Summary of Significant Accounting Policies - Additional Information (Detail)		12 Months Ended
	Aug. 14, 2015 shares	Dec. 31, 2015 USD ($) Categories Customer shares	Dec. 31, 2014 USD ($) Customer	Dec. 31, 2013 USD ($) Customer
Schedule Of Significant Accounting Policies [Line Items]
Business acquisition, effective date		Feb. 17, 2015
Stock split description		Outstanding equity awards to purchase or acquire shares of Class A common stock were proportionately adjusted to relate to one share of Class A common stock and two shares of Class C capital stock for each share of Class A common stock subject to the awards as of the record date, and the exercise prices of any such awards were also proportionately allocated between Class A common stock and Class C capital stock.
Stock split ratio	3
Other than temporary impairment loss		$ 0	$ 0
Amortization period, spread on perpetual rights contracts		2 years
Number of revenue categories | Categories		2
Sale of product for fixed subscription, description		Trulia real estate products included in real estate revenue are primarily sold on a fixed fee subscription basis, and include Trulia Local Ads, Trulia Mobile Ads, Trulia Pro with featured listings and Trulia Seller Ads. Prior to the August 2015 integration of certain of Zillow’s and Trulia’s advertising products, Trulia Local Ads and Trulia Mobile Ads enabled real estate professionals to promote themselves on Trulia’s search results pages and property details pages for a local market area. Real estate professionals purchased subscriptions to these products based upon their specified market share for a city or zip code, at a fixed monthly price, for periods ranging from one month to one year, with pricing depending on demand, location, and the percentage of market share purchased. Following the August 2015 agent advertising product integration, Trulia Local Ads and Trulia Mobile Ads products are no longer sold by Zillow Group. Trulia’s featured listings product allows real estate professionals to receive prominent placement of their listings in Trulia’s search results. Real estate professionals sign up for new subscriptions to this product at a fixed monthly price for periods that generally range from six months to 12 months. Trulia Seller Ads enable real estate professionals to generate leads from consumers interested in selling their homes.
Number of customers generating more than 10% of total revenue | Customer		0	0	0
Research and development expenses		$ 198,565,000	$ 84,669,000	$ 48,498,000
Advertising expenses		$ 103,400,000	$ 73,100,000	$ 38,700,000
Trulia
Schedule Of Significant Accounting Policies [Line Items]
Business acquisition, effective date		Feb. 17, 2015
Minimum | Customer Concentration Risk [Member] | Sales Revenue, Net [Member]
Schedule Of Significant Accounting Policies [Line Items]
Percentage of revenue		10.00%	10.00%	10.00%
First Set Of Product [Member]
Schedule Of Significant Accounting Policies [Line Items]
Purchase subscriptions to the products, maximum period		1 year
Purchase subscriptions to the products, minimum period		1 month
Second Set of Product
Schedule Of Significant Accounting Policies [Line Items]
Purchase subscriptions to the products, maximum period		12 months
Purchase subscriptions to the products, minimum period		6 months
Class C Capital Stock
Schedule Of Significant Accounting Policies [Line Items]
Dividend paid in shares for each class of common stock held as of record date | shares	2	2
Stock split description		On August 14, 2015, Zillow Group completed a stock dividend in the form of two shares of Class C capital stock for each share of Class A common stock and Class B common stock outstanding as of July 31, 2015. The stock dividend had the effect of a 3-for-1 stock split.
Technology and Development
Schedule Of Significant Accounting Policies [Line Items]
Research and development expenses		$ 163,800,000	$ 72,900,000	$ 41,700,000
Software Development
Schedule Of Significant Accounting Policies [Line Items]
Amortization period		1 year
Purchased Content | Minimum
Schedule Of Significant Accounting Policies [Line Items]
Amortization period		2 years
Purchased Content | Maximum
Schedule Of Significant Accounting Policies [Line Items]
Amortization period		9 years