Annual report pursuant to Section 13 and 15(d)

Benefit Plans - Weighted Average Assumptions for Pension Obligation (Details)

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Benefit Plans - Weighted Average Assumptions for Pension Obligation (Details)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation    
Immediate trend rate 6.20% 6.84%
Ultimate trend rate 4.50% 4.50%
Year that the rate reaches ultimate trend rate 2037 2035
Defined Benefit Pension Plans | U.S.    
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation    
Discount rate 3.74% 4.24%
Rate of compensation increase 3.00% 3.00%
Defined Benefit Pension Plans | U.S. | Eco Services Hourly Pension Plan    
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation    
Rate of compensation increase 3.00% 3.00%
Defined Benefit Pension Plans | Foreign    
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation    
Discount rate 2.91% 2.99%
Rate of compensation increase 2.57% 2.97%
Supplemental Retirement Plans    
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation    
Discount rate 3.60% 3.90%
Other Postretirement Benefits Plans    
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation    
Discount rate 3.53% 3.74%