Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of total capital expenditures incurred to total capital expenditures in the consolidated statements of cash flows
Capital expenditures incurred	$ 96,146	$ 92,141
Additions incurred in prior year but paid for in current period	20,004	9,465
Additions incurred but not paid for as of the end of the period	(24,452)	(19,479)
Capital expenditures per Consolidated Condensed Statements of Cash Flows	$ 91,698	$ 82,127