Inventory - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019 USD ($) home lot Community	Mar. 31, 2018 USD ($) Community	Mar. 31, 2019 USD ($) home Community	Mar. 31, 2018 USD ($) Community	Sep. 30, 2018 USD ($) home
Inventory Disclosure [Abstract]
Number of substantially completed homes unsold | home	159		159		240
Total value of substantially completed homes | $	$ 60,000		$ 60,000		$ 84,800
Threshold number of homes below a minimum threshold of profitability | home			10
Impairment and abandonment charges | $	$ 147,611	$ 0	$ 148,618
Properties land held for sale and impaired properties	15
Number of Communities Impaired	9		10
Real Estate Properties [Line Items]
Number of communities on watch list	12	2	12	2
Number of communities requiring further analysis	9	0	9	0
Inventory impairment charge | $	$ 109,023		$ 110,030
Land Held for Sale | $	$ 38,588	$ 0	$ 38,588	$ 0
Number of properties included in land held for sale	6
West Segment
Real Estate Properties [Line Items]
Number of communities on watch list	12		12
Number of communities requiring further analysis	9		9
Land Held for Sale | $	$ 37,963	$ 0	$ 37,963	$ 0
Southern California market
Real Estate Properties [Line Items]
Number of communities requiring further analysis	9		9
Inventory impairment charge | $	$ 109,000
Number of lots | lot	839
Northern and Southern California market
Real Estate Properties [Line Items]
Number of lots | lot	732
Land Held for Sale | $	$ 38,600
Number of properties included in land held for sale			6