Pension and Other Post-Retirement Benefits - Assumptions (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Retiree Health and Life [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, net periodic cost (benefit)	3.67%	3.94%
Retiree Health and Life [Member] | Salaried Health [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation		3.78%
Retiree Health and Life [Member] | Hourly Health [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation		4.09%
Discount rate, net periodic cost (benefit)	4.00%	4.31%
Retiree Health and Life [Member] | Salaried and Hourly Health [Member] [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation	3.40%
Retiree Health and Life [Member] | Salaried Life Insurance [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation		4.18%
Discount rate, net periodic cost (benefit)	4.19%	4.41%
Retiree Health and Life [Member] | Hourly Life Insurance [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation		3.83%
Discount rate, net periodic cost (benefit)	3.84%	4.06%
Retiree Health and Life [Member] | Salaried and Hourly Life Insurance [Member] [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation	3.66%
UNITED STATES | Salaried Funded Plans [Member] [Domain]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation	3.68%	4.22%
UNITED STATES | Unfunded Plan [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation	0.00%	0.00%
UNITED STATES | Hourly Funded Plans [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation	3.73%	4.30%
Discount rate, net periodic cost (benefit)	4.31%	4.52%
Expected return on plan assets, net periodic cost (benefit)	6.15%	6.75%
UNITED STATES | Salaried Funded and Unfunded Plans [Member]
Expected long term return on assets and to measure the periodic cost
Rate of compensation and pension-in-payment increases, benefit obligation	2.50%	2.50%
Discount rate, net periodic cost (benefit)	4.23%	4.47%
Expected return on plan assets, net periodic cost (benefit)	6.25%	6.80%
Rate of compensation and pension-in-payment increases, net periodic cost (benefit)	2.50%	2.50%
Foreign Plan [Member]
Expected long term return on assets and to measure the periodic cost
Discount rate, benefit obligation	2.40%	2.60%
Rate of compensation and pension-in-payment increases, benefit obligation	3.10%	3.20%
Discount rate, net periodic cost (benefit)	2.60%	3.60%
Expected return on plan assets, net periodic cost (benefit)	4.20%	4.80%
Rate of compensation and pension-in-payment increases, net periodic cost (benefit)	3.20%	3.00%