Dividends (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Dividends [Abstract]
Total dividends per share for the period	$ 1.425	$ 1.417	$ 1.406
Cash dividend	$ (286,478)us-gaap_DividendsCommonStockCash	$ (281,204)us-gaap_DividendsCommonStockCash	$ (273,822)us-gaap_DividendsCommonStockCash

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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