Earnings Per Common Share Calculation of numerator and denominator in eps table (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share Disclosure [Line Items]
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	$ 30,040	$ 18,621	$ 73,930	$ 55,062
Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Redeemable	(2,229)	(1,597)	5,710	4,730
Net Income (Loss) Available to Common Stockholders, Basic	25,483	17,860	63,582	52,883
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	2,905	0	6,657
Amounts allocated to dilutive securities	2,229	1,597	5,710	4,730
Net income (loss) available for Common Shares – fully diluted	27,712	19,457	69,292	57,613
Weighted average Common Shares outstanding – basic	83,234	83,021	83,175	83,024
Employee stock options and restricted shares	656	651	654	630
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Preferred Stock	7,530	7,456	7,582	7,456
Weighted average Common Shares outstanding - fully diluted	91,420	91,128	91,411	91,110
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.31	$ 0.18	$ 0.76	$ 0.55
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	$ 0.00	$ 0.04	$ 0.00	$ 0.09
Net income available for Common Shares	$ 0.31	$ 0.22	$ 0.76	$ 0.64
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.30	$ 0.18	$ 0.76	$ 0.55
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	$ 0.00	$ 0.03	$ 0.00	$ 0.08
Net income available for Common Shares	$ 0.30	$ 0.21	$ 0.76	$ 0.63
Cumulative Series C Six Point Seven Five Percent Redeemable Perpetual Preferred Stock [Member]
Earnings Per Share Disclosure [Line Items]
Redeemable Preferred Stock Dividends	(2,328)	(2,329)	(4,638)	(4,640)
Segment, Continuing Operations [Member]
Earnings Per Share Disclosure [Line Items]
Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Redeemable	(2,229)	(1,337)	(5,710)	(4,196)
Net Income (Loss) Available to Common Stockholders, Basic	25,483	14,955	63,582	46,226
Amounts allocated to dilutive securities	2,229	1,337	5,710	4,196
Net income (loss) available for Common Shares – fully diluted	$ 27,712	$ 16,292	$ 69,292	$ 50,422