Commitments and Contingencies (Details)			2 Months Ended	3 Months Ended								9 Months Ended	12 Months Ended
	Jun. 23, 2015 USD ($)	Jun. 09, 2015 USD ($)	Oct. 31, 2015 crash_test	Dec. 31, 2015 USD ($) state	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) state lawsuit county	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Mar. 11, 2015 guard_rail	Oct. 20, 2014 crash_test
Loss Contingencies [Line Items]
Revenues				$ 1,547,000,000	$ 1,542,200,000	$ 1,676,800,000	$ 1,626,700,000	$ 1,661,400,000	$ 1,562,800,000	$ 1,485,300,000	$ 1,460,500,000		$ 6,392,700,000	$ 6,170,000,000	$ 4,365,300,000
Minimum possible loss				3,500,000									3,500,000
Maximum possible loss				23,600,000									23,600,000
Non-cancelable purchase obligations				874,800,000									874,800,000
Accrued liabilities
Loss Contingencies [Line Items]
Total accrual				13,600,000									13,600,000
Construction Products Group
Loss Contingencies [Line Items]
Revenues													520,600,000	546,100,000	$ 508,600,000
Rail Inland Barge and Energy Equipment Groups | Inventories
Loss Contingencies [Line Items]
Non-cancelable purchase obligations				$ 744,500,000									$ 744,500,000
Highway products litigation
Loss Contingencies [Line Items]
Number of additional crash tests requested | crash_test																	8
Number of additional crash tests passed, first installation height | crash_test																	4
Number of additional crash tests passed, second installation height | crash_test																	4
Number of devices field measured (more than) | guard_rail																1,000
Number of crash tests performed by VDOT | crash_test			6
Number of standard Report 350 crash tests conducted by VDOT, all passed | crash_test			4
Number of non-standard crash tests, VDOT had concerns about | crash_test			1
Number of non-standard crash tests conducted by VDOT | crash_test			2
Highway products litigation | ET Plus
Loss Contingencies [Line Items]
Number of states that have removed product from qualified products list | state				36									36
Highway products litigation | ET Plus | UNITED STATES
Loss Contingencies [Line Items]
Revenues														$ 35,100,000
Highway products litigation | ET Plus | UNITED STATES | Construction Products Group
Loss Contingencies [Line Items]
Revenues												$ 0
Highway products litigation | ET Plus | UNITED STATES | Construction Products Group | Revenues | Construction Products Group
Loss Contingencies [Line Items]
Percentage of consolidated revenues														0.60%
Environmental and workplace matters
Loss Contingencies [Line Items]
Total accrual				$ 4,300,000									$ 4,300,000
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
Supersedeas bond posted	$ 686,000,000
Supersedeas bond, initial annual premium	$ 3,900,000
Total accrual				0									0
State, county, and municipal actions | Highway products litigation
Loss Contingencies [Line Items]
Total accrual				0									$ 0
Number of additional state qui tam actions filed (in lawsuits) | lawsuit													6
Number of class action lawsuits | lawsuit													4
Number of counties claimed as parties to class action suit | county													101
Compensatory damages sought													$ 400,000,000
Punitive damages sought													100,000,000
Shareholder class actions | Highway products litigation
Loss Contingencies [Line Items]
Total accrual				$ 0									$ 0