Summary of Significant Accounting Policies (Details Textual) (USD $)	3 Months Ended			12 Months Ended					12 Months Ended						12 Months Ended						12 Months Ended										1 Months Ended	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010	Dec. 31, 2012 property employee Building joint_venture state sqft mortgage_note_receivable		Dec. 31, 2011 joint_venture	Dec. 31, 2010 joint_venture	Dec. 31, 2009	Dec. 31, 2012 Mortgage Notes Receivable [Member] property mortgage_note_receivable	Dec. 31, 2011 Mortgage Notes Receivable [Member] mortgage_note_receivable	Dec. 31, 2012 Mortgage Notes Receivable [Member] Maximum [Member]	Dec. 31, 2011 Mortgage Notes Receivable [Member] Maximum [Member]	Dec. 31, 2012 Mortgage Notes Receivable [Member] Minimum [Member]	Dec. 31, 2011 Mortgage Notes Receivable [Member] Minimum [Member]	Dec. 31, 2012 Notes Receivable [Member] note_receivable	Dec. 31, 2011 Notes Receivable [Member]	Dec. 31, 2012 Notes Receivable [Member] Maximum [Member]	Dec. 31, 2011 Notes Receivable [Member] Maximum [Member]	Dec. 31, 2012 Notes Receivable [Member] Minimum [Member]	Dec. 31, 2011 Notes Receivable [Member] Minimum [Member]	Dec. 31, 2012 Leases, Acquired-in-Place [Member]	Dec. 31, 2011 Leases, Acquired-in-Place [Member]	Dec. 31, 2011 Acquisitions of Real Estate [Member]	Dec. 31, 2010 Acquisitions of Real Estate [Member]	Dec. 31, 2011 Debt Issuance and Assumption Costs [Member]	Dec. 31, 2010 Debt Issuance and Assumption Costs [Member]	Dec. 31, 2011 Scenario, Previously Reported [Member] Other assets [Member]	Dec. 31, 2010 Scenario, Previously Reported [Member] Other assets [Member]	Dec. 31, 2012 Variable Interest Entity, Not Primary Beneficiary [Member] mortgage_loan	Dec. 31, 2011 Variable Interest Entity, Not Primary Beneficiary [Member]	Jan. 31, 2012 Deconsolidation of Vie [Member]	Mar. 31, 2012 Deconsolidation of Vie [Member]		Dec. 31, 2012 Deconsolidation of Vie [Member]
Business Overview [Abstract]
Gross investment, amount, total				$ 3,000,000,000
Real estate properties and mortgages				207					4
Number of owned real estate properties				202
Number of states that the Company owns real estate in				28
Square footage of owned real estate properties				13,600,000
Approximate square feet for which Nationwide property management services provided by company				10,100,000
Principles of Consolidation [Abstract]
Repayments of construction mortgage note receivable																															35,100,000
Mortgage Interest				9,186,000		6,973,000	2,377,000																									400,000		400,000
Deconsolidated VIE, net gain																																300,000	[1]	300,000	[1]
Number of construction mortgages loans																													2
Aggregate amount of construction mortgage loans				162,191,000	[2]																								118,400,000	40,500,000
Number of investments, whole units				1		0	0
Investments in unconsolidated joint venture				1,300,000		0	0
General and administrative	400,000	200,000	200,000	20,908,000		20,990,000	16,886,000																									100,000		100,000
Reclassifications [Abstract]
Number of properties reclassified from discontinued operations to continuing operations				6
Reclassifications on prior period amounts in statement of cash flows																							2,100,000	6,700,000	700,000	200,000	2,800,000	6,900,000
Real Estate Properties [Abstract]
Gross real estate asset, Total				2,841,297,000		2,841,453,000	2,614,557,000	2,250,879,000	162,191,000
Elimination of real estate lease intangibles against accumulated depreciation																					2,500,000	40,000,000
Elimination of personal property and equipment against respective accumulated depreciation balances				200,000		1,100,000
Maximum period up to which interest capitalize on properties in stabilization				1 year
Land Held for Development [Abstract]
Land held for development				25,200,000		25,200,000
Fair Value Measurements [Abstract]
Number of medical office buildings sold				12
Other asset impairment charges				11,100,000
Impairment charges on Assets classified as held for sale				3,800,000
Number of real estate properites classifed as held for sale				1
Mortgage Notes and Notes Receivable [Abstract]
Number of mortgage notes receivable outstanding									4	7
Mortgage notes receivable outstanding									162,200,000	97,400,000
Weighted average maturity period for Mortgage notes receivable									1 year	2 years 1 month 6 days
Weighted average interest rate for Mortgage notes receivable											7.70%	11.00%	6.75%	6.75%
Notes receivable				100,000		300,000									100,000	300,000
Interest rate on the notes receivable																	11.62%	13.50%	3.30%	8.00%
Maturity date, start															Dec. 31, 2014	Dec. 31, 2013
Maturity date, end															Dec. 31, 2016	Dec. 31, 2015
Allowance of reserves related to mortgage and note receivable															100,000
Number of notes receivable with related allowance															1
Goodwill and Intangible Assets [Abstract]
Goodwill				3,500,000		3,500,000
Defined Benefit Pension Plans [Abstract]
Number of employees covered by the Company's pension plan				3
Defined Benefit Plan, Measurement Date				December 31
Maximum annual benefits payable under the executive retirement plan				896,000
Benefits paid				42,000		48,000
Incentive Plans [Abstract]
Discount on market price on the date of grant				85.00%
Discount on market price on the date of exercise				85.00%
Expiration date				27 months
Revenue Recognition [Abstract]
Deferred revenue				34,800,000		24,300,000
Deferred revenue, tenant reimbursements				22,500,000		8,100,000
Rental Income [Abstract]
Operating expense recoveries included in income from continuing operations				34,000,000		31,200,000	22,500,000
Additional rental income, net of reserves included in income from continuing operations				$ 700,000		$ 1,200,000	$ 2,300,000
Mortgage Interest income [Abstract]
Number of Mortgage notes receivable outstanding with fixed interest rate				4
Other Operating Income [Abstract]
Number of owned real estate properties to which property operating agreements between company and sponsoring health system is applicable				5
Federal Income Taxes [Abstract]
Percentage of distribution of taxable income for qualify as REIT				90.00%

[1] “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.

[2] A rollforward of Mortgage loans on real estate for the three years ended December 31, 2012 follows: