Fair Value Of Financial Assets And Liabilities (Carrying Value And Fair Value Of Debt) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Mar. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	$ 2,012,268	$ 1,772,287
Total Debt, Carrying Value	2,296,573	2,160,739
Trade receivables securitization [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	295,000	295,000
Senior Subordinated Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	215,446	215,446
Other long-term debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	2,888	6,150
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	2,368,923	2,237,065
Estimate of Fair Value, Fair Value Disclosure [Member] | Trade receivables securitization [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	295,000	295,000
Estimate of Fair Value, Fair Value Disclosure [Member] | Revolving Credit Borrowings [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	46,135	49,810
Estimate of Fair Value, Fair Value Disclosure [Member] | 2.85% Senior Notes Maturing October 2013 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	308,915	314,881
Estimate of Fair Value, Fair Value Disclosure [Member] | 4.5% Senior Notes Maturing September 2014 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	423,890	429,530
Estimate of Fair Value, Fair Value Disclosure [Member] | 3.25% Senior Notes Due October 2015 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	263,459	260,325
Estimate of Fair Value, Fair Value Disclosure [Member] | 2.95% Senior Notes Maturing June 2016 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	263,747	257,821
Estimate of Fair Value, Fair Value Disclosure [Member] | Senior Subordinated Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	232,412	234,836
Estimate of Fair Value, Fair Value Disclosure [Member] | 2.90% Senior Notes Maturing November 2022 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	248,024	0
Estimate of Fair Value, Fair Value Disclosure [Member] | Other long-term debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	3,036	6,410
Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial paper [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value of Debt	284,305	388,452
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Debt, Carrying Value	2,296,573	2,160,739
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Trade receivables securitization [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	295,000	295,000
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Revolving Credit Borrowings [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	46,135	49,810
Carrying (Reported) Amount, Fair Value Disclosure [Member] | 2.85% Senior Notes Maturing October 2013 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	303,689	306,677
Carrying (Reported) Amount, Fair Value Disclosure [Member] | 4.5% Senior Notes Maturing September 2014 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	399,832	399,760
Carrying (Reported) Amount, Fair Value Disclosure [Member] | 3.25% Senior Notes Due October 2015 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	249,792	249,736
Carrying (Reported) Amount, Fair Value Disclosure [Member] | 2.95% Senior Notes Maturing June 2016 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	249,761	249,708
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Senior Subordinated Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	215,446	215,446
Carrying (Reported) Amount, Fair Value Disclosure [Member] | 2.90% Senior Notes Maturing November 2022 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	249,725	0
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Other long-term debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Value	2,888	6,150
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commercial paper [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commercial Paper, Carrying Value	$ 284,305	$ 388,452