CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Rental income	$ 50,455	$ 39,228
Expenses:
Real estate taxes	5,533	4,457
Utility expenses	3,835	3,507
Other operating expenses	8,853	6,921
Depreciation and amortization	12,072	8,386
Acquisition related costs	49	829
General and administrative	3,039	2,343
Total expenses	33,381	26,443
Operating income	17,074	12,785
Interest and other income	8	15
Interest expense (including net amortization of debt premiums and deferred financing fees of $324 and $259, respectively)	(4,023)	(2,537)
Equity in earnings of an investee	45	37
Income before income tax expense	13,104	10,300
Income tax expense	(45)	(46)
Net income	13,059	10,254
Other comprehensive income:
Equity in unrealized (loss) gain of an investee	(1)	4
Other comprehensive income	(1)	4
Comprehensive income	$ 13,058	$ 10,258
Weighted average common shares outstanding (in shares)	47,052	40,501
Net income per common share (in dollars per share)	$ 0.28	$ 0.25