Energy Services Accounts Receivable Securitization Facility - Trade Receivables Transferred and Sold (Details) - ESFC - USD ($)	6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable
Trade receivables transferred to ESFC during the period	$ 806,900,000	$ 633,700,000
ESFC trade receivables sold to the bank during the period	128,000,000	151,000,000
ESFC trade receivables - end of period	99,600,000	85,300,000	$ 44,800,000
Outstanding balance of trade receivables sold	$ 10,000,000	$ 0	$ 39,000,000