Federal Income Tax Considerations (Schedule Of Cash Dividends Distributed To Common Shareholders) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Note [Line Items]
Ordinary income	92.80%	100.00%	79.10%
Capital gain distributions	7.20%	0.00%	20.90%
Total	100.00%	100.00%	100.00%