Financing Activities (Details) (USD $)	1 Months Ended	3 Months Ended
	May 31, 2012 Y	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2012
Line of Credit Facility [Line Items]
Borrowings Outstanding		$ 0		$ 400,000,000
Accounts Receivable Sales Facility [Member]
Line of Credit Facility [Line Items]
Number of years for which accounts receivable sales facility was renewed	1
Facility Capacity		1,350,000,000
Facility Expiration Date		May 15, 2013
Borrowings During Period		0	0
Borrowings Outstanding		0		400,000,000
Securitized Receivable Balance		0		400,000,000
Repayments of Borrowings		400,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Capacity		1,300,000,000
Facility Expiration Date		Sep. 23, 2016
Borrowings During Period		0	0
Borrowings Outstanding		$ 0		$ 0