Contingencies - Narrative (Details) - USD ($)	Jun. 09, 2015	Sep. 30, 2019
Loss Contingencies [Line Items]
Loss Contingency, Receivable		$ 24,000,000.0
Accrued liabilities
Loss Contingencies [Line Items]
Loss Contingency Accrual		33,800,000
Highway Products Litigation | False Claims Act, USA
Loss Contingencies [Line Items]
Damages awarded by jury verdict	$ 175,000,000.0
Total amount of judgment entered by the District Court	682,400,000
Damages awarded by jury verdict, automatically trebled under the Act	525,000,000.0
Civil penalties included in judgment entered by the District Court	138,400,000
Costs and attorney's fees included in judgment entered by the District Court	$ 19,000,000.0
Highway Products Litigation | State, county, and municipal actions
Loss Contingencies [Line Items]
Loss Contingency Accrual		0
Class Action, Shareholder | Class Action, Shareholder
Loss Contingencies [Line Items]
Loss Contingency Accrual		7,500,000
Loss Contingency Accrual, Net of Insurance Receivable		2,500,000
Environmental and workplace matters
Loss Contingencies [Line Items]
Loss Contingency Accrual		1,400,000
Minimum
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss		29,600,000
Maximum
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss		$ 46,200,000