Accounts Receivable Facility (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2016	Nov. 30, 2015
Financing Receivable, Recorded Investment [Line Items]
Receivables Facility, maximum amount available based on receivables sold to investors, percent	50.00%
Document Period End Date	Sep. 30, 2016
Installment Lease Receivables, Net Book Value	$ 1,300
Proceeds from Accounts Receivable Securitization	1,200
Deferred purchase price from sale of receivables	(400)	$ 1,198
cash paid to purchasers under receivables facility	185
Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Cash received for sale of receivables under receivables facility	40
Cash Flows Between Transferor and Transferee, Proceeds from Collections Reinvested in Revolving Period Transfers	255
Accounts Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Maximum Funding Limit				$ 4,300
Receivables Facility, Amount of Funds Available	114
Deferred purchase price from sale of receivables	$ 1,600		$ 1,200