Property Investments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013 property	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of Company's investment
Number of owned real estate properties	198
Number of real estate investments	202
Land	$ 195,985
Buildings, Improvements and Lease Intangibles	2,861,935
Personal Property	9,267
Gross real estate asset, Total	3,084,166	2,830,931	2,831,732	2,605,516
Total real estate investments	3,192,734
Accumulated Depreciation	(642,320)	(586,920)	(536,682)	(500,406)
Mortgage Notes Receivable [Member]
Summary of Company's investment
Number of real estate investments	4
Land	0
Buildings, Improvements and Lease Intangibles	0
Personal Property	0
Gross real estate asset, Total	125,547
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	5,397
Gross real estate asset, Total	22,451
Accumulated Depreciation	(3,592)
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
Personal Property	0
Gross real estate asset, Total	17,054
Accumulated Depreciation	(89)
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	5,397
Gross real estate asset, Total	5,397
Accumulated Depreciation	(3,503)
Owned Property [Member]
Summary of Company's investment
Number of owned real estate properties	198
Land	195,985
Buildings, Improvements and Lease Intangibles	2,861,935
Personal Property	9,267
Gross real estate asset, Total	3,067,187
Accumulated Depreciation	(632,109)
Medical office/outpatient [Member]
Summary of Company's investment
Number of owned real estate properties	174
Land	153,644
Buildings, Improvements and Lease Intangibles	2,403,831
Personal Property	2,969
Gross real estate asset, Total	2,560,444
Accumulated Depreciation	(532,460)
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	100,615
Personal Property	184
Gross real estate asset, Total	118,229
Accumulated Depreciation	(48,656)
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	186,262
Personal Property	208
Gross real estate asset, Total	193,667
Accumulated Depreciation	(12,355)
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	140,336
Personal Property	0
Gross real estate asset, Total	144,227
Accumulated Depreciation	(17,166)
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	81,372
Personal Property	94
Gross real estate asset, Total	94,131
Accumulated Depreciation	(10,422)
Medical office/outpatient [Member] | Florida [Member]
Summary of Company's investment
Number of owned real estate properties	7
Land	5,292
Buildings, Improvements and Lease Intangibles	83,042
Personal Property	251
Gross real estate asset, Total	88,585
Accumulated Depreciation	(40,185)
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	119,815
Personal Property	61
Gross real estate asset, Total	128,203
Accumulated Depreciation	(14,317)
Medical office/outpatient [Member] | North Carolina [Member]
Summary of Company's investment
Number of owned real estate properties	15
Land	4,200
Buildings, Improvements and Lease Intangibles	150,549
Personal Property	95
Gross real estate asset, Total	154,844
Accumulated Depreciation	(28,564)
Medical office/outpatient [Member] | Tennessee [Member]
Summary of Company's investment
Number of owned real estate properties	16
Land	11,419
Buildings, Improvements and Lease Intangibles	181,544
Personal Property	171
Gross real estate asset, Total	193,134
Accumulated Depreciation	(54,096)
Medical office/outpatient [Member] | Texas [Member]
Summary of Company's investment
Number of owned real estate properties	45
Land	47,784
Buildings, Improvements and Lease Intangibles	632,582
Personal Property	1,285
Gross real estate asset, Total	681,651
Accumulated Depreciation	(142,821)
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	189,119
Personal Property	158
Gross real estate asset, Total	191,728
Accumulated Depreciation	(35,633)
Medical office/outpatient [Member] | Washington [Member]
Summary of Company's investment
Number of owned real estate properties	7
Land	8,974
Buildings, Improvements and Lease Intangibles	176,921
Personal Property	135
Gross real estate asset, Total	186,030
Accumulated Depreciation	(16,392)
Medical office/outpatient [Member] | Other (17 states) [Member]
Summary of Company's investment
Number of owned real estate properties	39
Land	24,014
Buildings, Improvements and Lease Intangibles	361,674
Personal Property	327
Gross real estate asset, Total	386,015
Accumulated Depreciation	(111,853)
Inpatient [Member]
Summary of Company's investment
Number of owned real estate properties	14
Land	23,386
Buildings, Improvements and Lease Intangibles	413,933
Personal Property	265
Gross real estate asset, Total	437,584
Accumulated Depreciation	(71,563)
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
Gross real estate asset, Total	12,688
Accumulated Depreciation	(6,305)
Inpatient [Member] | Colorado [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	623
Buildings, Improvements and Lease Intangibles	6,496
Personal Property	0
Gross real estate asset, Total	7,119
Accumulated Depreciation	0
Inpatient [Member] | Indiana [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	1,071
Buildings, Improvements and Lease Intangibles	42,334
Personal Property	0
Gross real estate asset, Total	43,405
Accumulated Depreciation	(8,141)
Inpatient [Member] | Missouri [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	1,989
Buildings, Improvements and Lease Intangibles	107,487
Personal Property	0
Gross real estate asset, Total	109,476
Accumulated Depreciation	(679)
Inpatient [Member] | Texas [Member]
Summary of Company's investment
Number of owned real estate properties	5
Land	9,507
Buildings, Improvements and Lease Intangibles	157,923
Personal Property	265
Gross real estate asset, Total	167,695
Accumulated Depreciation	(19,151)
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
Gross real estate asset, Total	81,189
Accumulated Depreciation	(35,804)
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
Gross real estate asset, Total	16,012
Accumulated Depreciation	(1,483)
Other [Member]
Summary of Company's investment
Number of owned real estate properties	10
Land	1,901
Buildings, Improvements and Lease Intangibles	44,171
Personal Property	636
Gross real estate asset, Total	46,708
Accumulated Depreciation	(24,494)
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
Gross real estate asset, Total	3,790
Accumulated Depreciation	(2,362)
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
Gross real estate asset, Total	13,104
Accumulated Depreciation	(7,982)
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
Gross real estate asset, Total	7,874
Accumulated Depreciation	(2,097)
Other [Member] | Virginia [Member]
Summary of Company's investment
Number of owned real estate properties	2
Land	1,178
Buildings, Improvements and Lease Intangibles	10,685
Personal Property	5
Gross real estate asset, Total	11,868
Accumulated Depreciation	(5,790)
Other [Member] | Alabama [Member]
Summary of Company's investment
Number of owned real estate properties	1
Land	181
Buildings, Improvements and Lease Intangibles	9,883
Personal Property	8
Gross real estate asset, Total	10,072
Accumulated Depreciation	$ (6,263)