Inventory - Impairments and Lot Option Abandonment Charges, by Reportable Segment (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) lot Community	Jun. 30, 2018 USD ($)
Real Estate, Write-down or Reserve [Line Items]
Number of properties included in land held for sale | Community			6
Land Held for Sale	$ 0	$ 168	$ 38,588	$ 168
Total impairment and abandonment charges	0	168	148,618	618
Continuing Operations
Real Estate, Write-down or Reserve [Line Items]
Impairment charges on projects in progress	0	0	110,030	0
Discontinued Operations
Real Estate, Write-down or Reserve [Line Items]
Land Held for Sale	0	0	0	450
Total impairment and abandonment charges	200			600
West Segment
Real Estate, Write-down or Reserve [Line Items]
Land Held for Sale	0	0	37,963	0
West Segment | Continuing Operations
Real Estate, Write-down or Reserve [Line Items]
Impairment charges on projects in progress	0	0	92,912	0
East Segment
Real Estate, Write-down or Reserve [Line Items]
Land Held for Sale	0	168	0	168
Southeast Segment | Continuing Operations
Real Estate, Write-down or Reserve [Line Items]
Impairment charges on projects in progress	0	0	858	0
Corporate and unallocated | Continuing Operations
Real Estate, Write-down or Reserve [Line Items]
Impairment charges on projects in progress	0	0	16,260	0
Land Held for Sale	$ 0	$ 0	$ 625	$ 0
CALIFORNIA
Real Estate, Write-down or Reserve [Line Items]
Number of lots | lot			732