Debt and Financing Activities (Accounts Receivable Sales Facility and Revolving Credit Facility) (Narrative) (Details) (USD $)	9 Months Ended		1 Months Ended		9 Months Ended					9 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Nov. 30, 2013 Accounts Receivable Sales Facility [Member]	May 31, 2013 Accounts Receivable Sales Facility [Member]	Dec. 31, 2013 Accounts Receivable Sales Facility [Member]	Dec. 31, 2012 Accounts Receivable Sales Facility [Member]	Mar. 31, 2013 Accounts Receivable Sales Facility [Member]	Nov. 30, 2013 Accounts Receivable Sales Facility [Member] Maximum [Member]	Oct. 31, 2013 Accounts Receivable Sales Facility [Member] Maximum [Member]	Dec. 31, 2013 Revolving Credit Facility [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Mar. 31, 2013 Revolving Credit Facility [Member]	Dec. 31, 2013 Revolving Credit Facility [Member] Maximum [Member]	Nov. 30, 2013 Revolving Credit Facility [Member] Maximum [Member]	Oct. 31, 2013 Revolving Credit Facility [Member] Maximum [Member]	Jan. 30, 2014 Subsequent Event [Member] Revolving Credit Facility [Member] Maximum [Member]
Line of Credit Facility [Line Items]
Repayments of lines of credit					$ 150,000,000	$ 1,525,000,000
Accounts receivable sales facility, expiration period			1 year	6 months
Ratio of indebtedness to net capital								0.65	0.565				0.565			0.65
Credit facility capacity					1,350,000,000					1,300,000,000
Facility expiration date					Nov. 15, 2014					Sep. 23, 2016
Contingent ratio of indebtedness to net capital														65.00%	56.50%
Credit facility, increase, additional borrowings					150,000,000	1,125,000,000				0	0
Proceeds from short-term borrowings	150,000,000	1,125,000,000
Repayments of short-term borrowings	150,000,000	1,525,000,000
Borrowings outstanding					0		0			0		0
Related securitized accounts receivable outstanding					$ 0		$ 0