Revenue Recognition (Tables)

12 Months Ended

Dec. 31, 2019

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)	2019
Mid-America Group	$	1,328.8	$	117.2	$	1,446.0
Southeast Group		489.1		17.3		506.4
West Group		2,354.5		160.9		2,515.4
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
Mid-America Group	$	1,133.8	$	89.4	$	1,223.2
Southeast Group		409.6		13.8		423.4
West Group		2,168.4		141.6		2,310.0
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
	2017
Mid-America Group	$	982.2	$	71.1	$	1,053.3
Southeast Group		348.7		13.9		362.6
West Group		2,139.9		139.8		2,279.7
Total Building Materials Business		3,470.8		224.8		3,695.6
Magnesia Specialties		252.7		17.3		270.0
Total	$	3,723.5	$	242.1	$	3,965.6

Summary of Information About the Company's Contract Balances

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

December 31
(in millions)	2019		2018
Costs in excess of billings	$	2.8	$	2.0
Billings in excess of costs	$	7.8	$	6.7