Impairments (Details) (USD $)	12 Months Ended		12 Months Ended			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2011 Delphis	Dec. 31, 2013 Delphis	Dec. 31, 2012 Delphis	Dec. 31, 2013 Medical office item	Dec. 31, 2012 Medical office	Dec. 31, 2012 Life science
Impairments
Number of properties disposed						2
Total consideration for disposition of real estate						$ 6,000,000	$ 7,000,000	$ 18,000,000
Impairment charges	(7,878,000)					1,000,000		7,900,000
Carrying value of aggregate investments	10,448,752,000	10,544,110,000				7,000,000
Carrying value, land	1,838,613,000	1,822,862,000						26,000,000
Provision for losses (impairment)			15,000,000
Loans receivable, before Impairment	147,264,000	147,669,000	91,000,000
Loans receivable, after Impairment			$ 76,000,000	$ 18,100,000	$ 30,700,000