Supplemental Cash Flow Information - Supplemental Disclosure of Non-cash Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Supplemental disclosure of non-cash activity:
Non-cash land acquisitions	$ 0	$ 5,197
Land acquisitions for debt	0	5,555
Supplemental disclosure of cash activity:
Interest payments	10,766	11,824
Income tax payments	0	178
Tax refunds received	39	4
Cash, Cash Equivalents, and Short-term Investments	177,812	158,623	$ 292,147
Restricted Cash and Cash Equivalents	12,082	15,963	12,462
Cash, Cash Equivalents, and Restricted Cash	$ 189,894	$ 174,586	$ 304,609	$ 243,276