Shareholders' Equity (Summary Of Dividends Declared And Paid Per Share) (Details) (USD $)	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010
Common Shares [Member]
Dividend declared, common share	$ 1.340	$ 1.320
Dividend paid, common share	$ 1.340	$ 1.320
5.417% Series 1 Cumulative Convertible Preferred [Member]
Dividend declared, preferred share	$ 0.677	$ 0.677
Dividend paid, preferred share	$ 0.677	$ 0.677

Aggregate dividends paid during the period for each share of common stock outstanding.

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

Reference 2: 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=6959260&loc=d3e187085-122770

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