Energy Services Accounts Receivable Securitization Facility - Trade Receivables Transferred and Sold (Details) - ESFC - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable
Trade receivables transferred to ESFC during the period	$ 270.6	$ 246.4
ESFC trade receivables sold to the bank during the period	48.0	66.0
ESFC trade receivables - end of period	101.0	81.4	$ 44.8
Outstanding balance of trade receivables sold	$ 45.0	$ 35.0	$ 39.0