Debt and Financing Activities (Accounts Receivable Sales Facility and Revolving Credit Facility) (Narrative) (Details) (USD $)	6 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2014
Accounts Receivable Sales Facility
Line of Credit Facility [Line Items]
Credit facility capacity	$ 1,350,000,000
Proceeds from lines of credit	0	150,000,000
Repayments of lines of credit		150,000,000
Borrowings outstanding	0		0
Credit facility expiration date	Nov. 15, 2014
Credit facility covenant compliance	we were in compliance with all covenants		we were in compliance with all covenants
Related accounts receivable outstanding	0		0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility capacity	1,300,000,000
Proceeds from lines of credit	0	0
Borrowings outstanding	$ 0		$ 0
Credit facility expiration date	Sep. 23, 2016
Credit facility interest rate description	bear interest based upon either the London Interbank Offered Rate or a prime rate