Fair Value Of Financial Assets And Liabilities (Carrying Value And Fair Value Of Debt) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Mar. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commercial Paper	$ 406,861	$ 0
Carrying value, Debt	1,770,808	1,852,862
Fair value	2,234,952	1,899,531
Total debt	2,177,669	1,852,862
Revolving Credit Borrowings [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value, Debt	47,499	378,209
Fair value	47,499	381,235
2013 Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value, Debt	306,550	305,019
Fair value	311,798	308,716
2014 Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value, Debt	399,736	399,664
Fair value	423,412	419,899
2015 Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value, Debt	249,717	249,660
Fair value	256,534	249,430
2016 Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value, Debt	249,691	0
Fair value	256,987	0
Senior Subordinated Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value, Debt	215,446	215,446
Fair value	229,450	235,105
Trade Receivables Securitization [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value, Debt	295,000	295,000
Fair value	295,000	295,000
Acquisition And Other Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying value, Debt	7,169	9,864
Fair value	7,411	10,146
Commercial Paper [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value	$ 406,861	$ 0