Borrowings Under Credit Facilities and Related Items (Details Textual)	9 Months Ended
	Sep. 30, 2015 USD ($) Number		Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)
Line Of Credit Facility [Line Items]
Unsecured line of credit arrangement	$ 2,500,000,000
Additional unsecured line of credit arrangement	$ 1,000,000,000
Number of banks in consortium | Number	28
Available to borrow in alternate currencies	$ 500,000,000
Agent bank's prime rate of interest	1.119%
Interest Rate margin	0.925%
Annual facility fee for each bank based on commitment amount	0.15%
Debt instrument maturity date	Oct. 31, 2018
Balance outstanding at quarter end	$ 490,000,000	[1]	$ 0	$ 0
Term Loan Interest Rate Margin	1.169%
HCN Term Loan	$ 500,000,000
HCN Canadian Denomiated Term Loan	250,000,000
Accordion Feature [Member]
Line Of Credit Facility [Line Items]
HCN Canadian Denomiated Term Loan	250,000,000
Financial Stand by Letter Of Credit [Member]
Line Of Credit Facility [Line Items]
Balance outstanding at quarter end	$ 58,484,000

[1] (1) As of September 30, 2015, letters of credit in the aggregate amount of $58,484,000 have been issued, which reduces the borrowing capacity on the primary unsecured revolving credit facility.