Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Reconciliation of total capital expenditures incurred to total capital expenditures in the consolidated statements of cash flows
Capital expenditures incurred	$ 321,588	$ 315,735
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	(18,934)	(24,925)
Capital expenditures per the Condensed Consolidated Statements of Cash Flows	$ 322,658	$ 300,275