Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2020

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. Prior-year segment information has been reclassified to conform to the reporting structure change described in Note 1.

	Three Months Ended
	March 31, 2020
	Products and Services		Freight		Total
	(Dollars in Millions)
Mid-America Group	$	241.0	$	19.8	$	260.8
Southeast Group		116.9		4.2		121.1
West Group		473.2		37.4		510.6
Total Building Materials Business		831.1		61.4		892.5
Magnesia Specialties		59.9		5.8		65.7
Total	$	891.0	$	67.2	$	958.2
	Three Months Ended
	March 31, 2019
	Products and Services		Freight		Total
	(Dollars in Millions)
Mid-America Group	$	229.6	$	18.5	$	248.1
Southeast Group		115.3		3.9		119.2
West Group		464.2		33.4		497.6
Total Building Materials Business		809.1		55.8		864.9
Magnesia Specialties		69.2		4.9		74.1
Total	$	878.3	$	60.7	$	939.0

Summary of Information About the Company's Contract Balances

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

(Dollars in Millions)	March 31, 2020		December 31, 2019
Costs in excess of billings	$	3.8	$	2.8
Billings in excess of costs	$	5.4	$	7.8