Energy Services Accounts Receivable Securitization Facility - Trade Receivables Transferred and Sold (Details) - ESFC - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable
Trade receivables transferred to ESFC during the period	$ 392.6	$ 270.6
ESFC trade receivables sold to the bank during the period	25.0	48.0
ESFC trade receivables - end of period	135.4	101.0	$ 65.0
Outstanding balance of trade receivables sold	$ 10.0	$ 45.0	$ 2.0