Real Estate Properties - Schedule of MOB Acquisitions (Details) $ in Thousands		1 Months Ended						12 Months Ended
	Jan. 17, 2017 ft² property	Dec. 31, 2017 USD ($) ft² property	Nov. 30, 2017 ft² property	Oct. 31, 2016 ft² property	May 31, 2016 USD ($) ft² property	Feb. 29, 2016 ft² property	Jan. 31, 2015 USD ($) ft² living_unit	Dec. 31, 2017 USD ($) ft² property	Dec. 31, 2016 USD ($) ft² property	Dec. 31, 2015 USD ($) ft² property	Jul. 12, 2017 ft²
Real Estate [Line Items]
Acquired Real Estate Leases		$ 791,067						$ 791,067	$ 775,935
Acquired Real Estate Lease Obligations		$ (136,713)						(136,713)	(137,351)
Acquisitions funded by assumed debt								$ 0	$ 0	$ (181,433)
MOBs | Acquisitions
Real Estate [Line Items]
Number of Properties							23	6	3	23
Square Feet (000's) | ft²		630,000					2,170,000	630,000	390,000	2,170,000
Cash Paid plus Assumed Debt								$ 113,168	$ 86,432	$ 531,623
Acquired Real Estate Leases		$ 27,713						27,713	9,645	87,780
Acquired Real Estate Lease Obligations		$ (20)						(20)	(1,091)	(3,150)
Acquisitions funded by assumed debt							$ (29,955)	0	0	(29,955)
Premium on Assumed Debt								$ 0	$ 0	$ (1,073)
MOBs | Kansas | Acquisitions
Real Estate [Line Items]
Number of Properties | property	1							1
Square Feet (000's) | ft²	117,000	117,000						117,000
Cash Paid plus Assumed Debt								$ 15,106
Acquired Real Estate Leases		$ 6,338						6,338
Acquired Real Estate Lease Obligations		$ 0						0
Acquisitions funded by assumed debt								0
Premium on Assumed Debt								$ 0
MOBs | Maryland | Acquisitions
Real Estate [Line Items]
Number of Properties | property			1					1
Square Feet (000's) | ft²		59,000						59,000			59,000
Cash Paid plus Assumed Debt								$ 16,601
Acquired Real Estate Leases		$ 3,937						3,937
Acquired Real Estate Lease Obligations		$ 0						0
Acquisitions funded by assumed debt								0
Premium on Assumed Debt								$ 0
MOBs | 2 States | Acquisitions
Real Estate [Line Items]
Number of Properties | property								2
Square Feet (000's) | ft²		255,000						255,000
Cash Paid plus Assumed Debt								$ 38,794
Acquired Real Estate Leases		$ 7,016						7,016
Acquired Real Estate Lease Obligations		$ 0						0
Acquisitions funded by assumed debt								0
Premium on Assumed Debt								$ 0
MOBs | California | Acquisitions
Real Estate [Line Items]
Number of Properties | property			1					1
Square Feet (000's) | ft²		63,000	63,000					63,000
Cash Paid plus Assumed Debt								$ 26,823
Acquired Real Estate Leases		$ 5,436						5,436
Acquired Real Estate Lease Obligations		$ 0						0
Acquisitions funded by assumed debt								0
Premium on Assumed Debt								$ 0
MOBs | Virginia | Acquisitions
Real Estate [Line Items]
Number of Properties | property		1						1
Square Feet (000's) | ft²		136,000						136,000
Cash Paid plus Assumed Debt								$ 15,844
Acquired Real Estate Leases		$ 4,986						4,986
Acquired Real Estate Lease Obligations		$ (20)						(20)
Acquisitions funded by assumed debt								0
Premium on Assumed Debt								0
MOBs | Minnesota
Real Estate [Line Items]
Number of Properties | property						1
Square Feet (000's) | ft²						128,000
MOBs | Minnesota | Acquisitions
Real Estate [Line Items]
Number of Properties | property									1
Square Feet (000's) | ft²									128,000
Cash Paid plus Assumed Debt									$ 22,700
Acquired Real Estate Leases									5,053
Acquired Real Estate Lease Obligations									(1,091)
Acquisitions funded by assumed debt									0
Premium on Assumed Debt									$ 0
MOBs | Florida
Real Estate [Line Items]
Number of Properties | property					1
Square Feet (000's) | ft²					166,000
Cash Paid plus Assumed Debt					$ 45,000
MOBs | Florida | Acquisitions
Real Estate [Line Items]
Number of Properties | property									1
Square Feet (000's) | ft²									166,000
Cash Paid plus Assumed Debt									$ 45,232
Acquired Real Estate Leases									0
Acquired Real Estate Lease Obligations									0
Acquisitions funded by assumed debt									0
Premium on Assumed Debt									$ 0
MOBs | Ohio
Real Estate [Line Items]
Number of Properties | property				1
Square Feet (000's) | ft²				96,000
MOBs | Ohio | Acquisitions
Real Estate [Line Items]
Number of Properties | property									1
Square Feet (000's) | ft²									96,000
Cash Paid plus Assumed Debt									$ 18,500
Acquired Real Estate Leases									4,592
Acquired Real Estate Lease Obligations									0
Acquisitions funded by assumed debt									0
Premium on Assumed Debt									0
MOBs | 12 States | Acquisitions
Real Estate [Line Items]
Number of Properties | property										23
Square Feet (000's) | ft²										2,170,000
Cash Paid plus Assumed Debt										$ 531,623
Acquired Real Estate Leases										87,780
Acquired Real Estate Lease Obligations										(3,150)
Acquisitions funded by assumed debt										(29,955)
Premium on Assumed Debt										(1,073)
Land | MOBs | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								25,618	7,845	50,429
Land | MOBs | Kansas | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								1,522
Land | MOBs | Maryland | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								6,138
Land | MOBs | 2 States | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								6,738
Land | MOBs | California | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								7,957
Land | MOBs | Virginia | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								3,263
Land | MOBs | Minnesota | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired									4,028
Land | MOBs | Florida | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired									2,792
Land | MOBs | Ohio | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired									1,025
Land | MOBs | 12 States | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired										50,429
Buildings and Improvements | MOBs | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								59,857	70,033	397,637
Buildings and Improvements | MOBs | Kansas | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								7,246
Buildings and Improvements | MOBs | Maryland | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								6,526
Buildings and Improvements | MOBs | 2 States | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								25,040
Buildings and Improvements | MOBs | California | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								13,430
Buildings and Improvements | MOBs | Virginia | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired								$ 7,615
Buildings and Improvements | MOBs | Minnesota | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired									14,710
Buildings and Improvements | MOBs | Florida | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired									42,440
Buildings and Improvements | MOBs | Ohio | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired									$ 12,883
Buildings and Improvements | MOBs | 12 States | Acquisitions
Real Estate [Line Items]
Property plant and equipment acquired										$ 397,637