Debt	6 Months Ended
Jun. 30, 2017
Debt Disclosure [Abstract]
Debt	Debt Revolving credit facility Effective June 23, 2017, the Company extended the maturity date by one year on its existing revolving U.S. $2.0 billion credit facility, which includes a U.S. $1.0 billion five-year portion and U.S. $1.0 billion one-year plus one-year term-out portion. The maturity date on the U.S. $1.0 billion one-year plus one-year term-out portion has been extended to June 27, 2019; the maturity date on the U.S. $1.0 billion five-year portion was extended to June 28, 2022. Commercial paper program The Company has a commercial paper program which enables it to issue commercial paper up to a maximum aggregate principal amount of U.S. $1.0 billion in the form of unsecured promissory notes. The commercial paper is backed by the U.S. $1.0 billion one-year plus one-year term-out portion of the revolving credit facility. As at June 30, 2017 and December 31, 2016, the Company had no commercial paper borrowings. The Company presents issuances and repayments of commercial paper in the Interim Consolidated Statements of Cash Flows on a net basis, all of which have a maturity of less than 90 days.

Debt

6 Months Ended

Jun. 30, 2017

Revolving credit facility

Effective June 23, 2017, the Company extended the maturity date by one year on its existing revolving U.S. $2.0 billion credit facility, which includes a U.S. $1.0 billion five-year portion and U.S. $1.0 billion one-year plus one-year term-out portion. The maturity date on the U.S. $1.0 billion one-year plus one-year term-out portion has been extended to June 27, 2019; the maturity date on the U.S. $1.0 billion five-year portion was extended to June 28, 2022.

Commercial paper program

The Company has a commercial paper program which enables it to issue commercial paper up to a maximum aggregate principal amount of U.S. $1.0 billion in the form of unsecured promissory notes. The commercial paper is backed by the U.S. $1.0 billion one-year plus one-year term-out portion of the revolving credit facility. As at June 30, 2017 and December 31, 2016, the Company had no commercial paper borrowings.

The Company presents issuances and repayments of commercial paper in the Interim Consolidated Statements of Cash Flows on a net basis, all of which have a maturity of less than 90 days.