Commitments and Contingencies Warranty Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		36 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Warranty Accrual Rollforward [Abstract]
Warranty reserves, beginning of period	$ 23,279	$ 30,303	$ 26,133	$ 27,732
Warranty expense on homes delivered during the period	3,353	2,882	9,195	8,094
Changes in estimates for pre-existing warranties	417	92	882	1,154
Settlements made during the period	(4,508)	(6,209)	(13,669)	(18,412)
Warranty reserves, end of period	22,541	27,068	22,541	27,068	$ 26,133
Charges related to stucco-related claims	0	$ 0	0	$ 8,500	$ 28,400
Estimated Repair Costs for Affected Homes	$ 5,600		$ 5,600