Dividends (Details) (USD $)	12 Months Ended
Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2009
Notes to Financial Statements [Abstract]
Total dividends per share for the period	$ 1.374	$ 1.359	$ 1.346
Total dividends for the period	$ (256,811,000)	$ (249,556,000)	$ (246,657,000)

Common stock cash dividend declared by an entity during the period. This element includes paid and unpaid dividends declared during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Name:	us-gaap_DividendsCommonStockCash
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration