7.7	$ 6.4

Segment Information and Reven_3

Segment Information and Revenue - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2021Segment
Segment Reporting [Abstract]
Number of reportable segments	3
Number of operating segments	3

Segment Information and Reven_4

Segment Information and Revenue - Revenue Categories (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Revenue:
Total revenue		$ 1,218,440	$ 1,125,821
Costs and expenses:
Cost of revenue	[1]	687,030	761,672
Sales and marketing		193,593	204,648
Technology and development		148,856	134,918
General and administrative		100,551	92,285
Impairment costs		0	76,800
Acquisition-related costs		817	0
Total costs and expenses		1,130,847	1,270,323
Income (loss) from operations		87,593	(144,502)
Other income		2,439	9,593
Interest expense		(39,555)	(37,592)
Income (loss) before income taxes		49,074	(172,501)
Homes segment
Revenue:
Total revenue		704,152	769,873
Costs and expenses:
Cost of revenue	[1]	640,618	732,199
Sales and marketing		55,025	71,589
Technology and development		37,139	32,538
General and administrative		25,532	23,421
Impairment costs		0	0
Acquisition-related costs		0	0
Total costs and expenses		758,314	859,747
Income (loss) from operations		(54,162)	(89,874)
Other income		0	0
Interest expense		(4,312)	(8,084)
Income (loss) before income taxes		(58,474)	(97,958)
Homes segment | Zillow Offers
Revenue:
Total revenue		700,974	769,112
Homes segment | Premier Agent
Revenue:
Total revenue		0	0
Homes segment | Other
Revenue:
Total revenue		3,178	761
Homes segment | Mortgages
Revenue:
Total revenue		0	0
IMT
Revenue:
Total revenue		446,328	330,666
Costs and expenses:
Cost of revenue	[1]	28,016	24,318
Sales and marketing		113,298	120,173
Technology and development		101,893	95,028
General and administrative		58,729	58,754
Impairment costs		0	73,900
Acquisition-related costs		817	0
Total costs and expenses		302,753	372,173
Income (loss) from operations		143,575	(41,507)
Other income		0	0
Interest expense		0	0
Income (loss) before income taxes		143,575	(41,507)
IMT | Zillow Offers
Revenue:
Total revenue		0	0
IMT | Premier Agent
Revenue:
Total revenue		334,318	242,106
IMT | Other
Revenue:
Total revenue		112,010	88,560
IMT | Mortgages
Revenue:
Total revenue		0	0
Mortgages segment
Revenue:
Total revenue		67,960	25,282
Costs and expenses:
Cost of revenue	[1]	18,396	5,155
Sales and marketing		25,270	12,886
Technology and development		9,824	7,352
General and administrative		16,290	10,110
Impairment costs		0	2,900
Acquisition-related costs		0	0
Total costs and expenses		69,780	38,403
Income (loss) from operations		(1,820)	(13,121)
Other income		1,732	202
Interest expense		(1,732)	(226)
Income (loss) before income taxes		(1,820)	(13,145)
Mortgages segment | Zillow Offers
Revenue:
Total revenue		0	0
Mortgages segment | Premier Agent
Revenue:
Total revenue		0	0
Mortgages segment | Other
Revenue:
Total revenue		0	0
Mortgages segment | Mortgages
Revenue:
Total revenue		$ 67,960	$ 25,282
[1]	____________________

Segment Information and Reven_5

Segment Information and Revenue - Depreciation and Amortization Expense and Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization expense	$ 28,899	$ 29,026
Share-based compensation expense	63,673	43,795
Homes segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization expense	4,293	3,575
Share-based compensation expense	15,921	11,304
IMT
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization expense	22,799	23,777
Share-based compensation expense	41,392	29,547
Mortgages segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization expense	1,807	1,674
Share-based compensation expense	$ 6,360	$ 2,944

Segment Information and Reven_6

Segment Information and Revenue - Reconciliation of Segment Gross Profit and Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting, Revenue Reconciling Item [Line Items]
Total segment income (loss) before income taxes	$ 49,074	$ (172,501)
Corporate interest expense	(39,555)	(37,592)
Corporate other income	2,439	9,593
Loss on extinguishment of debt	(1,403)	0
Consolidated income (loss) before income taxes	49,074	(172,501)
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total segment income (loss) before income taxes	83,281	(152,610)
Consolidated income (loss) before income taxes	83,281	(152,610)
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Corporate interest expense	(33,511)	(29,282)
Corporate other income	$ 707	$ 9,391

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details) $ in Millions	1 Months Ended
	Feb. 28, 2021USD ($)
ShowingTime.com, Inc.
Subsequent Event [Line Items]
Payments to Acquire Businesses, Gross	$ 500