Summary of Significant Accounting Policies - Narrative (Details) (USD $)	3 Months Ended			12 Months Ended						12 Months Ended						12 Months Ended			12 Months Ended			1 Months Ended	12 Months Ended			12 Months Ended
	Dec. 31, 2013 Property mortgage_note_receivable sqft ConstructionLoan state		Sep. 30, 2013 Property	Dec. 31, 2013 employee Property mortgage_note_receivable sqft ConstructionLoan state		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013 Mortgage Notes Receivable [Member] mortgage_note_receivable property	Dec. 31, 2012 Mortgage Notes Receivable [Member]	Dec. 31, 2013 Mortgage Notes Receivable [Member] Maximum [Member]	Dec. 31, 2012 Mortgage Notes Receivable [Member] Maximum [Member]	Dec. 31, 2013 Mortgage Notes Receivable [Member] Minimum [Member]	Dec. 31, 2012 Mortgage Notes Receivable [Member] Minimum [Member]	Dec. 31, 2013 At Market Lease Intangibles [Member]	Dec. 31, 2012 At Market Lease Intangibles [Member]	Dec. 31, 2013 Restatement Adjustment [Member]	Dec. 31, 2013 Variable Interest Entity, Not Primary Beneficiary [Member] mortgage_loan	Dec. 31, 2012 Variable Interest Entity, Not Primary Beneficiary [Member] mortgage_loan	Dec. 31, 2013 Texas [Member]	Jan. 31, 2014 Mortgage Note Financing [Member] Iowa [Member] Subsequent Event [Member]	Dec. 31, 2013 Texas [Member]	Dec. 31, 2013 Real Estate [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Property	Dec. 31, 2013 Employee Stock Purchase Plan [Member]	Dec. 31, 2012 Employee Stock Purchase Plan [Member]	Dec. 31, 2011 Employee Stock Purchase Plan [Member]
Business Overview [Abstract]
Gross investment, amount, total	$ 3,200,000,000			$ 3,200,000,000
Real estate properties and mortgages	202			202						4
Number of owned real estate properties	198			198
Number of states that the Company owns real estate in	28			28
Square footage of owned real estate properties	13,900,000			13,900,000
Approximate square feet for which Nationwide property management services provided by company	10,300,000			10,300,000
Principles of Consolidation [Abstract]
Number of construction mortgages loans																			1	2
Aggregate amount of construction mortgage loans	125,547,000			125,547,000															80,000,000	118,400,000
Assets of consolidated partnership																								17,700,000
Capital Contribution Proceeds From Minority Shareholders																							1,800,000
Investments in unconsolidated joint venture						1,300,000
Gain on sale of cost method investment in real estate				1,492,000		0		0
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners																					40.00%
Reclassifications [Abstract]
Personal Property	(9,267,000)			(9,267,000)		(8,739,000)												4,300,000
Real Estate Properties [Abstract]
Total real estate properties	3,067,187,000			3,067,187,000		2,821,323,000
Elimination of real estate lease intangibles against accumulated depreciation																4,400,000	2,500,000
Elimination of personal property and equipment against respective accumulated depreciation balances						200,000
Maximum period up to which interest capitalize on properties in stabilization				1 year
Land Held for Development [Abstract]
Land held for development	17,100,000			17,100,000		25,200,000
Fair Value Measurements [Abstract]
Number of impaired properties sold				1
Other asset impairment charges				3,300,000
Impairment charges on Assets classified as held for sale				6,600,000
Number of real estate properties classified as held for sale																									1
Number of Properties Reclassified to Held For Sale			4
Number of Held for Sale Properties Sold	2
Mortgage Notes and Notes Receivable [Abstract]
Number of mortgage notes receivable outstanding	2			2						4
Mortgage notes receivable outstanding										125,500,000	162,200,000
Weighted average maturity period for Mortgage notes receivable										0 years 4 months 16 days	1 year 0 months 15 days
Weighted average interest rate for Mortgage notes receivable												7.72%	7.70%	5.00%	6.75%
Mortgage notes receivable	125,547,000	[1]		125,547,000	[1]	162,191,000	[1]	97,381,000	36,599,000													41,500,000
Mortgage Loan on Real Estate Exit Fee																						1,500,000
Goodwill and Intangible Assets [Abstract]
Goodwill	3,500,000			3,500,000		3,500,000
Goodwill, Impairment Loss				0		0
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
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
General and Administrative Expense				23,729,000		20,905,000		20,988,000																		300,000	400,000	200,000
Revenue Recognition [Abstract]
Deferred revenue	36,300,000			36,300,000		34,800,000
Deferred revenue, tenant reimbursements	21,900,000			21,900,000		22,500,000
Rental Income [Abstract]
Operating expense recoveries included in income from continuing operations				40,900,000		33,500,000		30,700,000
Additional rental income, net of reserves included in income from continuing operations				$ 700,000		$ 700,000		$ 900,000
Mortgage Interest income [Abstract]
Number of Mortgage notes receivable outstanding with fixed interest rate	4			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			5
Federal Income Taxes [Abstract]
Percentage of distribution of taxable income for qualify as REIT				90.00%

[1] Level 2 - Fair value based on quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-driven valuations in which significant inputs and significant value drivers are observable in active markets.