Commitments and Contingencies - Commitments and Contingencies (Details)		3 Months Ended								12 Months Ended
	Jun. 09, 2015 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) lawsuit	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Loss Contingency, Receivable		$ 16,900,000								$ 16,900,000
Revenues		735,000,000	$ 606,900,000	$ 634,000,000	$ 533,200,000	$ 615,400,000	$ 655,700,000	$ 595,700,000	$ 530,600,000	2,509,100,000	$ 2,397,400,000	$ 3,089,800,000
Non-cancelable purchase obligations		834,800,000								834,800,000
Accrued liabilities
Loss Contingencies [Line Items]
Total accrual		29,600,000								29,600,000
Rail Inland Barge and Energy Equipment Groups | Inventories
Loss Contingencies [Line Items]
Non-cancelable purchase obligations		763,900,000								763,900,000
Environmental and workplace matters
Loss Contingencies [Line Items]
Total accrual		1,600,000								$ 1,600,000
Joshua Harman, False Claims Act | Highway products litigation
Loss Contingencies [Line Items]
Damages awarded by jury verdict	$ 175,000,000
Judgment entered	682,400,000
Damages awarded by jury verdict, automatically trebled under the Act	525,000,000
Judgment entered, civil penalties	138,400,000
Judgment entered, costs and attorney fees	$ 19,000,000
State, county, and municipal actions | Highway products litigation
Loss Contingencies [Line Items]
Number of additional state qui tam actions filed (in lawsuits) | lawsuit										13
Shareholder class actions | Highway products litigation
Loss Contingencies [Line Items]
Total accrual		0								$ 0
Minimum
Loss Contingencies [Line Items]
Range of reasonably possible losses		23,300,000								23,300,000
Maximum
Loss Contingencies [Line Items]
Range of reasonably possible losses		$ 45,900,000								$ 45,900,000