Borrowings Under Line of Credit Arrangements and Related Items (Details Textual)	3 Months Ended
	Mar. 31, 2014 USD ($) Number	Mar. 31, 2014 CAD	Mar. 31, 2014 GBP (£)
Line Of Credit Facility [Line Items]
Unsecured line of credit arrangement	$ 2,250,000,000
Additional unsecured line of credit arrangement	1,000,000,000
Maximum aggregate commitment	3,250,000,000
Number of banks in consortium	30	30	30
Maximum Interest payable period in months	3	3	3
Available to borrow in alternate currencies	500,000,000
Agent bank's prime rate of interest	1.33%	1.33%	1.33%
Interest Rate margin	1.175%	1.175%	1.175%
Annual facility fee for each bank based on commitment amount	0.225%	0.225%	0.225%
Debt instrument maturity date	Mar. 31, 2017	Mar. 31, 2017	Mar. 31, 2017
Balance outstanding at quarter end	$ 562,000,000	0	£ 0