Revenue Recognition (Tables)

9 Months Ended

Sep. 30, 2021

Revenue From Contract With Customer [Abstract]

Schedule of Company's Total Revenues by Category for each Reportable Segment

The following table presents the Company’s total revenues by category for each reportable segment.

	Three Months Ended
	September 30, 2021
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	641.8	$	42.3	$	684.1
West Group		749.0		45.8		794.8
Total Building Materials business		1,390.8		88.1		1,478.9
Magnesia Specialties		71.9		6.5		78.4
Total	$	1,462.7	$	94.6	$	1,557.3
	Three Months Ended
	September 30, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	514.1	$	35.2	$	549.3
West Group		671.4		39.8		711.2
Total Building Materials business		1,185.5		75.0		1,260.5
Magnesia Specialties		55.2		5.7		60.9
Total	$	1,240.7	$	80.7	$	1,321.4

	Nine Months Ended
	September 30, 2021
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	1,610.9	$	103.5	$	1,714.4
West Group		1,861.9		116.3		1,978.2
Total Building Materials business		3,472.8		219.8		3,692.6
Magnesia Specialties		207.1		17.9		225.0
Total	$	3,679.9	$	237.7	$	3,917.6
	Nine Months Ended
	September 30, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
East Group	$	1,371.8	$	94.1	$	1,465.9
West Group		1,785.4		118.8		1,904.2
Total Building Materials business		3,157.2		212.9		3,370.1
Magnesia Specialties		164.0		16.2		180.2
Total	$	3,321.2	$	229.1	$	3,550.3

Summary of Information About the Company's Contract Balances

The following table presents information about the Company’s contract balances:

(Dollars in Millions)	September 30, 2021		December 31, 2020
Costs in excess of billings	$	10.8	$	2.2
Billings in excess of costs	$	10.7	$	14.0