Schedule III - Real Estate and Accumulated Depreciation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 Property		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of real estate properties
Number of Properties	198
Buildings, Improvements, Lease Intangibles and CIP
Gross real estate asset, Total	$ 3,271,536		$ 3,084,166	$ 2,830,931	$ 2,831,732
Accumulated depreciation	705,135		642,320	586,920	536,682
Medical office/outpatient [Member]
Summary of real estate properties
Number of Properties	175
State	AL, AZ, CA, CO, DC, FL, GA,  HI, IA, IL, IN,  KS, LA, MD, MI, MN, MO, MS, NC, NV, OH, OK, OR, SC, SD, TN, TX, VA, WA
Land
Initial Investment	155,470
Cost Capitalized Subsequent to Acquisition	2,725
Total	158,195
Buildings, Improvements, Lease Intangibles and CIP
Initial Investment	2,200,146
Cost Capitalized Subsequent to Acquisition	356,836
Total	2,556,982
Personal Property	3,507
Gross real estate asset, Total	2,718,684	[1],[2]
Accumulated depreciation	589,686	[2],[3]
Encumbrances	171,796	[4]
Medical office/outpatient [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP
Date Acquired	Jan. 01, 1993
Date Constructed	Jan. 01, 1905
Medical office/outpatient [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP
Date Acquired	Dec. 31, 2012
Date Constructed	Dec. 31, 2012
Inpatient [Member]
Summary of real estate properties
Number of Properties	14
State	AZ, CA, CO, IN, MO, PA, TX
Land
Initial Investment	23,236
Cost Capitalized Subsequent to Acquisition	150
Total	23,386
Buildings, Improvements, Lease Intangibles and CIP
Initial Investment	406,108
Cost Capitalized Subsequent to Acquisition	14,161
Total	420,269
Personal Property	265
Gross real estate asset, Total	443,920	[1],[2]
Accumulated depreciation	84,285	[2],[3]
Encumbrances	0	[4]
Inpatient [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP
Date Acquired	Jan. 01, 1994
Date Constructed	Jan. 01, 1983
Inpatient [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP
Date Acquired	Dec. 31, 2012
Date Constructed	Dec. 31, 2012
Other [Member]
Summary of real estate properties
Number of Properties	11
State	AL, IA, IN, MI TN, VA
Land
Initial Investment	1,828
Cost Capitalized Subsequent to Acquisition	73
Total	1,901
Buildings, Improvements, Lease Intangibles and CIP
Initial Investment	76,014
Cost Capitalized Subsequent to Acquisition	7,808
Total	83,822
Personal Property	679
Gross real estate asset, Total	86,402	[1],[2]
Accumulated depreciation	27,330	[2],[3]
Encumbrances	1,471	[4]
Other [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP
Date Acquired	Jan. 01, 1993
Date Constructed	Jan. 01, 1906
Other [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP
Date Acquired	Dec. 31, 2011
Date Constructed	Dec. 31, 1995
Real Estate [Member]
Summary of real estate properties
Number of Properties	200
Land
Initial Investment	180,534
Cost Capitalized Subsequent to Acquisition	2,948
Total	183,482
Buildings, Improvements, Lease Intangibles and CIP
Initial Investment	2,682,268
Cost Capitalized Subsequent to Acquisition	378,805
Total	3,061,073
Personal Property	4,451
Gross real estate asset, Total	3,249,006	[1],[2]
Accumulated depreciation	701,301	[2],[3]
Encumbrances	173,267	[4]
Land Held for Development [Member]
Summary of real estate properties
Number of Properties	0
Land
Initial Investment	17,054
Cost Capitalized Subsequent to Acquisition	0
Total	17,054
Buildings, Improvements, Lease Intangibles and CIP
Initial Investment	0
Cost Capitalized Subsequent to Acquisition	0
Total	0
Personal Property	0
Gross real estate asset, Total	17,054	[1],[2]
Accumulated depreciation	115	[2],[3]
Encumbrances	0	[4]
Corporate Property [Member]
Summary of real estate properties
Number of Properties	0
Land
Initial Investment	0
Cost Capitalized Subsequent to Acquisition	0
Total	0
Buildings, Improvements, Lease Intangibles and CIP
Initial Investment	0
Cost Capitalized Subsequent to Acquisition	0
Total	0
Personal Property	5,476
Gross real estate asset, Total	5,476	[1],[2]
Accumulated depreciation	3,719	[2],[3]
Encumbrances	0	[4]
Owned Property [Member]
Summary of real estate properties
Number of Properties	200
Land
Initial Investment	197,588
Cost Capitalized Subsequent to Acquisition	2,948
Total	200,536
Buildings, Improvements, Lease Intangibles and CIP
Initial Investment	2,682,268
Cost Capitalized Subsequent to Acquisition	378,805
Total	3,061,073
Personal Property	9,927
Gross real estate asset, Total	3,271,536	[1],[2]
Accumulated depreciation	705,135	[2],[3]
Encumbrances	$ 173,267	[4]

[1] Total assets as of December 31, 2014 have an estimated aggregate total cost of $3.3 billion for federal income tax purposes.

[2] Depreciation is provided for on a straight-line basis on buildings and improvements over 3.3 to 39.0 years, lease intangibles over 1.0 to 93.1 years, personal property over 1.9 to 15.8 years, and land improvements over 15.0 to 38.1 years.

[3] Includes two assets held for sale as of December 31, 2014 of approximately $13.3 million (gross) and accumulated depreciation of $4.5 million, three asset held for sale as of December 31, 2013 of approximately $17.0 million (gross) and accumulated depreciation of $10.2 million; and one assets held for sale as of December 31, 2012 of $9.6 million (gross) and accumulated depreciation of $6.3 million.

[4] Includes unamortized premium of $3.2 million and unaccreted discount of $2.5 million as of December 31, 2014.