Acquisitions, Dispositions and Mortgage Repayments (Details Textual) (USD $)	3 Months Ended			12 Months Ended							12 Months Ended					12 Months Ended							12 Months Ended								12 Months Ended								12 Months Ended								12 Months Ended					12 Months Ended			1 Months Ended	3 Months Ended		12 Months Ended									12 Months Ended						12 Months Ended				12 Months Ended				12 Months Ended					12 Months Ended										12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010	Dec. 31, 2012 sqft	Dec. 31, 2011 sqft		Dec. 31, 2010	Jan. 31, 2013 Inpatient Rehabilitation Hospital Potential Disposition July 2013 [Member] Subsequent Event [Member] hospital	Dec. 31, 2012 Inpatient Rehabilitation Hospital Potential Disposition July 2013 [Member] Subsequent Event [Member]	Dec. 31, 2012 Inpatient Rehabilitation Hospital Potential Disposition September 2013 [Member] Subsequent Event [Member] hospital	Dec. 31, 2011 Florida [Member] Medical Office Buildings Disposed February 2011 [Member]	Jul. 15, 2013 Florida [Member] Inpatient Rehabilitation Hospital Potential Disposition July 2013 [Member] Subsequent Event [Member] hospital	Dec. 31, 2012 Florida [Member] Inpatient Rehabilitation Hospital Potential Disposition July 2013 [Member] Subsequent Event [Member]	Jul. 31, 2013 Alabama [Member] Inpatient Rehabilitation Hospital Potential Disposition July 2013 [Member] Subsequent Event [Member] hospital	Dec. 31, 2012 Alabama [Member] Inpatient Rehabilitation Hospital Potential Disposition July 2013 [Member] Subsequent Event [Member]	Dec. 31, 2012 Real estate dispositions [Member] sqft	Dec. 31, 2011 Real estate dispositions [Member] sqft	Dec. 31, 2012 Real estate dispositions [Member] Medical Office Buidlings Disposed January 2012 [Member] property	Dec. 31, 2012 Real estate dispositions [Member] Iowa [Member] Medical Office Buildings Disposed December 2012 [Member] property sqft		Dec. 31, 2012 Real estate dispositions [Member] Iowa [Member] Medical Office Buildings Disposed December 2012 [Member] Medical Office Building One [Member] sqft	Dec. 31, 2012 Real estate dispositions [Member] Iowa [Member] Medical Office Buildings Disposed December 2012 [Member] Medical Office Building Two [Member] sqft	Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buidlings Disposed January 2012 [Member] sqft		Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buildings Disposed March 2012 [Member] sqft		Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buidlings Disposed April 2012 [Member] property Building sqft		Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buidlings Disposed April 2012 [Member] Contingent Liability [Member]	Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buidlings Disposed April 2012 [Member] Closing Cost [Member]	Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buildings Disposed August 2012 [Member] sqft		Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buildings Disposed September 2012 [Member] sqft		Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buildings Disposed September 2012 [Member] Medical Office Building One [Member] sqft		Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buildings Disposed September 2012 [Member] Medical Office Building Two [Member] sqft		Dec. 31, 2012 Real estate dispositions [Member] Florida [Member] Medical Office Buildings Disposed December 2012 [Member] sqft	Dec. 31, 2011 Real estate dispositions [Member] Florida [Member] Medical Office Buildings Disposed February 2011 [Member] sqft	Dec. 31, 2011 Real estate dispositions [Member] Florida [Member] Medical Office Buildings Disposed August 2011 [Member] sqft	Dec. 31, 2011 Real estate dispositions [Member] Massachusetts [Member] Medical Office Buildings Disposed December 2011 [Member] sqft	Dec. 31, 2012 Real estate dispositions [Member] Texas [Member] Medical Office Buidlings Disposed January 2012 [Member] property sqft		Dec. 31, 2012 Real estate dispositions [Member] Texas [Member] Medical Office Buidlings Disposed January 2012 [Member] Medical Office Building One [Member] sqft	Dec. 31, 2012 Real estate dispositions [Member] Texas [Member] Medical Office Buidlings Disposed January 2012 [Member] Medical Office Building Two [Member] sqft	Dec. 31, 2012 Real estate dispositions [Member] Texas [Member] Medical Office Buildings Disposed March 2012 [Member] sqft		Dec. 31, 2012 Real estate dispositions [Member] Texas [Member] Medical Office Buildings Disposed August 2012 [Member] sqft	Dec. 31, 2012 Real estate dispositions [Member] Texas [Member] Medical Office Buildings Disposed August 2012 [Member] Closing Cost [Member]	Dec. 31, 2012 Real estate dispositions [Member] Texas [Member] Medical Office Buildings Disposed August 2012 [Member] Tenant Improvements [Member]	Dec. 31, 2011 Real estate dispositions [Member] Massachusetts One [Member] Medical Office Buildings Disposed December 2011 [Member] sqft	Dec. 31, 2012 Real estate dispositions [Member] Tennessee [Member] Medical Office Buidlings Disposed April 2012 [Member] sqft		Jan. 31, 2012 Deconsolidation of Vie [Member]	Mar. 31, 2012 Deconsolidation of Vie [Member]		Dec. 31, 2012 Deconsolidation of Vie [Member] sqft		Dec. 31, 2012 Mortgage note repayments [Member]	Dec. 31, 2011 Mortgage note repayments [Member] mortgage_note_receivable	Dec. 31, 2011 Mortgage note repayments [Member] Florida [Member] Mortgage Loan Receviable Due March 2016 [Member]	Dec. 31, 2012 Real estate acquisitions [Member] sqft mortgage_note_receivable		Dec. 31, 2011 Real estate acquisitions [Member] sqft		Dec. 31, 2010 Real estate acquisitions [Member] Bon Secours Health System [Member]	Dec. 31, 2012 Real estate acquisitions [Member] South Dakota [Member] sqft		Dec. 31, 2012 Real estate acquisitions [Member] North Carolina [Member] sqft property tenant		Feb. 10, 2012 Real estate acquisitions [Member] North Carolina [Member]	Dec. 31, 2011 Real estate acquisitions [Member] Pennsylvania [Member] transaction acre sqft		Dec. 31, 2012 Real estate acquisitions [Member] Pennsylvania [Member] acre sqft		Dec. 31, 2011 Real estate acquisitions [Member] Pennsylvania One [Member] acre sqft		Dec. 31, 2012 Real estate acquisitions [Member] Texas [Member] sqft mortgage_note_receivable		Dec. 31, 2012 Real estate acquisitions [Member] Texas One [Member] sqft		Dec. 31, 2012 Real estate acquisitions [Member] Tennessee [Member] sqft		Jan. 31, 2013 Real estate acquisitions [Member] Tennessee [Member] Subsequent Event [Member] sqft tenant	Dec. 31, 2012 Real estate acquisitions [Member] Washington [Member] sqft		Dec. 31, 2012 Real estate acquisitions [Member] Iowa [Member] sqft		Dec. 31, 2012 Real estate acquisitions [Member] Iowa [Member] 5.74% Mortgage Loan [Member]	Dec. 31, 2011 Real estate acquisitions [Member] Virginia [Member] sqft property state Bed hospital	Dec. 31, 2010 Real estate acquisitions [Member] Virginia [Member] state Bed hospital	Dec. 31, 2011 Purchase of noncontrolling interest [Member] Facility joint_venture sqft Building		Dec. 31, 2012 Purchase of noncontrolling interest [Member]	Dec. 31, 2011 Mortgage note financing [Member] 6.75% Mortgage Loan [Member] Facility Project hospital state	Dec. 31, 2011 Mortgage note financing [Member] 6.75% Mortgage Loan [Member] Minimum [Member]	Dec. 31, 2011 Mortgage note financing [Member] Iowa [Member] 7.7% Mortgage Loan [Member]	Dec. 31, 2012 Mortgage note financing [Member] Florida [Member] Mortgage Loan Receviable Due April 2015 [Member]	Dec. 31, 2011 Mortgage note financing [Member] Oklahoma [Member] 6.75% Mortgage Loan [Member] sqft	Dec. 31, 2011 Mortgage note financing [Member] Missouri [Member] 6.75% Mortgage Loan [Member] sqft	Dec. 31, 2011 Mortgage note financing [Member] Missouri [Member] 11.0% Mortgage Loan [Member]
Real Estate Additions During the Period [Abstract]
Square footage					548,209																																																										394,064		548,209			58,285		23,312									76,484		66,095		39,345		52,225	47,225		83,318			548,209
Cash consideration					$ 102,700,000	[1]																																																									$ 89,800,000	[2]	$ 101,400,000	[1]		$ 15,000,000	[2]	$ 6,400,000	[2]		$ 1,900,000	[1]	$ 1,100,000	[2]	$ 3,600,000	[1]	$ 800,000	[2]	$ 30,600,000	[2]	$ 11,000,000	[2]		$ 9,400,000	[2]	$ 15,500,000	[2]		$ 95,900,000		$ 1,300,000	[1]
Total aggregate purchase price					158,900,000																																																										104,600,000		153,800,000			15,000,000		6,400,000			1,900,000		1,100,000		3,600,000		10,700,000		30,600,000		11,000,000		16,200,000	9,400,000		20,400,000			148,300,000		5,100,000		5,100,000
Mortgage note financing																																																															(9,900,000)																(9,900,000)																			40,000,000				2,300,000
Mortgage notes payable assumed					52,400,000																																																										4,900,000		52,400,000																							4,900,000
Percentage of medical office building leased																																																																				100.00%											100.00%		100.00%				100.00%			100.00%										94.00%
Percentage of medical office building occupied																																																																						100.00%		93.00%											100.00%			89.00%
Number of tenants occupying building																																																																						2															4
Number of medical office buildings in health system																																																																						6
Acquired land related to currently owned building previous (in acres)																																																																											9.14
Lease expiration period																																																																				Jan. 01, 2022													Jan. 01, 2032		Jan. 01, 2025			Jan. 01, 2021		Jan. 01, 2020
Agreement to purchase no. of outpatient buildings																																																																																											7
Number of noncontrolling equity interests in consolidated joint ventures purchased																																																																																													2
Prepaid ground rent																																																																																											12,800,000
Percentage of outpatient buildings leased																																																																																											95.40%		100.00%
Percentage of total square feet of the portfolio leasing by the affiliates																																																																																											35.00%
Area covered under real estate owned in measurement unit																																																																						187,000
Revenue generated from health system based in Marriottsville, Maryland																																																																			2,800,000,000
Square footage, whole units																																																																																													369,000
Number of beds in health system																																																																																												2,938
Number of acute care hospitals in health system																																																																																												18				26
Company has expensed in project cost to date related to the acquisition of this portfolio																																																																																											1,300,000	300,000
Number of transactions in real estate acquisition																																																																									2
Acquired land related to currently owned building previously on ground lease																																																																									7.8				16.2
Noncontrolling interest					3,600,000																																																																																								3,600,000
Note receivable repayment					(3,500,000)																																																																																								(3,500,000)
Leased outpatient facilities																																																																																													9
Aggregate investment in leased outpatient facilities																																																																																													87,600,000
Number of medical office buildings under construction																																																																																													2
Aggregate budget to construct two medical office buildings and parking garage																																																																																													54,900,000
Fair value adjustments in mortgage notes payable					2,000,000																																																																																			300,000
Asset Dispositions [Abstract]
Square Footage					181,620											757,826	181,620		40,818	[3]	31,650	9,168	35,752	[4]	33,895	[4]	272,571	[5]			8,990	[4]	71,345	[3]	61,763	[3]	9,582	[3]	62,271	28,861	16,256	24,900	33,726	[3],[4],[6]	14,748	18,978	82,664	[4],[7]	80,740			75,842	18,476	[4]
Net Real Estate Investment					17,300,000											83,400,000	17,300,000		6,700,000	[3]			3,000,000	[4]	500,000	[4]	31,200,000	[5]			900,000	[4]	10,800,000	[3]					9,700,000	3,100,000	2,800,000	1,600,000	2,500,000	[3],[4],[6]			4,800,000	[4],[7]	12,000,000			6,300,000	800,000	[4]				38,200,000	[8]
Real Estate Other					1,100,000											2,800,000	1,100,000		100,000	[3]			200,000	[4]	0	[4]	1,300,000	[5]			0	[4]	400,000	[3]					0	0	0	0	0	[3],[4],[6]			100,000	[4],[7]	700,000			1,100,000	0	[4]				(3,400,000)	[8]
Number of properties included																											5
Number of properties sold																		2	2																								2
Sales Price				91,500,000	22,800,000											91,500,000	22,800,000		8,000,000	[3]			7,200,000	[4]	500,000	[4]	33,300,000	[5]			500,000	[4]	8,800,000	[3]					2,100,000	3,200,000	1,300,000	3,200,000	3,500,000	[3],[4],[6]			4,700,000	[4],[7]	21,400,000			11,400,000	900,000	[4]
Net Proceeds				74,817,000	19,572,000		34,512,000									74,800,000	19,600,000		8,000,000	[3]			5,700,000	[4]	500,000	[4]	28,700,000	[5]			500,000	[4]	8,700,000	[3]					2,000,000	400,000	1,200,000	3,200,000	400,000	[3],[4],[6]			0	[4],[7]	19,000,000			11,400,000	800,000	[4]				35,100,000	[8]	24,700,000	17,200,000
Seller financed mortgage notes receivable					2,700,000											11,200,000	2,700,000		0	[3]			0	[4]	0	[4]	3,700,000	[5]			0	[4]	0	[3]					0	2,700,000	0	0	3,000,000	[3],[4],[6]			4,500,000	[4],[7]	0			0	0	[4]						(24,700,000)		2,700,000
Number of properties sold with company financed mortgage notes																											2
Closing adjustments				5,500,000	500,000											5,500,000	500,000		0	[3]			1,500,000	[4]	0	[4]	900,000	[5]	600,000	300,000	0	[4]	100,000	[3]					100,000	100,000	100,000	0	100,000	[3],[4],[6]			200,000	[4],[7]	2,400,000	400,000	2,000,000	0	100,000	[4]
Gain/ (Impairment)											0					(200,000)	3,900,000		1,200,000	[3]			2,500,000	[4]	0	[4]	(100,000)	[5]			(400,000)	[4]	(2,500,000)	[3]					(7,700,000)		(1,600,000)	1,600,000	900,000	[3],[4],[6]			(400,000)	[4],[7]	6,300,000			4,000,000	0	[4]		300,000	[8]	300,000	[8]		1,400,000
Total dispositions and repayments Square Footage				871,428																																																						113,602	[8]
Number of mortgage notes receivable repaid																																																													2		5																1
Dispositions and repayments Mortgage Note Receivable				(13,500,000)																																																											14,800,000																9,900,000
Number of medical office disposed off campus																											4
Number of medical office disposed on campus																											1
Mortgage interest				9,186,000	6,973,000		2,377,000																																																	400,000		400,000
General and administrative	400,000	200,000	200,000	20,908,000	20,990,000		16,886,000																																																	100,000		100,000
Mortgage Note Acqusitions [Abstract]
Cash consideration																																																																																																40,500,000
Number of developing build to suit facilities																																																																																																2
Aggregate budget to begin funding the development of two build to suit facilities affiliated with Mercy Health																																																																																																202,600,000
Number of projects																																																																																																2
Medical office building area																																																																																																				200,000
Construction budget																																																																																																				91,200,000	111,400,000
Orthopedic surgical facility area																																																																																																					186,000
Contractual interest rates																																																														7.00%																												5.74%						6.75%		7.70%	7.50%			11.00%
Debt instrument, maturity date																																											Nov. 30, 2012				Apr. 30, 2012																																											Jan. 01, 2020								Jan. 31, 2014	Apr. 30, 2015			Oct. 31, 2011
Period of lease agreement																																																																																																14 years
Net worth of affiliates																																																																																																	2,000,000,000
Number of heart hospitals in healthcare system																																																																																																2
Area of health system																																																																																												7				7
Repayments of construction mortgage note receivable																																																							35,100,000
Number of lease properties, lessee purchase options exercised								2				1		1
Number of leased properties, lessee purchase options										2
Leased properties, purchase option, minimum purchase price										17,600,000			11,700,000		17,500,000
Net real estate investment				2,244,959,000	2,271,871,000				18,700,000	25,400,000
Leased properties, purchase option, lease base rent per quarter									1,000,000	1,300,000
Land held for development				$ 25,171,000	$ 25,176,000

[1] Cash Consideration excludes receivables acquired and liabilities assumed in the acquisition.

[2] Cash Consideration excludes receivables acquired and liabilities assumed in the acquisitions.

[3] Includes two properties.

[4] Previously included in assets held for sale.

[5] Includes five properties.

[6] Mortgage note was repaid in November 2012.

[7] Mortgage note was repaid in April 2012.

[8] “Other” includes construction liabilities transferred upon deconsolidation. “Gain” includes $0.4 million of net mortgage interest income recognized, partially offset by $0.1 million of general and administrative overhead expense that had been capitalized into the project that was reversed upon deconsolidation.