Summary of Significant Accounting Policies (Details Textual) (USD $)	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2011	Mar. 31, 2011	Mar. 31, 2009	Dec. 31, 2011 Building Employee MortgageLoan sqft Property JointVenture State Facility	Dec. 31, 2010 Property	Dec. 31, 2009	Dec. 31, 2008
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Notes receivable				$ 300,000	$ 3,800,000
Summary of Significant Accounting Policies (Textual) [Abstract]
Gross investment, amount, total				2,900,000,000
Real estate properties and mortgages				209
Number of states that the Company owns real estate in, whole units				28
Number of owned real estate properties				201
Square footage of owned real estate properties				13,700,000
Number of investments, whole units				1
Number of facility types				3
Approximate square feet for which Nationwide property management services provided by company				10,300,000
Number of construction mortgages loans				2
Number of consolidated joint ventures with same joint venture partner				2
Mortgage receivable/payable eliminated				34,900,000
Construction in progress asset including accrued invoices				38,000,000
Number property reclassified from discontinued operations to continuing operations				1
Percentage of distribution of taxable income for qualify as REIT				90.00%
Number of employees covered by the Company's pension plan				3
Maximum annual benefits payable under the executive retirement plan				896,000,000
Defined Benefit Plan, Measurement Date				December,31
Benefits paid				(48,000)	(2,666,000)
Elimination of personal property and equipment against respective accumulated depreciation balances				1,100,000
Gross real estate asset, Total				2,887,265,000	2,614,557,000	2,250,879,000	2,120,853,000
Land held for development				25,200,000	20,800,000
Number of Medical office buildings sold				2
Number of real estate properties classified as held for sale				5
Number of mortgage notes receivable outstanding with variable interest rates				2
Other Asset Impairment Charges				1,700,000
Impairment charges on Assets classified as held for sale				5,000,000
Weighted average maturity period of assets in the fund				3 months
Investments in mortgage notes or notes receivable				0	0
Non-accrual status mortgage notes or notes receivable				0
Maturity Date Range Start				2013	2011
Maturity Date Range End				2015	2016
Goodwill				3,500,000	3,500,000
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
General and administrative	200,000	200,000	300,000	20,991,000	16,891,000	22,467,000
Deferred Revenue				24,300,000	17,300,000
Operating expense recoveries included in income from continuing operations				31,800,000	23,000,000	20,800,000
Additional rental income, net of reserves included in income from continuing operations				1,200,000	2,300,000	2,500,000
Number of Mortgage notes receivable outstanding with fixed interest rate				5
Income related to properties sold or held for sale included in discontinued operations				2,900,000	6,200,000	27,900,000
Number of properties included in assets held for sale				15	11
Number of owned real estate properties to which property operating agreements between company and sponsoring health system is applicable				6
Variable Interest Entity, Not Primary Beneficiary [Member]
Mortgage Loans on Real Estate [Line Items]
Aggregate amount of construction mortgage loans				40,500,000
Mortgage Notes and Notes Receivable [Member]
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Number of mortgage notes receivable outstanding				7	7
Mortgage notes receivable outstanding				97,400,000	36,600,000
Weighted average maturity period for Mortgage notes receivable				2.1	3.9
Notes receivable				300,000	3,800,000
Allowance of reserves related to mortgage and note receivable				100,000	0
Maximum [Member]
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Interest rate on the notes receivable				13.50%	11.60%
Maximum [Member] | Mortgage Notes and Notes Receivable [Member]
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Weighted average interest rate for Mortgage notes receivable				11.00%	11.00%
Minimum [Member]
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Interest rate on the notes receivable				8.00%	8.00%
Minimum [Member] | Mortgage Notes and Notes Receivable [Member]
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Weighted average interest rate for Mortgage notes receivable				6.75%	6.50%
Leases, Acquired-in-Place [Member]
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Elimination of real estate lease intangibles against accumulated depreciation				$ 40,000,000