Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues:
Rental and other property	$ 150,170	$ 129,765	$ 296,565	$ 255,238
Management and other fees	3,234	2,796	6,182	5,240
Total revenues	153,404	132,561	302,747	260,478
Expenses:
Property operating, excluding real estate taxes	34,489	30,718	67,097	59,470
Real estate taxes	14,248	11,699	28,404	23,112
Depreciation	48,031	41,801	95,175	82,535
General and administrative	6,224	5,764	12,850	11,164
Cost of management and other fees	1,733	1,611	3,434	3,251
Total expenses	104,725	91,593	206,960	179,532
Earnings from operations	48,679	40,968	95,787	80,946
Interest expense before amortization	(26,325)	(24,659)	(51,536)	(49,316)
Amortization expense	(3,002)	(2,882)	(5,932)	(5,754)
Interest and other income	1,917	5,455	6,939	7,868
Equity income in co-investments	7,282	3,111	11,493	5,451
Gain (loss) on early retirement of debt	1,024	(1,450)	1,024	(1,450)
Gain on sale of land	0	0	1,503	0
Equity Method Investment, Realized Gain (Loss) on Remeasurement	0	21,947	0	21,947
Income from continuing operations	29,575	42,490	59,278	59,692
Income from discontinued operations	0	0	0	10,037
Net income	29,575	42,490	59,278	69,729
Net income attributable to noncontrolling interest	(3,261)	(4,044)	(6,393)	(7,193)
Net income attributable to controlling interest	26,314	38,446	52,885	62,536
Dividends to preferred stockholders	(1,368)	(1,368)	(2,736)	(2,736)
Net income available to common stockholders	24,946	37,078	50,149	59,800
Comprehensive income	35,355	39,983	66,094	69,575
Comprehensive income attributable to noncontrolling interest	(3,574)	(3,887)	(6,761)	(7,183)
Comprehensive income attributable to controlling interest	$ 31,781	$ 36,096	$ 59,333	$ 62,392
Basic:
Income from continuing operations (in dollars per share)	$ 0.67	$ 1.07	$ 1.35	$ 1.47
Income from discontinued operations (in dollars per share)	$ 0	$ 0	$ 0	$ 0.27
Net income available to common stockholders (in dollars per share)	$ 0.67	$ 1.07	$ 1.35	$ 1.74
Weighted average number of common shares outstanding during the period (in shares)	37,292,720	34,570,772	37,149,120	34,299,331
Diluted:
Income from continuing operations (in dollars per share)	$ 0.67	$ 1.07	$ 1.35	$ 1.47
Income from discontinued operations (in dollars per share)	$ 0	$ 0	$ 0	$ 0.27
Net income available to common stockholders (in dollars per share)	$ 0.67	$ 1.07	$ 1.35	$ 1.74
Weighted average number of common shares outstanding during the period (in shares)	37,390,987	34,708,240	37,241,968	34,430,571
Dividends per common share (in dollars per share)	$ 1.21	$ 1.10	$ 2.42	$ 2.2