Miscellaneous Financial Information (Unaudited), Dividends and Preferred Stock Redemption (Details) (Common Stock [Member], USD $)	1 Months Ended
Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Apr. 30, 2011	Jan. 24, 2013 Subsequent Event [Member]
Dividends Payable [Line Items]
Dividend payable (in dollars per share)					$ 0.3125	$ 0.28	$ 0.3375
Common Stock, Dividends, Per Share, Declared	$ 0.3375	$ 0.3375	$ 0.3125	$ 0.3125

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 32

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant