Property Investments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014 property	Dec. 31, 2013
Summary of Company's investment
Number of real estate investments	199
Number of owned real estate properties	198
Land	$ 200,114
Buildings, Improvements, and Lease Intangibles	3,048,251	2,861,935
Personal Property	9,914	9,267
Total real estate properties	3,258,279	3,067,187
Mortgage notes receivable	1,900
Accumulated Depreciation	(700,671)	(632,109)
Total real estate investments	3,260,179
Mortgage Notes Receivable [Member]
Summary of Company's investment
Number of real estate investments	1
Land	0
Buildings, Improvements, and Lease Intangibles	0
Personal Property	0
Mortgage notes receivable	1,900
Accumulated Depreciation	0
Land Held for Development and Corporate Property [Member]
Summary of Company's investment
Number of owned real estate properties	0
Land	17,054
Buildings, Improvements, and Lease Intangibles	0
Personal Property	5,476
Total real estate properties	22,530
Accumulated Depreciation	(3,834)
Land Held for Development [Member]
Summary of Company's investment
Number of owned real estate properties	0
Land	17,054
Buildings, Improvements, and Lease Intangibles	0
Personal Property	0
Total real estate properties	17,054
Accumulated Depreciation	(115)
Corporate Property [Member]
Summary of Company's investment
Number of owned real estate properties	0
Land	0
Buildings, Improvements, and Lease Intangibles	0
Personal Property	5,476
Total real estate properties	5,476
Accumulated Depreciation	(3,719)
Owned Property [Member]
Summary of Company's investment
Number of owned real estate properties	198
Land	200,114
Buildings, Improvements, and Lease Intangibles	3,048,251
Personal Property	9,914
Total real estate properties	3,258,279
Accumulated Depreciation	(700,671)
Medical office/outpatient [Member]
Summary of Company's investment
Number of owned real estate properties	173
Land	157,773
Buildings, Improvements, and Lease Intangibles	2,544,160
Personal Property	3,494
Total real estate properties	2,705,427
Accumulated Depreciation	(585,222)
Medical office/outpatient [Member] | California [Member]
Summary of Company's investment
Number of owned real estate properties	9
Land	17,430
Buildings, Improvements, and Lease Intangibles	104,983
Personal Property	195
Total real estate properties	122,608
Accumulated Depreciation	(53,254)
Medical office/outpatient [Member] | Colorado [Member]
Summary of Company's investment
Number of owned real estate properties	9
Land	7,197
Buildings, Improvements, and Lease Intangibles	188,593
Personal Property	208
Total real estate properties	195,998
Accumulated Depreciation	(18,338)
Medical office/outpatient [Member] | District of Columbia [Member]
Summary of Company's investment
Number of owned real estate properties	2
Land	0
Buildings, Improvements, and Lease Intangibles	30,729
Personal Property	0
Total real estate properties	30,729
Accumulated Depreciation	(8,992)
Medical office/outpatient [Member] | Indiana [Member]
Summary of Company's investment
Number of owned real estate properties	5
Land	3,891
Buildings, Improvements, and Lease Intangibles	140,749
Personal Property	0
Total real estate properties	144,640
Accumulated Depreciation	(22,575)
Medical office/outpatient [Member] | Missouri [Member]
Summary of Company's investment
Number of owned real estate properties	4
Land	4,668
Buildings, Improvements, and Lease Intangibles	32,574
Personal Property	7
Total real estate properties	37,249
Accumulated Depreciation	(16,998)
Medical office/outpatient [Member] | Michigan [Member]
Summary of Company's investment
Number of owned real estate properties	3
Land	5
Buildings, Improvements, and Lease Intangibles	23,158
Personal Property	33
Total real estate properties	23,196
Accumulated Depreciation	(7,644)
Medical office/outpatient [Member] | Iowa [Member]
Summary of Company's investment
Number of owned real estate properties	6
Land	12,665
Buildings, Improvements, and Lease Intangibles	81,424
Personal Property	94
Total real estate properties	94,183
Accumulated Depreciation	(13,346)
Medical office/outpatient [Member] | Illinois [Member]
Summary of Company's investment
Number of owned real estate properties	3
Land	6,142
Buildings, Improvements, and Lease Intangibles	49,194
Personal Property	143
Total real estate properties	55,479
Accumulated Depreciation	(11,100)
Medical office/outpatient [Member] | Florida [Member]
Summary of Company's investment
Number of owned real estate properties	8
Land	6,891
Buildings, Improvements, and Lease Intangibles	90,674
Personal Property	252
Total real estate properties	97,817
Accumulated Depreciation	(43,774)
Medical office/outpatient [Member] | Hawaii [Member]
Summary of Company's investment
Number of owned real estate properties	3
Land	8,327
Buildings, Improvements, and Lease Intangibles	121,022
Personal Property	68
Total real estate properties	129,417
Accumulated Depreciation	(17,726)
Medical office/outpatient [Member] | North Carolina [Member]
Summary of Company's investment
Number of owned real estate properties	16
Land	5,096
Buildings, Improvements, and Lease Intangibles	156,538
Personal Property	95
Total real estate properties	161,729
Accumulated Depreciation	(34,824)
Medical office/outpatient [Member] | Oklahoma [Member]
Summary of Company's investment
Number of owned real estate properties	2
Land	7,673
Buildings, Improvements, and Lease Intangibles	100,543
Personal Property	0
Total real estate properties	108,216
Accumulated Depreciation	(1,486)
Medical office/outpatient [Member] | Tennessee [Member]
Summary of Company's investment
Number of owned real estate properties	14
Land	10,353
Buildings, Improvements, and Lease Intangibles	183,414
Personal Property	255
Total real estate properties	194,022
Accumulated Depreciation	(58,932)
Medical office/outpatient [Member] | Texas [Member]
Summary of Company's investment
Number of owned real estate properties	43
Land	45,036
Buildings, Improvements, and Lease Intangibles	621,608
Personal Property	1,290
Total real estate properties	667,934
Accumulated Depreciation	(145,509)
Medical office/outpatient [Member] | Virginia [Member]
Summary of Company's investment
Number of owned real estate properties	13
Land	2,451
Buildings, Improvements, and Lease Intangibles	183,340
Personal Property	136
Total real estate properties	185,927
Accumulated Depreciation	(36,277)
Medical office/outpatient [Member] | Washington [Member]
Summary of Company's investment
Number of owned real estate properties	8
Land	8,974
Buildings, Improvements, and Lease Intangibles	201,227
Personal Property	186
Total real estate properties	210,387
Accumulated Depreciation	(22,784)
Medical office/outpatient [Member] | Arizona [Member]
Summary of Company's investment
Number of owned real estate properties	9
Land	3,726
Buildings, Improvements, and Lease Intangibles	78,398
Personal Property	441
Total real estate properties	82,565
Accumulated Depreciation	(22,521)
Medical office/outpatient [Member] | Other (17 states) [Member]
Summary of Company's investment
Number of owned real estate properties	16
Land	7,248
Buildings, Improvements, and Lease Intangibles	155,992
Personal Property	91
Total real estate properties	163,331
Accumulated Depreciation	(49,142)
Inpatient [Member]
Summary of Company's investment
Number of owned real estate properties	14
Land	23,386
Buildings, Improvements, and Lease Intangibles	420,269
Personal Property	265
Total real estate properties	443,920
Accumulated Depreciation	(84,285)
Inpatient [Member] | California [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	0
Buildings, Improvements, and Lease Intangibles	12,688
Personal Property	0
Total real estate properties	12,688
Accumulated Depreciation	(6,630)
Inpatient [Member] | Colorado [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	623
Buildings, Improvements, and Lease Intangibles	10,788
Personal Property	0
Total real estate properties	11,411
Accumulated Depreciation	(362)
Inpatient [Member] | Indiana [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	1,071
Buildings, Improvements, and Lease Intangibles	42,335
Personal Property	0
Total real estate properties	43,406
Accumulated Depreciation	(9,227)
Inpatient [Member] | Missouri [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	1,989
Buildings, Improvements, and Lease Intangibles	109,304
Personal Property	0
Total real estate properties	111,293
Accumulated Depreciation	(3,503)
Inpatient [Member] | Texas [Member]
Summary of Company's investment
Number of owned real estate properties	5
Land	9,507
Buildings, Improvements, and Lease Intangibles	158,149
Personal Property	265
Total real estate properties	167,921
Accumulated Depreciation	(24,558)
Inpatient [Member] | Pennsylvania [Member]
Summary of Company's investment
Number of owned real estate properties	4
Land	6,555
Buildings, Improvements, and Lease Intangibles	74,634
Personal Property	0
Total real estate properties	81,189
Accumulated Depreciation	(38,166)
Inpatient [Member] | Arizona [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	3,641
Buildings, Improvements, and Lease Intangibles	12,371
Personal Property	0
Total real estate properties	16,012
Accumulated Depreciation	(1,839)
Other [Member]
Summary of Company's investment
Number of owned real estate properties	11
Land	1,901
Buildings, Improvements, and Lease Intangibles	83,822
Personal Property	679
Total real estate properties	86,402
Accumulated Depreciation	(27,330)
Other [Member] | Indiana [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	96
Buildings, Improvements, and Lease Intangibles	3,662
Personal Property	32
Total real estate properties	3,790
Accumulated Depreciation	(2,477)
Other [Member] | Michigan [Member]
Summary of Company's investment
Number of owned real estate properties	5
Land	193
Buildings, Improvements, and Lease Intangibles	12,728
Personal Property	183
Total real estate properties	13,104
Accumulated Depreciation	(8,379)
Other [Member] | Iowa [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	0
Buildings, Improvements, and Lease Intangibles	40,263
Personal Property	0
Total real estate properties	40,263
Accumulated Depreciation	(1,536)
Other [Member] | Tennessee [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	253
Buildings, Improvements, and Lease Intangibles	7,213
Personal Property	408
Total real estate properties	7,874
Accumulated Depreciation	(2,279)
Other [Member] | Virginia [Member]
Summary of Company's investment
Number of owned real estate properties	2
Land	1,178
Buildings, Improvements, and Lease Intangibles	10,031
Personal Property	48
Total real estate properties	11,257
Accumulated Depreciation	(6,054)
Other [Member] | Alabama [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	181
Buildings, Improvements, and Lease Intangibles	9,925
Personal Property	8
Total real estate properties	10,114
Accumulated Depreciation	$ (6,605)