Employee Benefits - Schedule of Other information related to Company's other post-retirement plan's (Details) - U.S. and Canadian Other Post-Retirement Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost recognized (millions)	$ 1	$ 5	$ 6
Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average discount rate used to determine future benefit obligations	3.32%	3.71%	3.99%
Weighted-average discount rate used to determine net periodic benefit costs	3.71%	3.99%	3.83%
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average discount rate used to determine future benefit obligations	3.64%	4.15%	4.33%
Weighted-average discount rate used to determine net periodic benefit costs	4.15%	4.33%	4.08%