Zillow (Z) 10-Q 9 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 01, 2019
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	ZG
Entity Registrant Name	ZILLOW GROUP, INC.
Entity Central Index Key	0001617640
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		58,318,212
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		6,217,447
Class C Capital Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		140,633,463

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 736,507	$ 651,058
Short-term investments	780,963	903,867
Accounts receivable, net of allowance for doubtful accounts of $4,942 and $4,838 at March 31, 2019 and December 31, 2018, respectively	70,605	66,083
Inventory	325,154	162,829
Mortgage loans held for sale	29,469	35,409
Prepaid expenses and other current assets	69,292	61,067
Restricted cash	27,595	12,385
Total current assets	2,039,585	1,892,698
Contract cost assets	46,176	45,819
Property and equipment, net	142,146	135,172
Right of use assets	102,056
Goodwill	1,984,907	1,984,907
Intangible assets, net	207,933	215,904
Other assets	16,763	16,616
Total assets	4,539,566	4,291,116
Current liabilities:
Accounts payable	7,708	7,471
Accrued expenses and other current liabilities	63,212	63,101
Accrued compensation and benefits	30,300	31,388
Revolving credit facilities	246,028	116,700
Warehouse lines of credit	27,991	33,018
Deferred revenue	36,105	34,080
Deferred rent, current portion	0	1,740
Lease liabilities, current portion	19,561
Total current liabilities	430,905	287,498
Deferred rent, net of current portion	0	19,945
Lease liabilities, net of current portion	102,405
Long-term debt	707,860	699,020
Deferred tax liabilities and other long-term liabilities	15,264	17,474
Total liabilities	1,256,434	1,023,937
Commitments and contingencies (Note 17)
Shareholders’ equity:
Preferred stock, $0.0001 par value; 30,000,000 shares authorized; no shares issued and outstanding	0	0
Additional paid-in capital	4,022,218	3,939,842
Accumulated other comprehensive income (loss)	197	(905)
Accumulated deficit	(739,304)	(671,779)
Total shareholders’ equity	3,283,132	3,267,179
Total liabilities and shareholders’ equity	4,539,566	4,291,116
Class A Common Stock
Shareholders’ equity:
Common stock/capital stock	6	6
Class B Common Stock
Shareholders’ equity:
Common stock/capital stock	1	1
Class C Capital Stock
Shareholders’ equity:
Common stock/capital stock	$ 14	$ 14

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts	$ 4,942	$ 4,838
Preferred stock, par value (usd per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	30,000,000	30,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Class A Common Stock
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	1,245,000,000	1,245,000,000
Common stock, issued (in shares)	58,315,359	58,051,448
Common stock, outstanding (in shares)	58,315,359	58,051,448
Class B Common Stock
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	15,000,000	15,000,000
Common stock, issued (in shares)	6,217,447	6,217,447
Common stock, outstanding (in shares)	6,217,447	6,217,447
Class C Capital Stock
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	600,000,000	600,000,000
Common stock, issued (in shares)	140,597,526	139,635,370
Common stock, outstanding (in shares)	140,597,526	139,635,370

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Revenue:
Revenue		$ 454,104	$ 299,879
Cost of revenue (exclusive of amortization)
Cost of revenue		151,348	23,919
Sales and marketing		161,587	137,291
Technology and development		107,770	93,933
General and administrative		95,774	56,073
Acquisition-related costs		352	0
Integration costs		0	27
Total costs and expenses		516,831	311,243
Loss from operations		(62,727)	(11,364)
Other income		9,168	2,446
Interest expense		(16,466)	(7,073)
Loss before income taxes		(70,025)	(15,991)
Income tax benefit (expense)		2,500	(2,600)
Net loss		$ (67,525)	$ (18,591)
Net loss per share - basic and diluted (usd per share)		$ (0.33)	$ (0.10)
Weighted-average shares outstanding - basic and diluted (in shares)		204,514	191,464
Amortization of website development costs and intangible assets included in technology and development		$ 11,000	$ 13,000
Technology and Development
Cost of revenue (exclusive of amortization)
Amortization of website development costs and intangible assets included in technology and development		14,400	22,549
IMT
Revenue:
Revenue		298,272	280,856
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	24,251	22,594
Sales and marketing		126,654	128,747
Technology and development		87,969	85,917
General and administrative		70,850	50,187
Integration costs		0	27
Total costs and expenses		309,724	287,472
Loss from operations		(11,452)
Other income		0
Interest expense		0
Loss before income taxes		(11,452)	(6,616)
Homes
Revenue:
Revenue		128,472	0
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	122,419	86
Sales and marketing		20,862	290
Technology and development		12,281	2,236
General and administrative		14,357	1,778
Integration costs		0	0
Total costs and expenses		169,919	4,390
Loss from operations		(41,447)
Other income		0
Interest expense		(3,758)
Loss before income taxes		(45,205)	(4,390)
Mortgages
Revenue:
Revenue		27,360	19,023
Cost of revenue (exclusive of amortization)
Cost of revenue	[1]	4,678	1,239
Sales and marketing		14,071	8,254
Technology and development		7,520	5,780
General and administrative		10,567	4,108
Integration costs		352	0
Total costs and expenses		37,188	19,381
Loss from operations		(9,828)
Other income		313
Interest expense		(101)
Loss before income taxes		$ (9,616)	$ (358)
[1]	Amortization of website development costs and intangible assets included in technology and development of $14,400 and $22,549 for the three months ended March 31, 2019 and 2018, respectively.

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (67,525)	$ (18,591)
Other comprehensive income (loss):
Unrealized gains (losses) on investments	1,144	(332)
Currency translation adjustments	(42)	(22)
Total other comprehensive income (loss)	1,102	(354)
Comprehensive loss	$ (66,423)	$ (18,945)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Class A Common Stock, Class B Common Stock and Class C Capital Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2017	$ 2,660,823	$ 20	$ 3,254,146	$ (592,243)	$ (1,100)
Beginning Balance (in shares) at Dec. 31, 2017		190,115,148
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	52,906		52,906
Issuance of common and capital stock upon exercise of stock options (in shares)		2,414,214
Vesting of restricted stock units	0
Vesting of restricted stock units (in shares)		394,844
Shares and value of restricted stock units withheld for tax liability	(28)		(28)
Shares and value of restricted stock units withheld for tax liability (in shares)		(607)
Share-based compensation expense	32,863		32,863
Portion of conversion recorded in additional paid-in-capital in connection with partial conversion of convertible notes maturing in 2020	500		500
Portion of conversion recorded in additional paid-in-capital in connection with partial conversion of convertible notes maturing in 2020 (in shares)		20,727
Net loss	(18,591)			(18,591)
Other comprehensive income (loss)	(354)				(354)
Ending Balance at Mar. 31, 2018	2,768,441	$ 20	3,340,387	(570,512)	(1,454)
Ending Balance (in shares) at Mar. 31, 2018		192,944,326
Beginning Balance at Dec. 31, 2018	3,267,179	$ 21	3,939,842	(671,779)	(905)
Beginning Balance (in shares) at Dec. 31, 2018		203,904,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common and capital stock upon exercise of stock options	$ 13,564		13,564
Issuance of common and capital stock upon exercise of stock options (in shares)	729,788	729,788
Vesting of restricted stock units	$ 0
Vesting of restricted stock units (in shares)		496,347
Shares and value of restricted stock units withheld for tax liability	(2)		(2)
Shares and value of restricted stock units withheld for tax liability (in shares)		(68)
Share-based compensation expense	68,814		68,814
Net loss	(67,525)
Other comprehensive income (loss)	1,102
Ending Balance at Mar. 31, 2019	$ 3,283,132	$ 21	$ 4,022,218	$ (739,304)	$ 197
Ending Balance (in shares) at Mar. 31, 2019		205,130,332

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities
Net loss	$ (67,525)	$ (18,591)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	20,525	26,906
Share-based compensation expense	66,124	30,741
Amortization of right of use assets	4,440
Amortization of contract cost assets	8,746	9,296
Amortization of discount and issuance costs on convertible notes maturing in 2023 and 2021	8,840	4,708
Deferred income taxes	(2,500)	2,600
Loss on disposal of property and equipment	1,704	1,803
Bad debt expense	128	(267)
Deferred rent	0	(3,090)
Accretion of bond discount	(1,733)	(137)
Changes in operating assets and liabilities:
Accounts receivable	(4,650)	105
Inventory	(162,325)	0
Mortgage loans held for sale	5,940	0
Prepaid expenses and other assets	(8,537)	(19,923)
Lease liabilities	(7,010)
Contract cost assets	(9,103)	(11,440)
Accounts payable	(133)	1,672
Accrued expenses and other current liabilities	328	(6,747)
Accrued compensation and benefits	(1,088)	3,637
Deferred revenue	2,025	3,379
Other long-term liabilities	290	0
Net cash provided by (used in) operating activities	(145,514)	24,652
Investing activities
Proceeds from maturities of investments	302,187	61,386
Purchases of investments	(176,412)	(76,729)
Purchases of property and equipment	(14,202)	(15,791)
Purchases of intangible assets	(3,269)	(1,098)
Net cash provided by (used in) investing activities	108,304	(32,232)
Financing activities
Proceeds from borrowing on revolving credit facilities	129,328	0
Net repayments on warehouse lines of credit	(5,025)	0
Proceeds from exercise of stock options	13,564	52,906
Value of equity awards withheld for tax liability	2	(28)
Net cash provided by financing activities	137,869	52,878
Net increase in cash, cash equivalents and restricted cash during period	100,659	45,298
Cash, cash equivalents and restricted cash at beginning of period	663,443	352,095
Cash, cash equivalents and restricted cash at end of period	764,102	397,393
Supplemental disclosures of cash flow information
Cash paid for interest	4,956	0
Noncash transactions:
Capitalized share-based compensation	2,690	2,120
Write-off of fully depreciated property and equipment	6,269	7,379
Write-off of fully amortized intangible assets	$ 3,200	$ 10,687

Organization and Description of

Organization and Description of Business	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Organization and Description of Business	Organization and Description of Business Zillow Group, Inc. operates the largest portfolio of real estate and home-related brands on mobile and the web which focus on all stages of the home lifecycle: renting, buying, selling and financing. Zillow Group is committed to empowering consumers with unparalleled data, inspiration and knowledge around homes and connecting them with great real estate professionals. The Zillow Group portfolio of consumer brands includes Zillow, Trulia, Zillow Home Loans, StreetEasy, HotPads, Naked Apartments, RealEstate.com and Out East. In addition, Zillow Group provides a comprehensive suite of marketing software and technology solutions to help real estate professionals maximize business opportunities and connect with millions of consumers. Zillow Offers provides homeowners in certain metropolitan areas with the opportunity to receive offers to purchase their home from Zillow. When Zillow buys a home, it makes certain repairs and lists the home for resale on the open market. Zillow also provides consumers with the opportunity to receive mortgage financing through Zillow Home Loans, a licensed mortgage lender. Zillow Group operates a number of business brands for real estate, rental and mortgage professionals, including Mortech, dotloop, Bridge Interactive and New Home Feed. Zillow, Inc. was incorporated as a Washington corporation in December 2004, and we launched the initial version of our website, Zillow.com, in February 2006. Zillow Group, Inc. was incorporated as a Washington corporation in July 2014 in connection with our acquisition of Trulia, Inc. (“Trulia”). Upon the closing of the Trulia acquisition in February 2015, each of Zillow, Inc. and Trulia became wholly owned subsidiaries of Zillow Group. Certain Significant Risks and Uncertainties

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements include Zillow Group, Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and accompanying notes included in Zillow Group, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2018 , which was filed with the SEC on February 21, 2019. The condensed consolidated balance sheet as of December 31, 2018 , included herein, was derived from the audited financial statements of Zillow Group, Inc. as of that date. The unaudited condensed consolidated interim financial statements, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly our financial position as of March 31, 2019 , our results of operations, comprehensive loss and cash flows for the three month periods ended March 31, 2019 and 2018 . The results of the three month period ended March 31, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019 or for any interim period or for any other future year. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenue and expenses during the periods presented. On an ongoing basis, we evaluate our estimates, including those related to the net realizable value of inventory, amortization period and recoverability of contract cost assets, website and software development costs, recoverability of long-lived assets and intangible assets with definite lives, share-based compensation, income taxes, business combinations, and the recoverability of goodwill and indefinite-lived intangible assets, among others. To the extent there are material differences between these estimates, judgments, or assumptions and actual results, our financial statements will be affected. Recently Adopted Accounting Standards In February 2018, the Financial Accounting Standards Board (“FASB”) issued guidance on income tax accounting related to the Tax Cuts and Jobs Act (the “Tax Act”). This guidance permits a reclassification from accumulated other comprehensive income (loss) to accumulated deficit for the adjustment of deferred taxes due to the reduction of the historical corporate income tax rate to the newly enacted corporate income tax rate under the Tax Act. It also requires certain disclosures regarding these reclassifications. The guidance is effective for interim and annual reporting periods beginning after December 15, 2018, and early adoption is permitted. This guidance must be applied either on a prospective basis in the period of adoption or retrospectively to each period in which the effect of the change in the corporate income tax rate is recognized. We adopted this guidance on January 1, 2019. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows. In March 2017, the FASB issued guidance related to the premium amortization on purchased callable debt securities. This guidance shortens the amortization period for certain callable debt securities purchased at a premium by requiring that the premium be amortized to the earliest call date. This guidance is effective for interim and annual reporting periods beginning after December 15, 2018, and early adoption is permitted. This guidance must be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. We adopted this guidance on January 1, 2019. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows. In February 2016, the FASB issued guidance on leases. This guidance requires the recognition of a right of use asset and lease liability on the balance sheet for all leases. This guidance also requires more detailed disclosures to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. This guidance is effective for interim and annual reporting periods beginning after December 15, 2018. In July 2018, the FASB issued certain targeted improvements to the accounting and disclosure requirements for leases, including an additional optional transition method that allows entities to initially apply the new standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption without restating prior periods. When adopting the lease guidance, an entity may elect a practical expedient package, under which it need not reassess (a) whether any expired or existing contracts are or contain leases; (b) the lease classification for any expired or existing leases; and (c) initial direct costs for any existing leases. These three practical expedients must be elected as a package and must be consistently applied to all existing leases at the date of adoption. We adopted the new guidance on leases on January 1, 2019 using the optional transition method and elected to adopt the practical expedient package. Under this approach, we did not restate the prior financial statements presented. Based on our lease portfolio as of December 31, 2018, we recorded on our consolidated balance sheet right of use assets of $106.5 million as well as operating lease liabilities of $129.0 million , and we removed the existing deferred rent balance of $22.5 million . The adoption of the standard did not have a material impact to our condensed consolidated statements of operations. Recently Issued Accounting Standards Not Yet Adopted In August 2018, the FASB issued guidance related to a customer’s accounting for implementation costs incurred in hosting arrangements. The guidance aligns the requirements for capitalizing implementation costs incurred in cloud computing arrangements with the requirements for capitalizing costs to develop or obtain internal-use software. This guidance is effective for interim and annual reporting periods beginning after December 15, 2019, and early adoption is permitted. This guidance may be applied either retrospectively or prospectively. We expect to adopt this guidance on January 1, 2020. We have not yet determined the impact the adoption of this guidance will have on our financial position, results of operations or cash flows. In August 2018, the FASB issued guidance related to disclosure requirements for fair value measurements. This guidance removes, modifies and adds disclosures related to fair value measurements. This guidance is effective for interim and annual periods beginning after December 15, 2019, and early adoption is permitted. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim and annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. We expect to adopt this guidance on January 1, 2020. We have not yet determined the impact the adoption of this guidance will have on our financial statement disclosures.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Accounting standards define fair value as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The standards also establish a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Assets and liabilities valued based on observable market data for similar instruments, such as quoted prices for similar assets or liabilities. • Level 3—Unobservable inputs that are supported by little or no market activity; instruments valued based on the best available data, some of which is internally developed, and considers risk premiums that a market participant would require. We applied the following methods and assumptions in estimating our fair value measurements: Cash equivalents — The fair value measurement of money market funds is based on quoted market prices in active markets. The fair value measurement of corporate notes and bonds, commercial paper, U.S. government agency securities and certificates of deposit is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means. Short-term investments — The fair value measurement of our short-term investments is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means. Restricted cash — Restricted cash consists of cash received from the resale of homes through Zillow Offers which is used to repay amounts borrowed on our revolving credit facilities (see Note 13 ) and amounts held in escrow related to funding home purchases in our mortgage origination business. The carrying value of restricted cash approximates fair value due to the short period of time amounts borrowed on the revolving credit facilities are outstanding. Mortgage loans held for sale —The fair value of mortgage loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Interest rate lock commitments —The fair value of interest rate lock commitments (“IRLCs”) is calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Expired commitments are excluded from the fair value measurement. We generally only issue IRLCs for products that meet specific purchaser guidelines. Since not all IRLCs will become closed loans, we adjust our fair value measurements for the estimated amount of IRLCs that will not close. Forward contracts —The fair value of mandatory loan sales commitments and derivative instruments such as forward sales of mortgage-backed securities that are utilized as hedging instruments are calculated by reference to quoted prices for similar assets. The following tables present the balances of assets and liabilities measured at fair value on a recurring basis, by level within the fair value hierarchy, as of the dates presented (in thousands): March 31, 2019 Total Level 1 Level 2 Cash equivalents: Money market funds $ 578,037 $ 578,037 $ — Commercial paper 9,940 — 9,940 Short-term investments: U.S. government agency securities 531,006 — 531,006 Corporate notes and bonds 115,682 — 115,682 Commercial paper 82,755 — 82,755 Municipal securities 33,331 — 33,331 Foreign government securities 14,965 — 14,965 Certificates of deposit 3,224 — 3,224 Mortgage origination-related: Mortgage loans held for sale 29,469 — 29,469 Interest rate lock commitments 1,257 — 1,257 Forward contracts - other current assets 19 — 19 Forward contracts - other current liabilities (226 ) — (226 ) Total $ 1,399,459 $ 578,037 $ 821,422 December 31, 2018 Total Level 1 Level 2 Cash equivalents: Money market funds $ 541,575 $ 541,575 $ — Commercial paper 3,999 — 3,999 Short-term investments: U.S. government agency securities 646,496 — 646,496 Corporate notes and bonds 112,933 — 112,933 Commercial paper 85,506 — 85,506 Municipal securities 39,306 — 39,306 Foreign government securities 14,915 — 14,915 Certificates of deposit 4,711 — 4,711 Mortgage origination-related: Mortgage loans held for sale 35,409 — 35,409 Interest rate lock commitments 847 — 847 Forward contracts - other current liabilities (125 ) — (125 ) Total $ 1,485,572 $ 541,575 $ 943,997 At March 31, 2019 , the notional amounts of the hedging instruments related to our mortgage loans held for sale were $41.6 million and $49.7 million for our interest rate lock commitments and forward contracts, respectively. At December 31, 2018 , the notional amounts of the hedging instruments related to our mortgage loans held for sale were $26.7 million and $28.8 million for our interest rate lock commitments and forward contracts, respectively. We do not have the right to offset our forward contract derivative positions. See Note 13 for the carrying amount and estimated fair value of the Company’s Convertible Senior Notes due in 2023, Convertible Senior Notes due in 2021 and Trulia’s Convertible Senior Notes due in 2020. We did no t have any material Level 3 assets or liabilities as of March 31, 2019 or December 31, 2018

Cash and Cash Equivalents, Shor

Cash and Cash Equivalents, Short-term Investments and Restricted Cash	3 Months Ended
	Mar. 31, 2019
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents, Short-term Investments and Restricted Cash	Cash and Cash Equivalents, Short-term Investments and Restricted Cash The following tables present the amortized cost, gross unrealized gains and losses and estimated fair market value of our cash and cash equivalents, available-for-sale investments and restricted cash as of the dates presented (in thousands): March 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 148,530 $ — $ — $ 148,530 Cash equivalents: Money market funds 578,037 — — 578,037 Commercial paper 9,940 — — 9,940 Short-term investments: U.S. government agency securities 530,938 268 (200 ) 531,006 Corporate notes and bonds 115,648 65 (31 ) 115,682 Commercial paper 82,755 — — 82,755 Municipal securities 33,263 74 (6 ) 33,331 Foreign government securities 14,963 2 — 14,965 Certificates of deposit 3,224 — — 3,224 Restricted cash 27,595 — — 27,595 Total $ 1,544,893 $ 409 $ (237 ) $ 1,545,065 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 105,484 $ — $ — $ 105,484 Cash equivalents: Money market funds 541,575 — — 541,575 Commercial paper 3,999 — — 3,999 Short-term investments: U.S. government agency securities 647,266 51 (821 ) 646,496 Corporate notes and bonds 113,109 1 (177 ) 112,933 Commercial paper 85,506 — — 85,506 Municipal securities 39,316 23 (33 ) 39,306 Foreign government securities 14,929 — (14 ) 14,915 Certificates of deposit 4,711 1 (1 ) 4,711 Restricted cash 12,385 — — 12,385 Total $ 1,568,280 $ 76 $ (1,046 ) $ 1,567,310 The following table presents available-for-sale investments by contractual maturity date as of March 31, 2019 (in thousands): Amortized Cost Estimated Fair Market Value Due in one year or less $ 723,241 $ 723,207 Due after one year through two years 57,550 57,756 Total $ 780,791 $ 780,963

Accounts Receivable, net

Accounts Receivable, net	3 Months Ended
	Mar. 31, 2019
Receivables [Abstract]
Accounts Receivable, net	Accounts Receivable, net The opening balance of accounts receivable, net was $66.1 million as of January 1, 2019. The following table presents the changes in the allowance for doubtful accounts (in thousands): Balance as of January 1, 2019 $ 4,838 Bad debt expense 128 Less: write-offs, net of recoveries and other adjustments (24 ) Balance as of March 31, 2019 $ 4,942

Inventory

Inventory	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Inventory	Inventory The components of inventory, net of applicable lower of cost or net realizable value write-downs, were as follows (in thousands): March 31, December 31, Work-in-progress $ 76,283 $ 45,943 Finished goods 248,871 116,886 Inventory $ 325,154 $ 162,829

Contract Cost Assets

Contract Cost Assets	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Contract Cost Assets	Contract Cost Assets As of March 31, 2019 and December 31, 2018 , we had $46.2 million and $45.8 million , respectively, of contract cost assets. During the three months ended March 31, 2019 and 2018 , we recorded no impairment losses. During the three months ended March 31, 2019 and 2018 , we recorded $8.7 million and $9.3 million The following table presents the changes in deferred revenue for the periods presented (in thousands): Three Months Ended Balance as of January 1, 2019 $ 34,080 Deferral of revenue 242,852 Less: Revenue recognized (240,827 ) Balance as of March 31, 2019 $ 36,105 During the three months ended March 31, 2019 , we recognized as revenue a total of $30.7 million

Property and Equipment, net

Property and Equipment, net	3 Months Ended
	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment, net	Property and Equipment, net The following table presents the detail of property and equipment as of the dates presented (in thousands): March 31, December 31, Website development costs $ 149,558 $ 149,891 Computer equipment 22,675 22,477 Leasehold improvements 74,888 65,012 Construction-in-progress 26,027 29,037 Office equipment, furniture and fixtures 42,401 39,510 Property and equipment 315,549 305,927 Less: accumulated amortization and depreciation (173,403 ) (170,755 ) Property and equipment, net $ 142,146 $ 135,172 We recorded depreciation expense related to property and equipment (other than website development costs) of $6.0 million and $4.2 million , respectively, during the three months ended March 31, 2019 and 2018 . We capitalized $10.0 million and $8.6 million , respectively, in website development costs during the three months ended March 31, 2019 and 2018 . Amortization expense for website development costs included in technology and development expenses was $3.4 million and $9.5 million , respectively, during the three months ended March 31, 2019 and 2018

Equity Investment

Equity Investment	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment	Equity Investment In October 2016, we purchased a 10% equity interest in a privately held variable interest entity within the real estate industry for $10.0 million . The entity is financed through its business operations. We are not the primary beneficiary of the entity, as we do not direct the activities that most significantly impact the entity’s economic performance. Therefore, we do not consolidate the entity. Our maximum exposure to loss is $10.0 million , the carrying amount of the investment as of March 31, 2019 . There has been no impairment or upward or downward adjustments to our equity investment as of March 31, 2019

Intangible Assets, net

Intangible Assets, net	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets, net	Intangible Assets, net The following tables present the detail of intangible assets subject to amortization as of the dates presented (in thousands): March 31, 2019 Cost Accumulated Amortization Net Purchased content $ 42,224 $ (33,017 ) $ 9,207 Software 24,770 (15,339 ) 9,431 Customer relationships 103,600 (63,861 ) 39,739 Developed technology 109,080 (73,459 ) 35,621 Trade names and trademarks 4,400 (4,400 ) — Zillow Home Loans lender licenses 400 (67 ) 333 Intangibles-in-progress 5,602 — 5,602 Total $ 290,076 $ (190,143 ) $ 99,933 December 31, 2018 Cost Accumulated Amortization Net Purchased content $ 42,110 $ (30,477 ) $ 11,633 Software 24,296 (13,925 ) 10,371 Customer relationships 103,900 (60,733 ) 43,167 Developed technology 111,980 (72,788 ) 39,192 Trade names and trademarks 4,900 (4,683 ) 217 Zillow Home Loans lender licenses 400 (17 ) 383 Intangibles-in-progress 2,941 — 2,941 Total $ 290,527 $ (182,623 ) $ 107,904 Amortization expense recorded for intangible assets for the three months ended March 31, 2019 and 2018 was $11.0 million and $13.0 million , respectively. We have an indefinite-lived intangible asset that we recorded in connection with our February 2015 acquisition of Trulia for Trulia’s trade names and trademarks that is not subject to amortization. The carrying value of the Trulia trade names and trademarks intangible asset was $108.0 million as of March 31, 2019 and December 31, 2018 .

Deferred Revenue

Deferred Revenue	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Deferred Revenue	Contract Cost Assets As of March 31, 2019 and December 31, 2018 , we had $46.2 million and $45.8 million , respectively, of contract cost assets. During the three months ended March 31, 2019 and 2018 , we recorded no impairment losses. During the three months ended March 31, 2019 and 2018 , we recorded $8.7 million and $9.3 million The following table presents the changes in deferred revenue for the periods presented (in thousands): Three Months Ended Balance as of January 1, 2019 $ 34,080 Deferral of revenue 242,852 Less: Revenue recognized (240,827 ) Balance as of March 31, 2019 $ 36,105 During the three months ended March 31, 2019 , we recognized as revenue a total of $30.7 million

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases Our lease portfolio is primarily composed of operating leases for our office space. We have lease agreements that include lease components (e.g., fixed rent) and non-lease components (e.g., common area maintenance), which are accounted for as a single component, as we have elected the practical expedient to group lease and non-lease components. We also elected the practical expedient to keep leases with an initial term of 12 months or less off the balance sheet and recognize the associated lease payments in the condensed consolidated statements of operations on a straight-line basis over the lease term. Our leases have remaining lease terms ranging from less than one year to five years , some of which include options to extend the lease term for up to an additional ten years . For example, our largest leases, which include our corporate headquarters in Seattle, Washington and office space in San Francisco, California, include options to extend the existing leases for two periods of five years each. As our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the lease commencement date in determining the present value of the lease payments. For those leases that existed as of January 1, 2019, we used our incremental borrowing rate based on information available at that date. We apply a portfolio approach for determining the incremental borrowing rate based on the applicable lease terms and the current economic environment, and we utilize the assistance of third-party specialists to assist us in determining our yield curve. The components of our operating lease expense are as follows for the three months ended March 31, 2019 (in thousands): Operating lease cost $ 6,523 Variable lease cost 4,781 Total lease cost $ 11,304 Cash paid for amounts included in the measurement of lease liabilities for the three months ended March 31, 2019 was $9.1 million . The weighted average remaining term for our leases as of March 31, 2019 was 5 years . The weighted average discount rate for our leases as of March 31, 2019 was 5.9% . Maturities of our operating lease liabilities by fiscal year are as follows as of March 31, 2019 (in thousands): Remainder of 2019 $ 19,196 2020 28,550 2021 28,090 2022 24,565 2023 22,388 All future years 19,009 Total lease payments 141,798 Less: Imputed interest (19,832 ) Present value of lease liabilities $ 121,966 As of March 31, 2019, we have additional office space operating leases that have not yet commenced with total lease payments of $112.9 million . Our expectation is that these operating leases will commence during fiscal year 2019 with lease terms of five to eleven years . The following table presents our future minimum payments for all operating leases as of December 31, 2018, including future minimum payments for operating leases that had not yet commenced as of December 31, 2018 totaling $112.9 million (in thousands): 2019 $ 29,085 2020 38,060 2021 40,099 2022 37,721 2023 36,458 All future years 85,462 Total future minimum lease payments $ 266,885

Debt

Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt	Debt Revolving Credit Facilities To provide capital for Zillow Offers, we utilize revolving credit facilities that are classified as current liabilities in our condensed consolidated balance sheets. The following table summarizes our revolving credit facilities as of the periods presented (in thousands, except interest rates): Effective Date Maximum Borrowing Capacity Outstanding Borrowings at March 31, 2019 Outstanding Borrowings at December 31, 2018 Weighted Average Interest Rate July 31, 2018 $ 500,000 $ 167,279 $ 116,700 6.00 % January 31, 2019 500,000 78,749 — 5.99 % Total $ 1,000,000 $ 246,028 $ 116,700 On January 31, 2019, certain wholly owned subsidiaries of Zillow Group entered into a revolving credit agreement with Citibank, N.A., as the directing lender, and certain other parties thereto. The credit agreement provides for a maximum borrowing capacity of $500.0 million (the “Maximum Amount”) with a current borrowing capacity of $79.0 million as of March 31, 2019 , which amount may be increased up to the Maximum Amount subject to the satisfaction of certain conditions, through a non-recourse credit facility secured by a pledge of the equity of certain Zillow Group subsidiaries that purchase and sell select residential properties through Zillow Offers. In certain circumstances Zillow Group may be obligated to fund some or all of the payment obligations under the credit agreement. The credit agreement has an initial term of two years and may be extended for up to one additional year subject to agreement by the directing lender. Zillow Group formed certain special purpose entities to effectuate the transactions contemplated by the January 31, 2019 revolving credit facility. Each special purpose entity is a wholly owned subsidiary of Zillow Group and a separate legal entity, and neither the assets nor credit of any such entity are available to satisfy the debts and other obligations of any affiliate or other entity. The July 31, 2018 revolving credit facility had an initial term of one year which may be extended for up to two additional years, subject to agreement by the directing lender, and has a current borrowing capacity of $177.3 million as of March 31, 2019. Zillow Group formed certain special purpose entities to effectuate the transactions contemplated by the July 31, 2018 revolving credit facility. Each special purpose entity is a wholly owned subsidiary of Zillow Group and a separate legal entity, and neither the assets nor credit of any such entity are available to satisfy the debts and other obligations of any affiliate or other entity. The stated interest rate on our revolving credit facilities is one-month LIBOR plus an applicable margin as defined in the respective credit agreements. Our revolving credit facilities include customary representations and warranties, covenants (including financial covenants applicable to Zillow Group), and provisions regarding events of default. As of March 31, 2019 , Zillow Group was in compliance with all financial covenants and no event of default had occurred. Our revolving credit facilities also require that we establish, maintain, and in certain circumstances fund, certain specified reserve accounts. These reserve accounts include, but are not limited to, interest reserves, insurance, tax reserves, renovation cost reserves and special reserves. Amounts funded to these reserve accounts and the collection accounts have been classified within our consolidated balance sheets as restricted cash. For additional details related to our revolving credit facilities, see Note 14 in the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2018. Warehouse Lines of Credit To provide capital for Zillow Home Loans, we utilize warehouse lines of credit that are classified as current liabilities in our condensed consolidated balance sheets. The following table summarizes our warehouse lines of credit as of the periods presented (in thousands, except interest rates): Maturity Date Maximum Borrowing Capacity Outstanding Borrowings at March 31, 2019 Outstanding Borrowings at December 31, 2018 Weighted Average Interest Rate July 15, 2019 $ 50,000 $ 13,300 $ 14,125 5.00 % June 29, 2019 50,000 14,691 18,892 5.00 % Total $ 100,000 $ 27,991 $ 33,017 Borrowings on the lines of credit bear interest at the one-month LIBOR plus an applicable margin, as defined in the credit agreements governing the warehouse lines of credit. The lines of credit include customary representations and warranties, covenants and provisions regarding events of default. As of March 31, 2019, Zillow Group was in compliance with all financial covenants and no event of default had occurred. Convertible Senior Notes The following table summarizes our outstanding convertible senior notes as of the periods presented (in thousands, except interest rates): Maturity Date Aggregate Principal Amount Fair Value at March 31, 2019 Fair Value at December 31, 2018 Stated Interest Rate Effective Interest Rate July 1, 2023 $ 373,750 $ 341,850 $ 321,855 1.50 % 6.99 % December 1, 2021 460,000 470,911 446,200 2.00 % 7.44 % December 15, 2020 9,637 16,842 16,744 2.75 % N/A Total $ 843,387 $ 829,603 $ 784,799 The convertible notes are senior unsecured obligations and are classified as long-term debt in our condensed consolidated balance sheets. Interest on the convertible notes is paid semi-annually. As of March 31, 2019 and December 31, 2018 , respectively, the total unamortized debt discount and debt issuance costs for our outstanding senior convertible notes were $135.5 million and $144.4 million . The convertible senior notes maturing in 2023 and 2021 are not redeemable or convertible as of March 31, 2019. The convertible senior notes maturing in 2020 are convertible, at the option of the holder, and redeemable, at our option, as of March 31, 2019.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We are subject to federal and state income taxes in the United States and in Canada. As of March 31, 2019 and December 31, 2018 , we have provided a valuation allowance against our net deferred tax assets that we believe, based on the weight of available evidence, are not more likely than not to be realized. Therefore, no material current tax liability or expense has been recorded in the condensed consolidated financial statements. We have accumulated federal tax losses of approximately $1,081.7 million as of December 31, 2018 , which are available to reduce future taxable income. We have accumulated state tax losses of approximately $32.5 million (tax effected) as of December 31, 2018

Share-Based Awards

Share-Based Awards	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Awards	Share-Based Awards Option Awards The following table summarizes option award activity for the three months ended March 31, 2019 : Number of Shares Subject to Existing Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2019 27,310,110 $ 34.04 6.23 $ 97,941 Granted 6,155,283 39.97 Exercised (729,788 ) 18.59 Forfeited or cancelled (993,437 ) 42.01 Outstanding at March 31, 2019 31,742,168 35.30 6.76 122,262 Vested and exercisable at March 31, 2019 16,791,512 30.84 4.83 101,912 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 2019 2018 Expected volatility 46%-47% 43%-45% Expected dividend yield — — Risk-free interest rate 2.38%-2.53% 2.52%-2.65% Weighted-average expected life 4.75-5.25 years 4.50-5.00 years Weighted-average fair value of options granted $16.77 $20.88 As of March 31, 2019 , there was a total of $229.5 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, 2019 : Restricted Stock Units Weighted- Average Grant- Date Fair Value Unvested outstanding at January 1, 2019 5,266,324 $ 42.19 Granted 2,749,293 39.06 Vested (496,347 ) 37.94 Forfeited or cancelled (273,753 ) 40.44 Unvested outstanding at March 31, 2019 7,245,517 41.36 As of March 31, 2019 , there was $279.8 million of total unrecognized compensation cost related to unvested restricted stock units. Share-Based Compensation Expense The following table presents the effects of share-based compensation in our condensed consolidated statements of operations during the periods presented (in thousands): Three Months Ended 2019 2018 Cost of revenue $ 881 $ 955 Sales and marketing 5,650 5,162 Technology and development 15,508 11,542 General and administrative 44,085 13,082 Total $ 66,124 $ 30,741 On February 21, 2019, Zillow Group announced the appointment of Richard N. Barton as Zillow Group’s Chief Executive Officer, effective February 21, 2019. Mr. Barton succeeds Spencer Rascoff, who served as Zillow Group’s Chief Executive Officer since 2010 and who remains a member of Zillow Group’s board of directors. In connection with Mr. Rascoff’s resignation as Chief Executive Officer, Zillow Group entered into an Executive Departure Agreement and Release (the “Agreement”) with Mr. Rascoff. Pursuant to the Agreement, Mr. Rascoff remained a full-time employee of Zillow Group until March 22, 2019 (the “Departure Date”) in order to provide transition services until such date. Pursuant to the Agreement, Mr. Rascoff received, among other things, accelerated vesting of outstanding stock options held by Mr. Rascoff as of the Departure Date by an additional eighteen months from the Departure Date. Options not vested as of the Departure Date, taking into account the foregoing vesting acceleration, were terminated. Each of Mr. Rascoff’s vested stock options outstanding as of the Departure Date will remain exercisable until, except for any later date contemplated by the following proviso, the earlier of (x) the third anniversary of the Departure Date and (y) the latest day upon which the option would have expired by its original terms under any circumstances (the “Option Expiration Outside Date”); provided, however, that the options will remain exercisable for so long as Mr. Rascoff serves on Zillow Group’s board of directors (but not later than any applicable Option Expiration Outside Date), and if Mr. Rascoff ceases to serve on Zillow Group’s board of directors on or after the third anniversary of the Departure Date, each option will remain exercisable until the earlier of (i) ninety days from the final date of Mr. Rascoff’s service on Zillow Group’s board of directors and (ii) the applicable Option Expiration Outside Date. The change in the exercise period of the options as well as the vesting acceleration pursuant to the Agreement have been accounted for as equity modifications, and we recorded $26.4 million of share-based compensation expense associated with the modifications in the three months ended March 31, 2019. We measured the modification charge by calculating the incremental fair value of the modified award compared to the fair value of the original award immediately prior to the modification. The value of the modified awards as of the modification date was estimated using the Black-Scholes-Merton option-pricing model, assuming no dividends, expected volatility of 46% - 47% , a risk-free interest rate of 2.47% - 2.49%

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share For the periods presented, the following Class A common stock and Class C capital stock equivalents were excluded from the calculations of diluted net loss per share because their effect would have been antidilutive (in thousands): Three Months Ended 2019 2018 Weighted-average Class A common stock and Class C capital stock option awards outstanding 19,408 25,222 Weighted-average Class A common stock and Class C capital stock restricted stock units outstanding 5,860 4,346 Class A common stock issuable upon conversion of the convertible notes maturing in 2020 421 403 Class C capital stock issuable related to conversion spread on the convertible notes maturing in 2021 — 235 Total Class A common stock and Class C capital stock equivalents 25,689 30,206

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Commitments We have entered into various non-cancelable operating lease agreements for certain of our office space and equipment with original lease periods expiring between 2019 and 2024. For additional information regarding our lease agreements, see Note 12 . Purchase Commitments Purchase commitments primarily include various non-cancelable agreements to purchase content related to our mobile applications and websites as well as homes we are under contract to purchase through Zillow Offers but that have not closed as of the respective date. As of March 31, 2019 , the value of homes under contract that have not closed was $140.2 million . 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 $8.6 million and $8.9 million , respectively, as of March 31, 2019 and December 31, 2018 . Legal Proceedings We are involved in a number of legal proceedings concerning matters arising in connection with the conduct of our business activities, some of which are at preliminary stages and some of which seek an indeterminate amount of damages. We regularly evaluate the status of legal proceedings in which we are involved to assess whether a loss is probable or there is a reasonable possibility that a loss or additional loss may have been incurred to determine if accruals are appropriate. We further evaluate each legal proceeding to assess whether an estimate of possible loss or range of loss can be made if accruals are not appropriate. For certain cases described below, management is unable to provide a meaningful estimate of the possible loss or range of possible loss because, among other reasons, (i) the proceedings are in preliminary stages; (ii) specific damages have not been sought; (iii) damages sought are, in our view, unsupported and/or exaggerated; (iv) there is uncertainty as to the outcome of pending appeals or motions; (v) there are significant factual issues to be resolved; and/or (vi) there are novel legal issues or unsettled legal theories presented. For these cases, however, management does not believe, based on currently available information, that the outcomes of these proceedings will have a material effect on our financial position, results of operations or cash flow. In July 2015, VHT, Inc. (“VHT”) filed a complaint against us in the U.S. District Court for the Western District of Washington alleging copyright infringement of VHT’s images on the Zillow Digs site. In January 2016, VHT filed an amended complaint alleging copyright infringement of VHT’s images on the Zillow Digs site as well as the Zillow listing site. In December 2016, the court granted a motion for partial summary judgment that dismissed VHT’s claims with respect to the Zillow listing site. A federal jury trial began on January 23, 2017, and on February 9, 2017, the jury returned a verdict finding that the Company had infringed VHT’s copyrights in images displayed or saved to the Digs site. The jury awarded VHT $79,875 in actual damages and approximately $8.2 million in statutory damages. In March 2017, the Company filed motions in the district court seeking judgment for the Company on certain claims that are the subject of the verdict, and for a new trial on others. On June 20, 2017, the judge ruled and granted in part our motions, finding that VHT failed to present sufficient evidence to prove direct copyright infringement for a portion of the images, reducing the total damages to approximately $4.1 million . On October 26, 2017, the Company 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 oral hearing for the appeal took place on August 28, 2018. On March 15, 2019, 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. We have recorded an estimated liability for immaterial amounts related to this matter as of March 31, 2019 and December 31, 2018. We do not believe there is a reasonable possibility that a material loss in excess of amounts accrued may be incurred. In August and September 2017, two purported class action lawsuits were filed against us and certain of our executive officers, alleging, among other things, violations of federal securities laws on behalf of a class of those who purchased our common stock between February 12, 2016 and August 8, 2017. One of those purported class actions, captioned Vargosko v. Zillow Group, Inc. et al, was brought in the U.S. District Court for the Central District of California. The other purported class action lawsuit, captioned Shotwell v. Zillow Group, Inc. et al, was brought in the U.S. District Court for the Western District of Washington. The complaints allege, among other things, that during the period between February 12, 2016 and August 8, 2017, we issued materially false and misleading statements regarding our business practices. The complaints seek to recover, among other things, alleged damages sustained by the purported class members as a result of the alleged misconduct. In November 2017, an amended complaint was filed against us and certain of our executive officers in the Shotwell v. Zillow Group class action lawsuit, extending the beginning of the class period to November 17, 2014. In January 2018, the Vargosko v. Zillow Group purported class action lawsuit was transferred to the U.S. District Court for the Western District of Washington and consolidated with the Shotwell v. Zillow Group purported class action lawsuit. In February 2018, the plaintiffs filed a consolidated amended complaint, and in April 2018, we filed our motion to dismiss the consolidated amended complaint. In May 2018, the plaintiffs filed their opposition to our motion to dismiss the consolidated amended complaint. In June 2018, we filed our reply in support of our motion to dismiss the consolidated amended complaint. In October 2018, our motion to dismiss was granted without prejudice, and the plaintiffs were given 45 days file a second consolidated amended complaint and attempt to cure the defects in their consolidated amended complaint. In November 2018, the plaintiffs filed a second consolidated amended complaint, which we moved to dismiss in December 2018. In January 2019, the plaintiffs filed their opposition to our motion to dismiss the second consolidated amended complaint. In February 2019, we filed our reply in support of our motion to dismiss the second consolidated amended complaint. 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. We have denied the allegations of wrongdoing and intend to vigorously defend the claims in this lawsuit. We have not recorded an accrual related to this lawsuit as of March 31, 2019 and December 31, 2018 , as we do not believe a loss is probable. In October and November 2017 and January and February 2018, four shareholder derivative lawsuits were filed in the U.S. District Court for the Western District of Washington and the Superior Court of the State of Washington, 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. All four of the shareholder derivative lawsuits have been stayed until after final resolution of pleading motions and related appeals, if any, in the consolidated securities class action lawsuit discussed above. The defendants intend to deny the allegations of wrongdoing and vigorously defend the claims in these lawsuits. We have not recorded an accrual related to these lawsuits as of March 31, 2019 and December 31, 2018 , as we do not believe a loss is probable. 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

Self-Insurance

Self-Insurance	3 Months Ended
	Mar. 31, 2019
Insurance [Abstract]
Self-Insurance	Self-Insurance We are self-insured for medical benefits and dental benefits for all qualifying Zillow Group employees. The medical plan carries a stop-loss policy which will protect when cumulative medical claims exceed 125% of expected claims for the plan year with a limit of $1.0 million and from individual claims during the plan year exceeding $500,000 . We record estimates of the total costs of claims incurred based on an analysis of historical data and independent estimates. Our liability for self-insured claims is included within accrued compensation and benefits in our condensed consolidated balance sheets and was $4.1 million and $ 3.9 million , respectively, as of March 31, 2019 and December 31, 2018

Employee Benefit Plan

Employee Benefit Plan	3 Months Ended
	Mar. 31, 2019
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit Plan We have a defined contribution 401(k) retirement plan covering Zillow Group employees who have met certain eligibility requirements (the “Zillow Group 401(k) Plan”). Eligible employees may contribute pretax compensation up to a maximum amount allowable under the Internal Revenue Service limitations. Employee contributions and earnings thereon vest immediately. We currently match up to 4% of employee contributions under the Zillow Group 401(k) Plan. The total expense related to the Zillow Group 401(k) Plan for the three months ended March 31, 2019 and 2018 was $4.9 million and $3.8 million

Segment Information and Revenue

Segment Information and Revenue	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Segment Information and Revenue	Segment Information and Revenue Beginning January 1, 2019, we have three operating and reportable segments, which have been identified based on the way in which our chief operating decision-maker manages our business, makes operating decisions and evaluates operating performance. The chief executive officer acts as the chief operating decision-maker and reviews financial and operational information for the Internet, Media & Technology (“IMT”), Homes and Mortgages segments. The IMT segment includes the financial results for the Premier Agent, Rentals and new construction marketplaces, dotloop, and display, as well as revenue from the sale of various other marketing and business products and services to real estate professionals. The Homes segment includes the financial results from Zillow Group’s buying and selling of homes directly. The Mortgages segment includes financial results for advertising sold to mortgage lenders and other mortgage professionals, mortgage originations through Zillow Home Loans and the sale of mortgages on the secondary market, as well as Mortech mortgage software solutions. Revenue and costs are directly attributed to our segments when possible. However, due to the integrated structure of our business, certain costs incurred by one segment may benefit the other segments. These costs primarily include headcount-related expenses and facilities costs and are allocated to each segment based on the estimated benefit each segment receives from such expenditures. The chief executive officer reviews information about our revenue categories as well as statement of operations data inclusive of loss before income taxes by segment. This information is included in the following tables for the periods presented (in thousands): Three Months Ended March 31, 2019 IMT Homes Mortgages Revenue: Premier Agent $ 217,735 $ — $ — Rentals 37,838 — — Other 42,699 — — Homes — 128,472 — Mortgages — — 27,360 Total revenue 298,272 128,472 27,360 Costs and expenses: Cost of revenue 24,251 122,419 4,678 Sales and marketing 126,654 20,862 14,071 Technology and development 87,969 12,281 7,520 General and administrative 70,850 14,357 10,567 Integration costs — — 352 Total costs and expenses 309,724 169,919 37,188 Loss from operations (11,452 ) (41,447 ) (9,828 ) Segment other income — — 313 Segment interest expense — (3,758 ) (101 ) Loss before income taxes (1) $ (11,452 ) $ (45,205 ) $ (9,616 ) Three Months Ended March 31, 2018 IMT Homes Mortgages Revenue: Premier Agent $ 213,732 $ — $ — Rentals 29,063 — — Other 38,061 — — Homes — — — Mortgages — — 19,023 Total revenue 280,856 — 19,023 Costs and expenses: Cost of revenue 22,594 86 1,239 Sales and marketing 128,747 290 8,254 Technology and development 85,917 2,236 5,780 General and administrative 50,187 1,778 4,108 Acquisition costs 27 — — Total costs and expenses 287,472 4,390 19,381 Loss from operations and loss before incomes taxes (1) $ (6,616 ) $ (4,390 ) $ (358 ) (1) The following table presents the reconciliation of total segment loss before income taxes to consolidated loss before income taxes for the periods presented (in thousands): Three Months Ended March 31, 2019 2018 Total segment loss before income taxes $ (66,273 ) $ (11,364 ) Corporate interest expense (12,607 ) (7,073 ) Corporate other income 8,855 2,446 Consolidated loss before income taxes $ (70,025 ) $ (15,991 )

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements include Zillow Group, Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and accompanying notes included in Zillow Group, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2018 , which was filed with the SEC on February 21, 2019. The condensed consolidated balance sheet as of December 31, 2018 , included herein, was derived from the audited financial statements of Zillow Group, Inc. as of that date. The unaudited condensed consolidated interim financial statements, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, necessary to present fairly our financial position as of March 31, 2019 , our results of operations, comprehensive loss and cash flows for the three month periods ended March 31, 2019 and 2018 . The results of the three month period ended March 31, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019
Use of Estimates	Use of EstimatesThe preparation of financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenue and expenses during the periods presented. On an ongoing basis, we evaluate our estimates, including those related to the net realizable value of inventory, amortization period and recoverability of contract cost assets, website and software development costs, recoverability of long-lived assets and intangible assets with definite lives, share-based compensation, income taxes, business combinations, and the recoverability of goodwill and indefinite-lived intangible assets, among others. To the extent there are material differences between these estimates, judgments, or assumptions and actual results, our financial statements will be affected.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards In February 2018, the Financial Accounting Standards Board (“FASB”) issued guidance on income tax accounting related to the Tax Cuts and Jobs Act (the “Tax Act”). This guidance permits a reclassification from accumulated other comprehensive income (loss) to accumulated deficit for the adjustment of deferred taxes due to the reduction of the historical corporate income tax rate to the newly enacted corporate income tax rate under the Tax Act. It also requires certain disclosures regarding these reclassifications. The guidance is effective for interim and annual reporting periods beginning after December 15, 2018, and early adoption is permitted. This guidance must be applied either on a prospective basis in the period of adoption or retrospectively to each period in which the effect of the change in the corporate income tax rate is recognized. We adopted this guidance on January 1, 2019. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows. In March 2017, the FASB issued guidance related to the premium amortization on purchased callable debt securities. This guidance shortens the amortization period for certain callable debt securities purchased at a premium by requiring that the premium be amortized to the earliest call date. This guidance is effective for interim and annual reporting periods beginning after December 15, 2018, and early adoption is permitted. This guidance must be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. We adopted this guidance on January 1, 2019. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows. In February 2016, the FASB issued guidance on leases. This guidance requires the recognition of a right of use asset and lease liability on the balance sheet for all leases. This guidance also requires more detailed disclosures to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. This guidance is effective for interim and annual reporting periods beginning after December 15, 2018. In July 2018, the FASB issued certain targeted improvements to the accounting and disclosure requirements for leases, including an additional optional transition method that allows entities to initially apply the new standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption without restating prior periods. When adopting the lease guidance, an entity may elect a practical expedient package, under which it need not reassess (a) whether any expired or existing contracts are or contain leases; (b) the lease classification for any expired or existing leases; and (c) initial direct costs for any existing leases. These three practical expedients must be elected as a package and must be consistently applied to all existing leases at the date of adoption. We adopted the new guidance on leases on January 1, 2019 using the optional transition method and elected to adopt the practical expedient package. Under this approach, we did not restate the prior financial statements presented. Based on our lease portfolio as of December 31, 2018, we recorded on our consolidated balance sheet right of use assets of $106.5 million as well as operating lease liabilities of $129.0 million , and we removed the existing deferred rent balance of $22.5 million . The adoption of the standard did not have a material impact to our condensed consolidated statements of operations. Recently Issued Accounting Standards Not Yet Adopted In August 2018, the FASB issued guidance related to a customer’s accounting for implementation costs incurred in hosting arrangements. The guidance aligns the requirements for capitalizing implementation costs incurred in cloud computing arrangements with the requirements for capitalizing costs to develop or obtain internal-use software. This guidance is effective for interim and annual reporting periods beginning after December 15, 2019, and early adoption is permitted. This guidance may be applied either retrospectively or prospectively. We expect to adopt this guidance on January 1, 2020. We have not yet determined the impact the adoption of this guidance will have on our financial position, results of operations or cash flows. In August 2018, the FASB issued guidance related to disclosure requirements for fair value measurements. This guidance removes, modifies and adds disclosures related to fair value measurements. This guidance is effective for interim and annual periods beginning after December 15, 2019, and early adoption is permitted. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim and annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. We expect to adopt this guidance on January 1, 2020. We have not yet determined the impact the adoption of this guidance will have on our financial statement disclosures.
Fair Value Measurements	Accounting standards define fair value as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The standards also establish a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Assets and liabilities valued based on observable market data for similar instruments, such as quoted prices for similar assets or liabilities. • Level 3—Unobservable inputs that are supported by little or no market activity; instruments valued based on the best available data, some of which is internally developed, and considers risk premiums that a market participant would require. We applied the following methods and assumptions in estimating our fair value measurements: Cash equivalents — The fair value measurement of money market funds is based on quoted market prices in active markets. The fair value measurement of corporate notes and bonds, commercial paper, U.S. government agency securities and certificates of deposit is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means. Short-term investments — The fair value measurement of our short-term investments is based on observable market-based inputs or inputs that are derived principally from or corroborated by observable market data by correlation or other means. Restricted cash — Restricted cash consists of cash received from the resale of homes through Zillow Offers which is used to repay amounts borrowed on our revolving credit facilities (see Note 13 ) and amounts held in escrow related to funding home purchases in our mortgage origination business. The carrying value of restricted cash approximates fair value due to the short period of time amounts borrowed on the revolving credit facilities are outstanding. Mortgage loans held for sale —The fair value of mortgage loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Interest rate lock commitments —The fair value of interest rate lock commitments (“IRLCs”) is calculated by reference to quoted prices in secondary markets for commitments to sell mortgage loans with similar characteristics. Expired commitments are excluded from the fair value measurement. We generally only issue IRLCs for products that meet specific purchaser guidelines. Since not all IRLCs will become closed loans, we adjust our fair value measurements for the estimated amount of IRLCs that will not close. Forward contracts
Segment Reporting	Beginning January 1, 2019, we have three operating and reportable segments, which have been identified based on the way in which our chief operating decision-maker manages our business, makes operating decisions and evaluates operating performance. The chief executive officer acts as the chief operating decision-maker and reviews financial and operational information for the Internet, Media & Technology (“IMT”), Homes and Mortgages segments. The IMT segment includes the financial results for the Premier Agent, Rentals and new construction marketplaces, dotloop, and display, as well as revenue from the sale of various other marketing and business products and services to real estate professionals. The Homes segment includes the financial results from Zillow Group’s buying and selling of homes directly. The Mortgages segment includes financial results for advertising sold to mortgage lenders and other mortgage professionals, mortgage originations through Zillow Home Loans and the sale of mortgages on the secondary market, as well as Mortech mortgage software solutions. Revenue and costs are directly attributed to our segments when possible. However, due to the integrated structure of our business, certain costs incurred by one segment may benefit the other segments. These costs primarily include headcount-related expenses and facilities costs and 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, 2019
Fair Value Disclosures [Abstract]
Summary of Balances of Cash Equivalents and Investments	The following tables present the balances of assets and liabilities measured at fair value on a recurring basis, by level within the fair value hierarchy, as of the dates presented (in thousands): March 31, 2019 Total Level 1 Level 2 Cash equivalents: Money market funds $ 578,037 $ 578,037 $ — Commercial paper 9,940 — 9,940 Short-term investments: U.S. government agency securities 531,006 — 531,006 Corporate notes and bonds 115,682 — 115,682 Commercial paper 82,755 — 82,755 Municipal securities 33,331 — 33,331 Foreign government securities 14,965 — 14,965 Certificates of deposit 3,224 — 3,224 Mortgage origination-related: Mortgage loans held for sale 29,469 — 29,469 Interest rate lock commitments 1,257 — 1,257 Forward contracts - other current assets 19 — 19 Forward contracts - other current liabilities (226 ) — (226 ) Total $ 1,399,459 $ 578,037 $ 821,422 December 31, 2018 Total Level 1 Level 2 Cash equivalents: Money market funds $ 541,575 $ 541,575 $ — Commercial paper 3,999 — 3,999 Short-term investments: U.S. government agency securities 646,496 — 646,496 Corporate notes and bonds 112,933 — 112,933 Commercial paper 85,506 — 85,506 Municipal securities 39,306 — 39,306 Foreign government securities 14,915 — 14,915 Certificates of deposit 4,711 — 4,711 Mortgage origination-related: Mortgage loans held for sale 35,409 — 35,409 Interest rate lock commitments 847 — 847 Forward contracts - other current liabilities (125 ) — (125 ) Total $ 1,485,572 $ 541,575 $ 943,997

Cash and Cash Equivalents, Sh_2

Cash and Cash Equivalents, Short-term Investments and Restricted Cash (Tables)	3 Months Ended
	Mar. 31, 2019
Cash and Cash Equivalents [Abstract]
Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Market Value of Cash and Cash Equivalents and Available-for-Sale Investments	The following tables present the amortized cost, gross unrealized gains and losses and estimated fair market value of our cash and cash equivalents, available-for-sale investments and restricted cash as of the dates presented (in thousands): March 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 148,530 $ — $ — $ 148,530 Cash equivalents: Money market funds 578,037 — — 578,037 Commercial paper 9,940 — — 9,940 Short-term investments: U.S. government agency securities 530,938 268 (200 ) 531,006 Corporate notes and bonds 115,648 65 (31 ) 115,682 Commercial paper 82,755 — — 82,755 Municipal securities 33,263 74 (6 ) 33,331 Foreign government securities 14,963 2 — 14,965 Certificates of deposit 3,224 — — 3,224 Restricted cash 27,595 — — 27,595 Total $ 1,544,893 $ 409 $ (237 ) $ 1,545,065 December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Market Value Cash $ 105,484 $ — $ — $ 105,484 Cash equivalents: Money market funds 541,575 — — 541,575 Commercial paper 3,999 — — 3,999 Short-term investments: U.S. government agency securities 647,266 51 (821 ) 646,496 Corporate notes and bonds 113,109 1 (177 ) 112,933 Commercial paper 85,506 — — 85,506 Municipal securities 39,316 23 (33 ) 39,306 Foreign government securities 14,929 — (14 ) 14,915 Certificates of deposit 4,711 1 (1 ) 4,711 Restricted cash 12,385 — — 12,385 Total $ 1,568,280 $ 76 $ (1,046 ) $ 1,567,310
Available-for-Sale Investments by Contractual Maturity	The following table presents available-for-sale investments by contractual maturity date as of March 31, 2019 (in thousands): Amortized Cost Estimated Fair Market Value Due in one year or less $ 723,241 $ 723,207 Due after one year through two years 57,550 57,756 Total $ 780,791 $ 780,963

Accounts Receivable, net (Table

Accounts Receivable, net (Tables)	3 Months Ended
	Mar. 31, 2019
Receivables [Abstract]
Schedule of Accounts Receivable, Net	The following table presents the changes in the allowance for doubtful accounts (in thousands): Balance as of January 1, 2019 $ 4,838 Bad debt expense 128 Less: write-offs, net of recoveries and other adjustments (24 ) Balance as of March 31, 2019 $ 4,942

Inventory (Tables)

Inventory (Tables)	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Components of Net Inventory	The components of inventory, net of applicable lower of cost or net realizable value write-downs, were as follows (in thousands): March 31, December 31, Work-in-progress $ 76,283 $ 45,943 Finished goods 248,871 116,886 Inventory $ 325,154 $ 162,829

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	3 Months Ended
	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Detail of Property and Equipment	The following table presents the detail of property and equipment as of the dates presented (in thousands): March 31, December 31, Website development costs $ 149,558 $ 149,891 Computer equipment 22,675 22,477 Leasehold improvements 74,888 65,012 Construction-in-progress 26,027 29,037 Office equipment, furniture and fixtures 42,401 39,510 Property and equipment 315,549 305,927 Less: accumulated amortization and depreciation (173,403 ) (170,755 ) Property and equipment, net $ 142,146 $ 135,172

Intangible Assets, net (Tables)

Intangible Assets, net (Tables)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	The following tables present the detail of intangible assets subject to amortization as of the dates presented (in thousands): March 31, 2019 Cost Accumulated Amortization Net Purchased content $ 42,224 $ (33,017 ) $ 9,207 Software 24,770 (15,339 ) 9,431 Customer relationships 103,600 (63,861 ) 39,739 Developed technology 109,080 (73,459 ) 35,621 Trade names and trademarks 4,400 (4,400 ) — Zillow Home Loans lender licenses 400 (67 ) 333 Intangibles-in-progress 5,602 — 5,602 Total $ 290,076 $ (190,143 ) $ 99,933 December 31, 2018 Cost Accumulated Amortization Net Purchased content $ 42,110 $ (30,477 ) $ 11,633 Software 24,296 (13,925 ) 10,371 Customer relationships 103,900 (60,733 ) 43,167 Developed technology 111,980 (72,788 ) 39,192 Trade names and trademarks 4,900 (4,683 ) 217 Zillow Home Loans lender licenses 400 (17 ) 383 Intangibles-in-progress 2,941 — 2,941 Total $ 290,527 $ (182,623 ) $ 107,904

Deferred Revenue (Tables)

Deferred Revenue (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Schedule of Change in Deferred Revenue	The following table presents the changes in deferred revenue for the periods presented (in thousands): Three Months Ended Balance as of January 1, 2019 $ 34,080 Deferral of revenue 242,852 Less: Revenue recognized (240,827 ) Balance as of March 31, 2019 $ 36,105

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Components of Lease Expense	The components of our operating lease expense are as follows for the three months ended March 31, 2019 (in thousands): Operating lease cost $ 6,523 Variable lease cost 4,781 Total lease cost $ 11,304
Schedule of Maturities for Operating Lease Liabilities	Maturities of our operating lease liabilities by fiscal year are as follows as of March 31, 2019 (in thousands): Remainder of 2019 $ 19,196 2020 28,550 2021 28,090 2022 24,565 2023 22,388 All future years 19,009 Total lease payments 141,798 Less: Imputed interest (19,832 ) Present value of lease liabilities $ 121,966
Schedule of Future Minimum Payments for Operating Leases	The following table presents our future minimum payments for all operating leases as of December 31, 2018, including future minimum payments for operating leases that had not yet commenced as of December 31, 2018 totaling $112.9 million (in thousands): 2019 $ 29,085 2020 38,060 2021 40,099 2022 37,721 2023 36,458 All future years 85,462 Total future minimum lease payments $ 266,885

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of Revolving Credit Facilities and Lines of Credit	The following table summarizes our warehouse lines of credit as of the periods presented (in thousands, except interest rates): Maturity Date Maximum Borrowing Capacity Outstanding Borrowings at March 31, 2019 Outstanding Borrowings at December 31, 2018 Weighted Average Interest Rate July 15, 2019 $ 50,000 $ 13,300 $ 14,125 5.00 % June 29, 2019 50,000 14,691 18,892 5.00 % Total $ 100,000 $ 27,991 $ 33,017 Effective Date Maximum Borrowing Capacity Outstanding Borrowings at March 31, 2019 Outstanding Borrowings at December 31, 2018 Weighted Average Interest Rate July 31, 2018 $ 500,000 $ 167,279 $ 116,700 6.00 % January 31, 2019 500,000 78,749 — 5.99 % Total $ 1,000,000 $ 246,028 $ 116,700
Schedule of Convertible Senior Notes	The following table summarizes our outstanding convertible senior notes as of the periods presented (in thousands, except interest rates): Maturity Date Aggregate Principal Amount Fair Value at March 31, 2019 Fair Value at December 31, 2018 Stated Interest Rate Effective Interest Rate July 1, 2023 $ 373,750 $ 341,850 $ 321,855 1.50 % 6.99 % December 1, 2021 460,000 470,911 446,200 2.00 % 7.44 % December 15, 2020 9,637 16,842 16,744 2.75 % N/A Total $ 843,387 $ 829,603 $ 784,799

Share-Based Awards (Tables)

Share-Based Awards (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Option Award Activity	The following table summarizes option award activity for the three months ended March 31, 2019 : Number of Shares Subject to Existing Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding at January 1, 2019 27,310,110 $ 34.04 6.23 $ 97,941 Granted 6,155,283 39.97 Exercised (729,788 ) 18.59 Forfeited or cancelled (993,437 ) 42.01 Outstanding at March 31, 2019 31,742,168 35.30 6.76 122,262 Vested and exercisable at March 31, 2019 16,791,512 30.84 4.83 101,912
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 2019 2018 Expected volatility 46%-47% 43%-45% Expected dividend yield — — Risk-free interest rate 2.38%-2.53% 2.52%-2.65% Weighted-average expected life 4.75-5.25 years 4.50-5.00 years Weighted-average fair value of options granted $16.77 $20.88
Summary of Restricted Stock Units Activity	The following table summarizes activity for restricted stock units for the three months ended March 31, 2019 : Restricted Stock Units Weighted- Average Grant- Date Fair Value Unvested outstanding at January 1, 2019 5,266,324 $ 42.19 Granted 2,749,293 39.06 Vested (496,347 ) 37.94 Forfeited or cancelled (273,753 ) 40.44 Unvested outstanding at March 31, 2019 7,245,517 41.36
Effects of Share Based Compensation in Consolidated Statements of Operations	The following table presents the effects of share-based compensation in our condensed consolidated statements of operations during the periods presented (in thousands): Three Months Ended 2019 2018 Cost of revenue $ 881 $ 955 Sales and marketing 5,650 5,162 Technology and development 15,508 11,542 General and administrative 44,085 13,082 Total $ 66,124 $ 30,741

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share	For the periods presented, the following Class A common stock and Class C capital stock equivalents were excluded from the calculations of diluted net loss per share because their effect would have been antidilutive (in thousands): Three Months Ended 2019 2018 Weighted-average Class A common stock and Class C capital stock option awards outstanding 19,408 25,222 Weighted-average Class A common stock and Class C capital stock restricted stock units outstanding 5,860 4,346 Class A common stock issuable upon conversion of the convertible notes maturing in 2020 421 403 Class C capital stock issuable related to conversion spread on the convertible notes maturing in 2021 — 235 Total Class A common stock and Class C capital stock equivalents 25,689 30,206

Segment Information and Reven_2

Segment Information and Revenue (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Revenue Categories	This information is included in the following tables for the periods presented (in thousands): Three Months Ended March 31, 2019 IMT Homes Mortgages Revenue: Premier Agent $ 217,735 $ — $ — Rentals 37,838 — — Other 42,699 — — Homes — 128,472 — Mortgages — — 27,360 Total revenue 298,272 128,472 27,360 Costs and expenses: Cost of revenue 24,251 122,419 4,678 Sales and marketing 126,654 20,862 14,071 Technology and development 87,969 12,281 7,520 General and administrative 70,850 14,357 10,567 Integration costs — — 352 Total costs and expenses 309,724 169,919 37,188 Loss from operations (11,452 ) (41,447 ) (9,828 ) Segment other income — — 313 Segment interest expense — (3,758 ) (101 ) Loss before income taxes (1) $ (11,452 ) $ (45,205 ) $ (9,616 ) Three Months Ended March 31, 2018 IMT Homes Mortgages Revenue: Premier Agent $ 213,732 $ — $ — Rentals 29,063 — — Other 38,061 — — Homes — — — Mortgages — — 19,023 Total revenue 280,856 — 19,023 Costs and expenses: Cost of revenue 22,594 86 1,239 Sales and marketing 128,747 290 8,254 Technology and development 85,917 2,236 5,780 General and administrative 50,187 1,778 4,108 Acquisition costs 27 — — Total costs and expenses 287,472 4,390 19,381 Loss from operations and loss before incomes taxes (1) $ (6,616 ) $ (4,390 ) $ (358 ) (1) The following table presents the reconciliation of total segment loss before income taxes to consolidated loss before income taxes for the periods presented (in thousands): Three Months Ended March 31, 2019 2018 Total segment loss before income taxes $ (66,273 ) $ (11,364 ) Corporate interest expense (12,607 ) (7,073 ) Corporate other income 8,855 2,446 Consolidated loss before income taxes $ (70,025 ) $ (15,991 )
Reconciliation of Total Segment Loss	The following table presents the reconciliation of total segment loss before income taxes to consolidated loss before income taxes for the periods presented (in thousands): Three Months Ended March 31, 2019 2018 Total segment loss before income taxes $ (66,273 ) $ (11,364 ) Corporate interest expense (12,607 ) (7,073 ) Corporate other income 8,855 2,446 Consolidated loss before income taxes $ (70,025 ) $ (15,991 )

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Right of use assets	$ 102,056
Operating lease liabilities	$ 121,966
Accounting Standards Update 2016-02
Property, Plant and Equipment [Line Items]
Right of use assets		$ 106,500
Operating lease liabilities		$ 129,000
Removal of deferred rent balance			$ 22,500

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Cash Equivalents and Investments (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 780,963
Mortgage loans held for sale	29,469	$ 35,409
Total	1,399,459	1,485,572
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	0	0
Total	578,037	541,575
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	29,469	35,409
Total	821,422	943,997
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	578,037	541,575
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	578,037	541,575
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	9,940	3,999
Short-term investments	82,755	85,506
Commercial paper | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term investments	0	0
Commercial paper | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	9,940	3,999
Short-term investments	82,755	85,506
U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	531,006	646,496
U.S. government agency securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
U.S. government agency securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	531,006	646,496
Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	115,682	112,933
Corporate notes and bonds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Corporate notes and bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	115,682	112,933
Municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	33,331	39,306
Municipal securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Municipal securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	33,331	39,306
Foreign government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	14,965	14,915
Foreign government securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Foreign government securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	14,965	14,915
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	3,224	4,711
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	3,224	4,711
Interest rate lock commitments | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,257	847
Interest rate lock commitments | Level 1 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Interest rate lock commitments | Level 2 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,257	847
Forward contracts | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	19	(125)
Derivative liability	(226)
Forward contracts | Level 1 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Derivative liability	0
Forward contracts | Level 2 | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	19	$ (125)
Derivative liability	$ (226)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value	$ 0	$ 0
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Interest rate lock commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	41,600,000	26,700,000
Forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	$ 49,700,000	$ 28,800,000

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, 2019	Dec. 31, 2018
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 736,507	$ 651,058
Short-term investments:
Amortized Cost	780,791
Gross Unrealized Gains	409	76
Gross Unrealized Losses	(237)
Estimated Fair Market Value	780,963
Restricted cash	27,595	12,385
Cash, cash equivalents, short-term investments, and restricted cash, amortized cost	1,544,893	1,568,280
Cash, cash equivalents, short-term investments, and restricted cash, gross unrealized losses		(1,046)
Cash, cash equivalents, short-term investments, and restricted cash, estimated fair market value	1,545,065	1,567,310
U.S. government agency securities
Short-term investments:
Amortized Cost	530,938	647,266
Gross Unrealized Gains	268	51
Gross Unrealized Losses	(200)	(821)
Estimated Fair Market Value	531,006	646,496
Corporate notes and bonds
Short-term investments:
Amortized Cost	115,648	113,109
Gross Unrealized Gains	65	1
Gross Unrealized Losses	(31)	(177)
Estimated Fair Market Value	115,682	112,933
Commercial paper
Short-term investments:
Amortized Cost	82,755	85,506
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	82,755	85,506
Municipal securities
Short-term investments:
Amortized Cost	33,263	39,316
Gross Unrealized Gains	74	23
Gross Unrealized Losses	(6)	(33)
Estimated Fair Market Value	33,331	39,306
Foreign government securities
Short-term investments:
Amortized Cost	14,963	14,929
Gross Unrealized Gains	2	0
Gross Unrealized Losses	0	(14)
Estimated Fair Market Value	14,965	14,915
Certificates of deposit
Short-term investments:
Amortized Cost	3,224	4,711
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	(1)
Estimated Fair Market Value	3,224	4,711
Cash
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	148,530	105,484
Money market funds
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	578,037	541,575
Commercial paper
Cash and Cash Equivalents, at Carrying Value [Abstract]
Cash and cash equivalents	$ 9,940	$ 3,999

Cash and Cash Equivalents, Sh_4

Cash and Cash Equivalents, Short-term Investments and Restricted Cash - Available-for-Sale Investments by Contractual Maturity (Detail) $ in Thousands	Mar. 31, 2019USD ($)
Cash and Cash Equivalents [Abstract]
Amortized Cost, Due in one year or less	$ 723,241
Amortized Cost, Due after one year through two years	57,550
Amortized Cost	780,791
Estimated Fair Market Value, Due in one year or less	723,207
Estimated Fair Market Value, Due after one year through two years	57,756
Total	$ 780,963

Accounts Receivable, net (Detai

Accounts Receivable, net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018
Receivables [Abstract]
Accounts receivable, net	$ 70,605		$ 66,100	$ 66,083
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	4,838
Bad debt expense	128	$ (267)
Less: write-offs, net of recoveries and other adjustments	(24)
Ending balance	$ 4,942

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Work-in-progress	$ 76,283	$ 45,943
Finished goods	248,871	116,886
Inventory	$ 325,154	$ 162,829

Contract Cost Assets (Details)

Contract Cost Assets (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract cost assets	$ 46,176,000		$ 45,819,000
Impairment of contract cost assets	0	$ 0
Amortization of contract cost assets	$ 8,746,000	$ 9,296,000

Property and Equipment, net - D

Property and Equipment, net - Detail of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment	$ 315,549	$ 305,927
Less: accumulated amortization and depreciation	(173,403)	(170,755)
Property and equipment, net	142,146	135,172
Website development costs
Property, Plant and Equipment [Line Items]
Property and equipment	149,558	149,891
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	22,675	22,477
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	74,888	65,012
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property and equipment	26,027	29,037
Office equipment, furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	$ 42,401	$ 39,510

Property and Equipment, net - A

Property and Equipment, net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Amortization and depreciation expense related to property and equipment other than website development costs	$ 6	$ 4.2
Capitalization of website development costs	10	8.6
Amortization of website development costs and intangible assets included in technology and development	11	13
Technology and development | Software Development
Property, Plant and Equipment [Line Items]
Amortization of website development costs and intangible assets included in technology and development	$ 3.4	$ 9.5

Equity Investment - Additional

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

Intangible Assets, net - Intang

Intangible Assets, net - Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Cost	$ 290,076	$ 290,527
Accumulated Amortization	(190,143)	(182,623)
Net	99,933	107,904
Purchased content
Finite-Lived Intangible Assets [Line Items]
Cost	42,224	42,110
Accumulated Amortization	(33,017)	(30,477)
Net	9,207	11,633
Software
Finite-Lived Intangible Assets [Line Items]
Cost	24,770	24,296
Accumulated Amortization	(15,339)	(13,925)
Net	9,431	10,371
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Cost	103,600	103,900
Accumulated Amortization	(63,861)	(60,733)
Net	39,739	43,167
Developed technology
Finite-Lived Intangible Assets [Line Items]
Cost	109,080	111,980
Accumulated Amortization	(73,459)	(72,788)
Net	35,621	39,192
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Cost	4,400	4,900
Accumulated Amortization	(4,400)	(4,683)
Net	0	217
Zillow Home Loans lender licenses
Finite-Lived Intangible Assets [Line Items]
Cost	400	400
Accumulated Amortization	(67)	(17)
Net	333	383
Intangibles-in-progress
Finite-Lived Intangible Assets [Line Items]
Cost	5,602	2,941
Accumulated Amortization	0	0
Net	$ 5,602	$ 2,941

Intangible Assets, net - Additi

Intangible Assets, net - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Indefinite-lived Intangible Assets [Line Items]
Amortization of website development costs and intangible assets included in technology and development	$ 11	$ 13
Trade names and trademarks | Trulia
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible asset	$ 108		$ 108

Deferred Revenue (Details)

Deferred Revenue (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Change in Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 34,080
Deferral of revenue	242,852
Less: Revenue recognized	(240,827)
Ending balance	36,105
Revenue recognized, recorded in deferred revenue as of prior period	$ 30,700

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)renewal_option	Dec. 31, 2018USD ($)
Lessee, Lease, Description [Line Items]
Option to extend lease	10 years
Option to extend existing lease	5 years
Number of periods | renewal_option	2
Cash paid for amounts included in measurement of lease liabilities	$ 9.1
Weighted average remaining lease term	5 years
Weighted average discount rate	5.90%
Lease payments for leases not yet commenced	$ 112.9
Operating leases not yet commenced		$ 112.9
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Operating lease commencement period	5 years
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	5 years
Operating lease commencement period	11 years

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating lease cost	$ 6,523
Variable lease cost	4,781
Total lease cost	$ 11,304

Leases - Schedule of Maturities

Leases - Schedule of Maturities for Operating Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
Remainder of 2019	$ 19,196
2020	28,550
2021	28,090
2022	24,565
2023	22,388
All future years	19,009
Total lease payments	141,798
Less: Imputed interest	(19,832)
Present value of lease liabilities	$ 121,966

Leases - Schedule of Future Min

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

Debt - Schedule of Revolving Cr

Debt - Schedule of Revolving Credit Facilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Outstanding borrowings on revolving credit facility	$ 246,028	$ 116,700
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum Borrowing Capacity	1,000,000
Outstanding borrowings on revolving credit facility	246,028	116,700
Line of Credit | Revolving Credit Facility | July 31, 2018
Debt Instrument [Line Items]
Maximum Borrowing Capacity	500,000
Outstanding borrowings on revolving credit facility	$ 167,279	116,700
Weighted Average Interest Rate	6.00%
Line of Credit | Revolving Credit Facility | January 31, 2019
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 500,000
Outstanding borrowings on revolving credit facility	$ 78,749	$ 0
Weighted Average Interest Rate	5.99%

Debt - Narrative (Detail)

Debt - Narrative (Detail) - USD ($)	Jan. 31, 2019	Jul. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Convertible Debt
Debt Instrument [Line Items]
Unamortized debt discount and debt issuance costs			$ 135,500,000	$ 144,400,000
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity			1,000,000,000
Extension of expiration period (up to)		2 years
Credit Agreement | Revolving Credit Facility | Citibank, N.A. | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 500,000,000
Current borrowing capacity			79,000,000
Revolving credit facility, initial term	2 years
July 31, 2018 | Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity			500,000,000
Current borrowing capacity			$ 177,300,000
Revolving credit facility, initial term		1 year

Debt - Schedule of Warehouse Li

Debt - Schedule of Warehouse Lines of Credit (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Warehouse lines of credit	$ 27,991	$ 33,018
Line of Credit
Debt Instrument [Line Items]
Maximum Borrowing Capacity	100,000
Warehouse lines of credit	27,991	33,017
Line of Credit | July 15, 2019
Debt Instrument [Line Items]
Maximum Borrowing Capacity	50,000
Warehouse lines of credit	$ 13,300	14,125
Weighted Average Interest Rate	5.00%
Line of Credit | June 29, 2019
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 50,000
Warehouse lines of credit	$ 14,691	$ 18,892
Weighted Average Interest Rate	5.00%

Debt - Schedule of Convertible

Debt - Schedule of Convertible Senior Notes (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 843,387
Fair Value	829,603	$ 784,799
Convertible Debt | July 1, 2023
Debt Instrument [Line Items]
Aggregate Principal Amount	373,750
Fair Value	$ 341,850	321,855
Stated Interest Rate	1.50%
Effective Interest Rate	6.99%
Convertible Debt | December 1, 2021
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 460,000
Fair Value	$ 470,911	446,200
Stated Interest Rate	2.00%
Effective Interest Rate	7.44%
Convertible Debt | December 15, 2020
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 9,637
Fair Value	$ 16,842	$ 16,744
Stated Interest Rate	2.75%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) $ in Millions	Dec. 31, 2018USD ($)
Federal
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards	$ 1,081.7
State
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards	$ 32.5

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, 2019	Dec. 31, 2018
Number of Shares Subject to Existing Options
Beginning Balance (in shares)	27,310,110
Granted (in shares)	6,155,283
Exercised (in shares)	(729,788)
Forfeited or cancelled (in shares)	(993,437)
Ending Balance (in shares)	31,742,168	27,310,110
Vested and exercisable ending balance (in shares)	16,791,512
Weighted- Average Exercise Price Per Share
Beginning Balance (usd per share)	$ 34.04
Granted (usd per share)	39.97
Exercised (usd per share)	18.59
Forfeited or cancelled (usd per share)	42.01
Ending Balance (usd per share)	35.30	$ 34.04
Vested and exercisable (usd per share)	$ 30.84
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted-Average Remaining Contractual Life, Outstanding	6 years 9 months 3 days	6 years 2 months 23 days
Weighted-Average Remaining Contractual Life, Vested and exercisable	4 years 9 months 29 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Aggregate Intrinsic Value, Outstanding	$ 122,262	$ 97,941
Aggregate Intrinsic Value Vested, and exercisable	$ 101,912

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, 2019	Mar. 31, 2018
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)	$ 16.77	$ 20.88
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	46.00%	43.00%
Risk-free interest rate	2.38%	2.52%
Weighted-average expected life	4 years 9 months	4 years 6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	47.00%	45.00%
Risk-free interest rate	2.53%	2.65%
Weighted-average expected life	5 years 3 months	5 years

Share-Based Awards - Option Awa

Share-Based Awards - Option Awards - Additional Information (Detail) $ in Millions	Mar. 31, 2019USD ($)
Option Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized cost of unvested share-based compensation awards	$ 229.5

Share-Based Awards - Summary _2

Share-Based Awards - Summary of Restricted Stock Units Activity (Detail) - Restricted Stock Units	3 Months Ended
	Mar. 31, 2019$ / sharesshares
Restricted Stock Units
Beginning balance (in shares) | shares	5,266,324
Granted (in shares) | shares	2,749,293
Vested (in shares) | shares	(496,347)
Forfeited or cancelled (in shares) | shares	(273,753)
Ending balance (in shares) | shares	7,245,517
Weighted- Average Grant- Date Fair Value
Unvested outstanding, beginning balance (usd per share) | $ / shares	$ 42.19
Granted (usd per share) | $ / shares	39.06
Vested (usd per share) | $ / shares	37.94
Forfeited or cancelled (usd per share) | $ / shares	40.44
Unvested outstanding, ending balance (usd per share) | $ / shares	$ 41.36

Share-Based Awards - Restricted

Share-Based Awards - Restricted Stock Units - Additional Information (Detail) $ in Millions	Mar. 31, 2019USD ($)
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 279.8

Share-Based Awards - Effects of

Share-Based Awards - Effects of Share Based Compensation in Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	Feb. 21, 2019	Mar. 31, 2019	Mar. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		$ 66,124	$ 30,741
Chief Executive Officer
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		26,400
Accelerated vesting period from departure date	18 months
Exercisable period from final date	90 days
Minimum | Chief Executive Officer
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Expected volatility	46.00%
Risk-free interest rate	2.47%
Weighted-average expected life	3 years 10 months 2 days
Maximum | Chief Executive Officer
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Expected volatility	47.00%
Risk-free interest rate	2.49%
Weighted-average expected life	5 years 3 months
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		881	955
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		5,650	5,162
Technology and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		15,508	11,542
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation		$ 44,085	$ 13,082

Net Loss Per Share - Antidiluti

Net Loss Per Share - Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
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)	25,689	30,206
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)	19,408	25,222
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)	5,860	4,346
Class A Common Stock | December 15, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total Class A common stock and Class C capital stock equivalents (in shares)	421	403
Class C Capital Stock | December 1, 2021
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	235

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Jun. 20, 2017USD ($)	Feb. 09, 2017USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Feb. 28, 2018claim	Sep. 30, 2017claim
Other Commitments [Line Items]
Outstanding surety bonds			$ 8,600,000	$ 8,900,000
VHT Vs Zillow Group Inc.
Other Commitments [Line Items]
Jury awarded damages	$ 4,100,000
VHT Vs Zillow Group Inc. | Actual Damages
Other Commitments [Line Items]
Jury awarded damages		$ 79,875
VHT Vs Zillow Group Inc. | Statutory Damages
Other Commitments [Line Items]
Jury awarded damages		$ 8,200,000
Class Action Lawsuits
Other Commitments [Line Items]
Number of pending claims | claim						2
Shareholder Derivative Lawsuits
Other Commitments [Line Items]
Number of pending claims | claim					4
Homes under contract to purchase that have not closed
Other Commitments [Line Items]
Value of homes under contract that have not closed			$ 140,200,000

Self-Insurance - Additional Inf

Self-Insurance - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Insurance [Abstract]
Percentage of cumulative medical claim under self insurance plan (percent exceeded)	125.00%
Limit of medical claim under self insurance plan (limit)	$ 1,000,000
Minimum amount of individual claim under self insurance plan	500,000
Liability for self-insured claims included in accrued compensation and benefits	$ 4,100,000	$ 3,900,000

Employee Benefit Plan - Additio

Employee Benefit Plan - Additional Information (Detail) - Zillow Merger - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Company's contribution based on employee contribution (up to)	4.00%
Company's expense related to its defined contribution 401(k) retirement plans	$ 4.9	$ 3.8

Segment Information and Reven_3

Segment Information and Revenue - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information and Reven_4

Segment Information and Revenue - Revenue Categories (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Revenue:
Total revenue		$ 454,104	$ 299,879
Costs and expenses:
Cost of revenue		151,348	23,919
Sales and marketing		161,587	137,291
Technology and development		107,770	93,933
General and administrative		95,774	56,073
Acquisition-related costs		352	0
Integration costs		0	27
Total costs and expenses		516,831	311,243
Loss from operations		(62,727)	(11,364)
Other income		9,168	2,446
Interest expense		(16,466)	(7,073)
Loss before income taxes		(70,025)	(15,991)
IMT
Revenue:
Total revenue		298,272	280,856
Costs and expenses:
Cost of revenue	[1]	24,251	22,594
Sales and marketing		126,654	128,747
Technology and development		87,969	85,917
General and administrative		70,850	50,187
Integration costs		0	27
Total costs and expenses		309,724	287,472
Loss from operations		(11,452)
Other income		0
Interest expense		0
Loss before income taxes		(11,452)	(6,616)
IMT | Premier Agent
Revenue:
Total revenue		217,735	213,732
IMT | Rentals
Revenue:
Total revenue		37,838	29,063
IMT | Other
Revenue:
Total revenue		42,699	38,061
IMT | Homes
Revenue:
Total revenue		0	0
IMT | Mortgages
Revenue:
Total revenue		0	0
Homes
Revenue:
Total revenue		128,472	0
Costs and expenses:
Cost of revenue	[1]	122,419	86
Sales and marketing		20,862	290
Technology and development		12,281	2,236
General and administrative		14,357	1,778
Integration costs		0	0
Total costs and expenses		169,919	4,390
Loss from operations		(41,447)
Other income		0
Interest expense		(3,758)
Loss before income taxes		(45,205)	(4,390)
Homes | Premier Agent
Revenue:
Total revenue		0	0
Homes | Rentals
Revenue:
Total revenue		0	0
Homes | Other
Revenue:
Total revenue		0	0
Homes | Homes
Revenue:
Total revenue		128,472	0
Homes | Mortgages
Revenue:
Total revenue		0	0
Mortgages
Revenue:
Total revenue		27,360	19,023
Costs and expenses:
Cost of revenue	[1]	4,678	1,239
Sales and marketing		14,071	8,254
Technology and development		7,520	5,780
General and administrative		10,567	4,108
Integration costs		352	0
Total costs and expenses		37,188	19,381
Loss from operations		(9,828)
Other income		313
Interest expense		(101)
Loss before income taxes		(9,616)	(358)
Mortgages | Premier Agent
Revenue:
Total revenue		0	0
Mortgages | Rentals
Revenue:
Total revenue		0	0
Mortgages | Other
Revenue:
Total revenue		0	0
Mortgages | Homes
Revenue:
Total revenue		0	0
Mortgages | Mortgages
Revenue:
Total revenue		$ 27,360	$ 19,023
[1]	Amortization of website development costs and intangible assets included in technology and development of $14,400 and $22,549 for the three months ended March 31, 2019 and 2018, respectively.

Segment Information and Reven_5

Segment Information and Revenue - Reconciliation of Total Segment Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Loss before income taxes	$ (70,025)	$ (15,991)
Corporate interest expense	(16,466)	(7,073)
Corporate other income	9,168	2,446
Consolidated loss before income taxes	(70,025)	(15,991)
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Loss before income taxes	(66,273)	(11,364)
Consolidated loss before income taxes	(66,273)	(11,364)
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Corporate interest expense	(12,607)	(7,073)
Corporate other income	$ 8,855	$ 2,446

Uncategorized Items - q12019for

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