Net Income Per Common Share (Details) (USD $)	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Net Income Per Common Share [Abstract]
Income from continuing operations available to common stockholders	$ 13,307,000		$ 8,016,000
Income from continuing operations available to common stockholders (in shares)	34,027,890		31,465,817
Income from continuing operations available to common stockholders (in dollars per share)	$ 0.39		$ 0.25
Income from discontinued operations	9,415,000		402,000
Income from discontinued operations (in shares)	34,028,000		31,466,000
Income from discontinued operations (in dollars per share)	$ 0.28		$ 0.02
Income available to common stockholders	22,722,000		8,418,000
Income available to common stockholders (in dollars per share)	$ 0.67		$ 0.27
Effect of Dilutive Securities	0		0
Effect of Dilutive Securities (in shares)	124,000	[1],[2]	81,000	[1],[2]
Income from continuing operations available to common stockholders	13,307,000		8,016,000
Adjusted income from continuing operations available to common stockholders ( 1 ) (in shares)	34,152,000		31,547,000
Adjusted income from continuing operations available to common stockholders ( 1 ) (in dollars per share)	$ 0.39		$ 0.25
Adjusted income from discontinued operations available to common stockholders	9,415,000		402,000
Adjusted income from discontinued operations available to common stockholders (in shares)	34,152,000		31,547,000
Adjusted income from discontinued operations available to common stockholders (in dollars per share)	$ 0.28		$ 0.02
Total income (Diluted)	22,722,000		8,418,000
Total income per common share amount (in dollars per share)	$ 0.67		$ 0.27
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income allocated to convertible limited partnership units	$ 1,600,000		$ 600,000
Convertible Limited Partnership Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted convertible limited partnership units	2,245,166		2,240,639
Anti-dilutive securities (in shares)	2,245,166		2,240,639
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted convertible limited partnership units	137,032		36,750
Anti-dilutive securities (in shares)	137,032		36,750

[1] Weighted average convertible limited partnership units of 2,245,166 and 2,240,639, which includes vested Series Z incentive units, for the three months ended March 31, 2012, and 2011 respectively, were not included in the determination of diluted EPS because they were anti-dilutive. The Company has the ability to redeem DownREIT limited partnership units for cash and does not consider them to be potentially dilutive securities. Stock options of 137,032 and 36,750 for the three months ended March 31, 2012 and 2011, respectively, were not included in the diluted earnings per share calculation because the exercise prices of the options were greater than the average market price of the common shares for the three months ended and, therefore, were anti-dilutive. All shares of cumulative convertible preferred stock Series G have been excluded in diluted earnings per share for the three months ended March 31, 2012 and 2011, as the effect was anti-dilutive.

[2] Net income allocated to convertible limited partnership units, which includes vested Series Z units, aggregating $1.6 million and $0.6 million for the three months ended March 31, 2012 and 2011 respectively, have been excluded from income available to common stock holders for the calculation of net income per common share since these units are excluded from the diluted weighted average common shares for the period as the effect was anti-dilutive.