Employee Benefits - U.S. and Canadian Other Post-Retirement Benefits Narrative (Details) - U.S. and Canadian Other Post-Retirement Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Unrecognized prior-service cost	$ 1.0	$ 1.0
Future amortization of gain	1.7
Future amortization of prior service credit	0.1
Expected employer contributions during next fiscal year	5.0
Expected future benefit payments 2019	5.0
Expected future benefit payments 2020	4.0
Expected future benefit payments 2021	4.0
Expected future benefit payments 2022	4.0
Expected future benefit payments 2024-2028	25.0
Effect of one percentage point increase on accumulated postretirement benefit obligation	5.0
Effect of one percentage point decrease on accumulated postretirement benefit obligation	5.0
Effect of one percentage point increase on service cost and interest cost components of net periodic benefit cost	0.5
Effect of one percentage point decrease on service cost and interest cost components of net periodic benefit cost	$ 0.4
Maximum percentage of liability for future plan cost increases for pre-65 and medical supplement plan coverage	5.00%
Maximum percentage of medical supplement plan into future periods	5.00%
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum percentage of liability for future plan cost increases for pre-65 and medical supplement plan coverage	7.00%
Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum percentage of liability for future plan cost increases for pre-65 and medical supplement plan coverage	4.00%