Schedule III - Real Estate and Accumulated Depreciation (Details) (USD $) In Thousands, unless otherwise specified						12 Months Ended
	Dec. 31, 2012 property		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Medical office/outpatient [Member] Property		Dec. 31, 2012 Medical office/outpatient [Member] Minimum [Member]	Dec. 31, 2012 Medical office/outpatient [Member] Maximum [Member]	Dec. 31, 2012 Inpatient [Member] Property		Dec. 31, 2012 Inpatient [Member] Minimum [Member]	Dec. 31, 2012 Inpatient [Member] Maximum [Member]	Dec. 31, 2012 Other [Member] Property		Dec. 31, 2012 Other [Member] Minimum [Member]	Dec. 31, 2012 Other [Member] Maximum [Member]	Dec. 31, 2012 Real Estate [Member] Property		Dec. 31, 2012 Land Held for Development [Member] Property		Dec. 31, 2012 Corporate Property [Member] Property		Dec. 31, 2012 Owned Property [Member] Property
Summary of real estate properties
Number of Properties	202					178				15				10				203		0		0		203
State						AL, AZ, CA, CO, DC, FL, GA,  HI, IA, IL, IN,  KS, LA, MD, MI, MO, MS, NC, NV, OH, OR, PA, SC, SD, TN, TX, VA, WA				AL, AZ, CA, FL, IN, PA, TX				AL, IN, MI, TN, VA
Land
Initial Investment						$ 139,794				$ 20,532				$ 1,828				$ 162,154		$ 25,171		$ 0		$ 187,325
Cost Capitalized Subsequent to Acquisition						3,333				150				73				3,556		0		0		3,556
Total	187,046	[1]				143,127				20,682				1,901				165,710		25,171		0		190,881
Buildings, Improvements, Lease Intangibles and CIP
Initial Investment						1,980,035				343,136				36,323				2,359,494		0		0		2,359,494
Cost Capitalized Subsequent to Acquisition						259,754				4,326				7,530				271,610		0		0		271,610
Total						2,239,789				347,462				43,853				2,631,104		0		0		2,631,104
Personal Property	19,100					3,639				0				636				4,275		0		15,037		19,312
Gross real estate asset, Total	2,841,297		2,841,453	2,614,557	2,250,879	2,386,555	[2],[3],[4]			368,144	[2],[3],[4]			46,390	[2],[3],[4]			2,801,089	[2],[3],[4]	25,171	[2],[3],[4]	15,037	[2],[3],[4]	2,841,297	[2],[3],[4]
Accumulated depreciation	586,725					474,635	[3],[4],[5]			86,213	[3],[4],[5]			23,096	[3],[4],[5]			583,944	[3],[4],[5]	64	[3],[4],[5]	9,020	[3],[4],[5]	593,028	[3],[4],[5]
Encumbrances						$ 220,906	[6]			$ 0	[6]			$ 1,581	[6]			$ 222,487	[6]	$ 0	[6]	$ 0	[6]	$ 222,487	[6]
Date Acquired								Jan. 01, 1993	Dec. 31, 2012			Jan. 01, 1994	Dec. 31, 2012			Jan. 01, 1993	Dec. 31, 2011
Date Constructed								Jan. 01, 1905	Dec. 31, 2012			Jan. 01, 1983	Dec. 31, 2012			Jan. 01, 1906	Dec. 31, 1995

[1] Includes hand held for development.

[2] Total assets as of December 31, 2012 have an estimated aggregate total cost of $2.8 billion for federal income tax purposes.

[3] A reconciliation of Total Property and Accumulated Depreciation for the twelve months ended December 31, 2012, 2011 and 2010 follows:

[4] Depreciation is provided for on a straight-line basis on buildings and improvements over 3.3 to 39.0 years, lease intangibles over 2.0 to 93.1 years, personal property over 3.0 to 15.8 years, and land improvements over 15.0 to 38.1 years.

[5] Includes one asset held for sale as of December 31, 2012 of approximately $9.6 million (gross) and accumulated depreciation of $6.3 million, 15 assets held for sale as of December 31, 2011 of approximately $52.8 million (gross) and accumulated depreciation of $24.6 million; and 11 assets held for sale as of December 31, 2010 of $43.0 million (gross) and accumulated depreciation of $19.5 million.

[6] Includes unaccreted discounts, net of premiums totaling 2.8 million as of December 31, 2012.