Pension and Other Postretirement Benefits, Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Effect of one percentage point increase on total service and interest cost		$ 0
Effect of one percentage point decrease on total service and interest cost		0
Effect of one percentage point increase on postretirement benefit obligations		5
Effect of one percentage point decrease on postretirement benefit obligations		$ (4)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	[1]	4.40%	4.67%	4.14%
Service cost		4.55%	4.83%	0.00%	[2]
Interest cost		3.84%	3.95%	0.00%	[2]
Expected long-term return on plan assets	[3]	7.92%	7.92%	8.14%
Rate of compensation increase	[4]	3.50%	3.50%	3.50%
Pension Plans [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation		4.45%	4.73%	4.20%
Expected long-term return on plan assets		8.00%	8.00%	8.25%
Rate of compensation increase		3.50%	3.50%	3.50%
Health care cost trend rate, covering retirees under 65 years of age next fiscal year		6.50%
Health care cost trend rate, covering retirees over 65 years of age next fiscal year		8.00%
Pension Plans [Member] | U.S. [Member] | 2021 and Thereafter [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate, covering retirees under 65 years of age		5.00%
Pension Plans [Member] | U.S. [Member] | 2024 and Thereafter [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate, covering retirees over 65 years of age		5.00%
Pension Plans [Member] | Canada [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation		3.79%	3.93%	3.90%
Expected long-term return on plan assets		7.25%	7.25%	7.25%
Rate of compensation increase		3.50%	3.50%	3.50%
Health care cost trend rate next fiscal year		6.25%
Pension Plans [Member] | Canada [Member] | 2023 and Thereafter [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate		5.00%
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	[5]	4.05%	4.22%	3.70%
Service cost		4.21%	4.37%	0.00%	[2]
Interest cost		3.26%	3.26%	0.00%	[2]
Expected long-term return on plan assets		7.43%	7.42%	7.65%
Postretirement Benefit Plans [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation		4.11%	4.28%	3.70%
Postretirement Benefit Plans [Member] | Canada [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation		3.64%	3.74%	3.70%

[1] The weighted average discount rate assumptions used for the years ended December 31, 2017, 2016, and 2015 were comprised of separate assumptions determined by country of 4.45%, 4.73% and 4.20% for the U.S. based plans and 3.79%, 3.93% and 3.90% for the Canadian based plans, respectively.

[2] Not applicable as the Company changed to the spot rate approach beginning in 2016 as described above.

[3] The weighted average expected long-term return on plan assets assumptions used were comprised of separate assumptions determined by country of 8.00% for each of the years ended December 31, 2017 and 2016 and 8.25% for the year ended December 31, 2015 for the U.S. based plans and 7.25% for the Canadian based plans for the years ended December 31, 2017, 2016 and 2015.

[4] The weighted average rate of compensation increase assumptions used for the years ended December 31, 2017, 2016 and 2015 were comprised of separate assumptions determined by country of 3.50% for both the U.S and Canadian based plans.

[5] The weighted average discount rate assumptions used for the years ended December 31, 2017, 2016 and 2015 were comprised of separate assumptions determined by country of 4.11%, 4.28% and 3.70% for the U.S. based plans and 3.64%, 3.74% and 3.70% for the Canadian based plans, respectively.