Borrowings Under Credit Facilities and Related Items (Details Textual) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) properties		Dec. 31, 2015 USD ($)	Mar. 31, 2015 USD ($)	[1]
Line Of Credit Facility [Line Items]
Unsecured line of credit arrangement	$ 2,500,000
Number of banks in consortium | properties	28
Available to borrow in alternate currencies	$ 500,000
Agent bank's prime rate of interest	1.36%
Annual facility fee for each bank based on commitment amount	0.15%
Debt instrument maturity date	Oct. 31, 2018
Term Loan Interest Rate Margin	0.925%
HCN Term Loan	$ 500,000
HCN Canadian Denomiated Term Loan	250,000
Line Of Credit	645,000	[1]	$ 835,000	$ 410,000
Accordion Feature [Member]
Line Of Credit Facility [Line Items]
HCN Term Loan	1,000,000
HCN Canadian Denomiated Term Loan	$ 250,000

[1] (1) As of March 31, 2016, letters of credit in the aggregate amount of $48,930,000 have been issued, which reduces the borrowing capacity on the unsecured revolving credit facility.