Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Income Tax [Line Items]
Income tax benefit (expense)	$ (1,263,000)	$ 7,523,000	$ 4,258,000
Effective income tax rate reconciliation, state and local income taxes, amount	4,500,000
Income tax reconciliation change in deferred tax assets valuation allowance	273,800,000	125,000,000
Impairment and restructuring costs	56,828,000	76,800,000	0
Unrecognized tax benefits	74,978,000	49,094,000	39,432,000	$ 28,625,000
Research And Development
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards	133,200,000	88,800,000
Federal
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards	2,100,000,000	1,700,000,000
State
Schedule Of Income Tax [Line Items]
Net operating loss carryforwards	72,700,000	53,200,000
Trulia
Schedule Of Income Tax [Line Items]
Income tax benefit (expense)		9,700,000
Trulia | Trade names and trademarks
Schedule Of Income Tax [Line Items]
Impairment and restructuring costs	0	$ 71,500,000	$ 0
ShowingTime.com, Inc.
Schedule Of Income Tax [Line Items]
Income tax reconciliation change in deferred tax assets valuation allowance	$ (3,200,000)