Segment Reporting (Schedule of Information for Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Rental and parking expenses	$ (7,391)	$ (6,639)
Income from operations	20,570	26,384
General and administrative expenses	(1,683)	(1,581)
Change in fair value of contingent consideration	1,140	(120)
Asset management fees	(4,819)	(4,787)
Depreciation and amortization	(18,067)	(16,999)
Other interest and dividend income	563	2,822
Interest expense, net	(8,665)	(10,614)
Provision for loan losses	(2,484)	0
Net income	9,984	18,592
Operating Segments [Member]
Segment Reporting Information [Line Items]
Rental, parking and tenant reimbursement revenue	51,390	56,510
Rental and parking expenses	(7,391)	(6,639)
Income from operations	43,999	49,871
Operating Segments [Member] | Data Centers [Member]
Segment Reporting Information [Line Items]
Rental, parking and tenant reimbursement revenue	29,694	28,662
Rental and parking expenses	(4,784)	(4,823)
Income from operations	24,910	23,839
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Rental, parking and tenant reimbursement revenue	21,696	27,848
Rental and parking expenses	(2,607)	(1,816)
Income from operations	$ 19,089	$ 26,032