Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Rental income	$ 295,340	$ 269,646	$ 195,496
Interest income from mortgage notes receivable and other income	4,304	4,792	7,585
Total revenues	299,644	274,438	203,081
Expenses:
Rental	95,307	88,760	65,662
General and administrative	21,741	20,879	16,008
Acquisition-related	8,843	2,130	11,317
Depreciation and amortization	116,418	107,542	78,561
Listing	22,573	0	0
Non-traded REIT	4,340	7,816	2,745
Redemption, termination, and release payment to former advisor	0	0	7,285
Total expenses	269,222	227,127	181,578
Income before other income (expense)	30,422	47,311	21,503
Interest expense (including amortization of deferred financing costs and debt premium/discount):
Interest related to debt	(40,382)	(39,613)	(26,725)
Interest related to derivative financial instruments and net change in fair value of derivative financial instruments	(12,611)	(2,279)	(2,816)
Debt extinguishment costs	(1,886)	0	0
Other income	89	174	119
Net (loss) income	(24,368)	5,593	(7,919)
Less: net (income) loss attributable to noncontrolling interests	(56)	(52)	16
Net (loss) income attributable to controlling interest	$ (24,424)	$ 5,541	$ (7,903)
Net (loss) income per share attributable to controlling interest - basic (usd per share)	$ (0.11)	$ 0.02	$ (0.05)
Net (loss) income per share attributable to controlling interest - diluted (usd per share)	$ (0.11)	$ 0.02	$ (0.05)
Weighted average number of shares outstanding
Basic (in shares)	222,713	223,900	165,953
Diluted (in shares)	222,713	224,392	165,953