Dispositions of Real Estate and Discontinued Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2011 item	Jun. 30, 2012 item	Jun. 30, 2011 item	Mar. 31, 2012 Medical office	Jun. 30, 2012 Medical office
Dispositions of Real Estate
Total consideration for disposition of real estate		$ 7,238		$ 7,238	$ 7,238
Operating income from discontinued operations
Rental and related revenues	581	246	1,158
Depreciation and amortization expenses	238	35	476
Operating expenses	6	2	7
Other (income) expense, net		72	(3)
Income, net of income taxes	337	137	678
Gain on sales of real estate, net of income taxes		$ 2,856
Number of properties included in discontinued operations	4	1	4