Borrowings Under Credit Facilities and Related Items (Details Textual) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) Number
Line Of Credit Facility [Line Items]
Unsecured line of credit arrangement	$ 3,000,000
Number of banks in consortium | Number	29
Available to borrow in alternate currencies	$ 1,000,000
Annual facility fee for each bank based on commitment amount	0.15%
Maturity Date	May 13, 2021
HCN Term Loan	$ 500,000
HCN Canadian Denomiated Term Loan	250,000
Accordion Feature [Member]
Line Of Credit Facility [Line Items]
HCN Term Loan	1,000,000
HCN Canadian Denomiated Term Loan	$ 250,000
Revolving Credit Facility [Member]
Line Of Credit Facility [Line Items]
Agent bank's prime rate of interest	2.13%
Debt Instrument Basis Spread On Variable Rate1	0.90%
Maturity Date	May 13, 2020
Letter of credit that reduces the borrowing capacity	$ 25,576