Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:
Rental and other property	$ 152,945	$ 134,518	$ 448,318	$ 388,642
Management and other fees	2,957	3,072	9,139	8,312
Total revenues	155,902	137,590	457,457	396,954
Expenses:
Property operating, excluding real estate taxes	36,002	32,763	102,790	91,828
Real estate taxes	14,561	12,310	42,852	35,326
Depreciation	48,438	42,897	143,320	125,137
General and administrative	6,075	5,276	18,925	16,440
Cost of management and other fees	1,613	1,642	5,047	4,893
Total expenses	106,689	94,888	312,934	273,624
Earnings from operations	49,213	42,702	144,523	123,330
Interest expense before amortization	(26,187)	(25,064)	(77,724)	(74,380)
Amortization expense	(3,005)	(2,927)	(8,937)	(8,681)
Interest and other income	2,387	3,003	9,326	10,869
Equity income in co-investments	40,802	3,547	52,295	8,998
(Loss) gain on early retirement of debt	(178)	(1,211)	846	(2,661)
Gain on sale of land	0	0	1,503	0
Gain on remeasurement of co-investment	0	0	0	21,947
Income from continuing operations	63,032	20,050	121,832	79,422
Income from discontinued operations	12,843	172	13,321	10,528
Net income	75,875	20,222	135,153	89,950
Net income attributable to noncontrolling interest	(5,719)	(2,635)	(12,112)	(9,827)
Net income attributable to controlling interest	70,156	17,587	123,041	80,123
Dividends to preferred stockholders	(1,368)	(1,368)	(4,104)	(4,104)
Net income available to common stockholders	68,788	16,219	118,937	76,019
Comprehensive income	76,112	16,462	142,206	86,034
Comprehensive income attributable to noncontrolling interest	(5,732)	(2,407)	(12,493)	(9,589)
Comprehensive income attributable to controlling interest	$ 70,380	$ 14,055	$ 129,713	$ 76,445
Basic:
Income from continuing operations (in dollars per share)	$ 1.52	$ 0.45	$ 2.86	$ 1.90
Income from discontinued operations (in dollars per share)	$ 0.32	$ 0.01	$ 0.34	$ 0.29
Net income available to common stockholders (in dollars per share)	$ 1.84	$ 0.46	$ 3.20	$ 2.19
Weighted average number of common shares outstanding during the period (in shares)	37,320,562	35,600,772	37,206,895	34,736,311
Diluted:
Income from continuing operations (in dollars per share)	$ 1.52	$ 0.44	$ 2.85	$ 1.90
Income from discontinued operations (in dollars per share)	$ 0.32	$ 0.01	$ 0.34	$ 0.28
Net income available to common stockholders (in dollars per share)	$ 1.84	$ 0.45	$ 3.19	$ 2.18
Weighted average number of common shares outstanding during the period (in shares)	37,436,983	35,699,666	37,295,691	34,834,076
Dividends per common share (in dollars per share)	$ 1.21	$ 1.10	$ 3.63	$ 3.30