Revolving Credit Facilities, Lines Of Credit And Short-Term Borrowings (Summary Of The Borrowings Outstanding And Capacity Available Under The Facility) (Details) (USD $)	Mar. 31, 2012
Summary of the borrowings outstanding and capacity available under the facility
Capacity	$ 3,500,000,000
Borrowings	1,465,000,000
Letters of Credit	8,000,000
Capacity Available	$ 2,027,000,000