Legal Proceedings (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Loss contingencies
Number of sites for state law proceedings under environmental matters		12
Number of sites for proceedings under environmental matters in Brazil		1
Accrual for Environmental Loss Contingencies		$ 300,000	$ 900,000
TaxAssessmentForGoodwillAmortization		9,800,000
After tax income from Brazil court decision		10,100,000.0
Pretax income from Brazil court decision		15,300,000.0
Tax impact of Brazil court decision	$ 5,200,000.0	$ 5,200,000.0