Federal and State Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011 Series B-1 [Member]	Dec. 31, 2010 Series B-1 [Member]	Dec. 31, 2011 Series C [Member]	Dec. 31, 2010 Series C [Member]	Dec. 31, 2012 Series D Cumulative Redeemable Preferred Shares [Member]	Dec. 31, 2011 Series D Cumulative Redeemable Preferred Shares [Member]	Dec. 31, 2011 Ordinary Dividends [Member] Series B-1 [Member]	Dec. 31, 2010 Ordinary Dividends [Member] Series B-1 [Member]	Dec. 31, 2011 Ordinary Dividends [Member] Series C [Member]	Dec. 31, 2010 Ordinary Dividends [Member] Series C [Member]	Dec. 31, 2012 Ordinary Dividends [Member] Series D Cumulative Redeemable Preferred Shares [Member]	Dec. 31, 2011 Ordinary Dividends [Member] Series D Cumulative Redeemable Preferred Shares [Member]	Dec. 31, 2011 Capital Gains 15% Rate [Member] Series B-1 [Member]	Dec. 31, 2010 Capital Gains 15% Rate [Member] Series B-1 [Member]	Dec. 31, 2011 Capital Gains 15% Rate [Member] Series C [Member]	Dec. 31, 2010 Capital Gains 15% Rate [Member] Series C [Member]	Dec. 31, 2012 Capital Gains 15% Rate [Member] Series D Cumulative Redeemable Preferred Shares [Member]	Dec. 31, 2011 Capital Gains 15% Rate [Member] Series D Cumulative Redeemable Preferred Shares [Member]	Dec. 31, 2011 Nontaxable Distribution [Member] Series B-1 [Member]	Dec. 31, 2010 Nontaxable Distribution [Member] Series B-1 [Member]	Dec. 31, 2011 Nontaxable Distribution [Member] Series C [Member]	Dec. 31, 2010 Nontaxable Distribution [Member] Series C [Member]	Dec. 31, 2012 Nontaxable Distribution [Member] Series D Cumulative Redeemable Preferred Shares [Member]	Dec. 31, 2011 Nontaxable Distribution [Member] Series D Cumulative Redeemable Preferred Shares [Member]
Summary cash dividends per series preferred share for individual shareholder
Dividends paid or accrued per Preferred Share	$ 0.40625	$ 1.30	$ 1.22	$ 1.30	$ 2.03	$ 2.31	$ 0.21	$ 1.30	$ 2.03	$ 1.30	$ 2.03	$ 2.31	$ 0.21