Equity, Capital and Other Interests Text (Details) (USD $)	3 Months Ended
	Mar. 31, 2012
Common Stock Capital Shares Reserved For Future Issuance Under Share Offering Program	17,000,000
Common Shares Added To Atm Program	5,700,000
Stock Issued During Period, Shares, New Issues	2,078,310
Average Price Per Common Share Issued	$ 59.47
Stock Issued During Period, Value, New Issues	$ 123,601,393
Units Issued During Period New Issues	2,078,310
Additional Common Shares Authorized	7,094,004
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 464,600,000
Stock Repurchased And Retired	0