Schedule III - Real Estate and Accumulated Depreciation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) property Property	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Summary of real estate properties
Number of Properties | property	202
Buildings, Improvements, Lease Intangibles and CIP (1)
Gross real estate asset, Total	$ 3,633,993	$ 3,382,680	$ 3,271,536	$ 3,084,166
Accumulated depreciation	$ 843,816	$ 762,996	$ 705,135	$ 642,320
Medical office/outpatient [Member]
Summary of real estate properties
Number of Properties | Property	184
State	AL, AZ, CA, CO, DC, FL, GA,  HI, IA, IL, IN,  LA, MD, MI, MN, MO, MS, NC, NV, OH, OK, OR, SC, SD, TN, TX, VA, WA
Land (1)
Initial Investment	$ 182,231
Cost Capitalized Subsequent to Acquisition	2,397
Total	184,628
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	2,536,076
Cost Capitalized Subsequent to Acquisition	447,126
Total	2,983,202
Personal Property	3,810
Gross real estate asset, Total	3,171,640
Accumulated depreciation	738,029
Encumbrances	$ 114,269
Medical office/outpatient [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Jan. 01, 1993
Date Constructed	Jan. 01, 1905
Medical office/outpatient [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Dec. 31, 2016
Date Constructed	Dec. 31, 2015
Inpatient [Member]
Summary of real estate properties
Number of Properties | Property	10
State	CA, CO, MO, PA, TX
Land (1)
Initial Investment	$ 13,095
Cost Capitalized Subsequent to Acquisition	150
Total	13,245
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	316,354
Cost Capitalized Subsequent to Acquisition	14,187
Total	330,541
Personal Property	265
Gross real estate asset, Total	344,051
Accumulated depreciation	75,518
Encumbrances	$ 0
Inpatient [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Jan. 01, 1998
Date Constructed	Jan. 01, 1983
Inpatient [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Dec. 31, 2013
Date Constructed	Dec. 31, 2013
Other [Member]
Summary of real estate properties
Number of Properties | Property	10
State	IA, IN, MI, TN, TX, VA
Land (1)
Initial Investment	$ 3,088
Cost Capitalized Subsequent to Acquisition	73
Total	3,161
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	69,951
Cost Capitalized Subsequent to Acquisition	7,196
Total	77,147
Personal Property	633
Gross real estate asset, Total	80,941
Accumulated depreciation	25,936
Encumbrances	$ 1,348
Other [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Jan. 01, 1993
Date Constructed	Jan. 01, 1964
Other [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Dec. 31, 2015
Date Constructed	Dec. 31, 2015
Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	204
Land (1)
Initial Investment	$ 198,414
Cost Capitalized Subsequent to Acquisition	2,620
Total	201,034
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	2,922,381
Cost Capitalized Subsequent to Acquisition	468,509
Total	3,390,890
Personal Property	4,708
Gross real estate asset, Total	3,596,632
Accumulated depreciation	839,483
Encumbrances	$ 115,617
Land Held for Development [Member]
Summary of real estate properties
Number of Properties | Property	0
Land (1)
Initial Investment	$ 20,123
Cost Capitalized Subsequent to Acquisition	0
Total	20,123
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	0
Cost Capitalized Subsequent to Acquisition	0
Total	0
Personal Property	0
Gross real estate asset, Total	20,123
Accumulated depreciation	166
Encumbrances	0
Construction in Progress [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Total	11,655
Gross real estate asset, Total	$ 11,655
Corporate Property [Member]
Summary of real estate properties
Number of Properties | Property	0
Land (1)
Initial Investment	$ 0
Cost Capitalized Subsequent to Acquisition	0
Total	0
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	0
Cost Capitalized Subsequent to Acquisition	0
Total	0
Personal Property	5,583
Gross real estate asset, Total	5,583
Accumulated depreciation	4,167
Encumbrances	$ 0
Owned Property [Member]
Summary of real estate properties
Number of Properties | Property	204
Land (1)
Initial Investment	$ 218,537
Cost Capitalized Subsequent to Acquisition	2,620
Total	221,157
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	2,922,381
Cost Capitalized Subsequent to Acquisition	468,509
Total	3,402,545
Personal Property	10,291
Gross real estate asset, Total	3,633,993
Accumulated depreciation	843,816
Encumbrances	$ 115,617