SEGMENT INFORMATION - Revenue by Product (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Total revenue	$ 408.9	$ 404.3	$ 1,109.5	$ 1,136.3
Ready-mixed concrete
Segment Reporting Information [Line Items]
Total revenue	354.1	346.3	958.5	985.5
Aggregate products
Segment Reporting Information [Line Items]
Total revenue	37.9	41.1	105.8	100.9
Aggregates distribution
Segment Reporting Information [Line Items]
Total revenue	6.5	6.1	18.2	16.5
Building materials
Segment Reporting Information [Line Items]
Total revenue	8.6	7.0	21.5	20.2
Lime
Segment Reporting Information [Line Items]
Total revenue	0.0	1.9	0.0	7.4
Hauling
Segment Reporting Information [Line Items]
Total revenue	1.2	1.2	3.5	3.9
Other
Segment Reporting Information [Line Items]
Total revenue	$ 0.6	$ 0.7	$ 2.0	$ 1.9