Description of Business and Summary of Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended
	Aug. 02, 2017 USD ($) $ / shares shares	Jul. 10, 2017	Apr. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	May 31, 2016 USD ($)	Dec. 31, 2014 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reverse split of shares, conversion ratio		3
Common stock issued upon conversion (in shares) | shares	55,422,002
Conversion basis	1
Security deposit							$ 5,424
Proceeds from landlord reimbursements			$ 8,470
Home inventories				$ 3,382
Home inventories, held-for-sale				2,335
Home inventories, in process				1,047
Capitalized software development costs				$ 4,619	$ 3,194	$ 2,824
Intangible assets, useful life				10 years
Goodwill				$ 9,186	9,186
NOL carryforward, decrease				1,506
Allowance for doubtful accounts receivable				160	150
Charges to allowance for doubtful accounts				81	290
Write-offs				71	140
Advertising costs				21,902	17,570	8,394
Advertising production costs				1,609	1,640	1,661
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit				235,430	(563,734)	(495,713)		$ (370,595)
Deferred offering costs				0	720
Initial public offering costs				3,708
Loans held for sale				1,891	0
Cumulative stock-based compensation adjustment				0
Additional Paid-in Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit				364,352	0	0		0
Initial public offering costs				3,708
Cumulative stock-based compensation adjustment				522
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' deficit				(129,003)	(563,749)	$ (495,727)		$ (370,608)
Cumulative stock-based compensation adjustment				$ (522)
Accounting Standards Update 2016-09 | Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative stock-based compensation adjustment					522
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life				2 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life				7 years
IPO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shares sold in offering (in shares) | shares	10,615,650
Share price (in dollars per share) | $ / shares	$ 15.00
Net proceeds from stock offering	$ 144,380
Deferred offering costs					$ 720
IPO | Additional Paid-in Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Initial public offering costs				$ 3,708
Over-Allotment Option
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Shares sold in offering (in shares) | shares	1,384,650
Research Tax Credit Carryforward
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Research and development credits, decrease				$ 32
Software and Software Development Costs | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life				1 year
Software and Software Development Costs | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life				3 years