Basis of Presentation and Summary of Significant Accounting Policies - Business Combinations (Details) - Venture Homes $ in Millions	Jul. 13, 2018 USD ($) home lot Community	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Purchase price, net of cash acquired	$ 61.3
Purchase price paid, net cash acquired		$ 57.3
Remaining payments due		$ 4.0
Number of active communities | Community	27
Number of homes in backlog | home	48
Number of model homes in backlog | home	6
Inventory acquired	$ 56.0
Intangible Assets, Net (Including Goodwill)	10.6
Other assets acquired	0.7
Accounts payable	5.5
Other liabilities assumed	$ 0.2
Minimum
Business Acquisition [Line Items]
Number of lots acquired | lot	1,100