CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Revenue:
Rental and other income	$ 249,905	$ 226,210
Management, development and other fees	2,549	2,320
Total revenue	252,454	228,530
Expenses:
Operating expenses, excluding property taxes	65,905	63,767
Property taxes	24,530	24,140
Interest expense, net	33,626	42,971
Loss on extinguishment of debt	1,179
Depreciation expense	62,991	59,650
General and administrative expense	9,710	7,292
Total expenses	197,941	197,820
Equity in income of unconsolidated entities	2,175	503
Income from continuing operations	56,688	31,213
Discontinued operations:
Income (loss) from discontinued operations	921	(676)
Total discontinued operations	921	(676)
Net income	57,609	30,537
Net (income) loss attributable to noncontrolling interests	149	(196)
Net income attributable to common stockholders	57,758	30,341
Other comprehensive income:
Unrealized gain (loss) on cash flow hedges	11,008	(84)
Comprehensive income	$ 68,766	$ 30,257
Earnings per common share - basic:
Income from continuing operations attributable to common stockholders (in dollars per share)	$ 0.60	$ 0.36
Discontinued operations attributable to common stockholders (in dollars per share)	$ 0.01	$ (0.01)
Net income attributable to common stockholders (in dollars per share)	$ 0.61	$ 0.35
Earnings per common share - diluted:
Income from continuing operations attributable to common stockholders (in dollars per share)	$ 0.59	$ 0.36
Discontinued operations attributable to common stockholders (in dollars per share)	$ 0.01	$ (0.01)
Net income attributable to common stockholders (in dollars per share)	$ 0.60	$ 0.35
Dividends per common share: (in dollars per share)	$ 0.9700	$ 0.8925