Revenue Recognition (Tables)

12 Months Ended

Dec. 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:

years ended December 31	Products and Services		Freight		Total
(in millions)	2020
East Group	$	1,826.6	$	122.5	$	1,949.1
West Group		2,384.6		153.5		2,538.1
Total Building Materials business		4,211.2		276.0		4,487.2
Magnesia Specialties		220.9		21.8		242.7
Total	$	4,432.1	$	297.8	$	4,729.9
	2019
East Group	$	1,814.5	$	134.5	$	1,949.0
West Group		2,357.9		160.9		2,518.8
Total Building Materials business		4,172.4		295.4		4,467.8
Magnesia Specialties		249.9		21.4		271.3
Total	$	4,422.3	$	316.8	$	4,739.1
	2018
East Group	$	1,539.8	$	103.3	$	1,643.1
West Group		2,172.0		141.5		2,313.5
Total Building Materials business		3,711.8		244.8		3,956.6
Magnesia Specialties		268.6		19.1		287.7
Total	$	3,980.4	$	263.9	$	4,244.3

Summary of Information About the Company's Contract Balances

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

December 31
(in millions)	2020		2019
Costs in excess of billings	$	2.2	$	2.8
Billings in excess of costs	$	14.0	$	7.8