CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME
Rental income	$ 57,261	$ 49,808	$ 114,939	$ 99,805
Expenses:
Real estate taxes	6,648	5,899	13,151	11,378
Utility expenses	3,993	3,793	7,980	7,524
Other operating expenses	10,016	9,232	19,594	17,999
Depreciation and amortization	13,972	11,995	27,668	23,905
Acquisition related costs	105	245	139	294
General and administrative	3,299	2,680	6,548	5,682
Total expenses	38,033	33,844	75,080	66,782
Operating income	19,228	15,964	39,859	33,023
Interest and other income	5	6	16	14
Interest expense (including net amortization of debt premiums and deferred financing fees of $332, $335, $663 and $659, respectively)	(4,065)	(4,096)	(8,212)	(8,119)
Equity in earnings of an investee	79	76	155	121
Income from continuing operations before income tax expense	15,247	11,950	31,818	25,039
Income tax expense	(43)	(44)	(86)	(89)
Income from continuing operations	15,204	11,906	31,732	24,950
Discontinued operations:
Income from discontinued operations		48	30	63
Net gain on sale of properties from discontinued operations			8,168
Net income	15,204	11,954	39,930	25,013
Other comprehensive income (loss):
Equity in unrealized loss of an investee	(73)	(1)	(81)	(4)
Other comprehensive income (loss)	(73)	(1)	(81)	(4)
Comprehensive income	$ 15,131	$ 11,953	$ 39,849	$ 25,009
Weighted average common shares outstanding (in shares)	54,669	47,098	54,657	47,075
Per common share amounts:
Income from continuing operations (in dollars per share)	$ 0.28	$ 0.25	$ 0.58	$ 0.53
Income from discontinued operations (in dollars per share)			$ 0.15
Net income (in dollars per share)	$ 0.28	$ 0.25	$ 0.73	$ 0.53