SEGMENT INFORMATION - Schedule of Cap Ex by Product (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Capital expenditures	$ 42.7	$ 39.9	$ 42.7
Operating Segments | Ready-mixed concrete
Segment Reporting Information [Line Items]
Capital expenditures	18.0	24.0	21.7
Operating Segments | Aggregate Products Segment
Segment Reporting Information [Line Items]
Capital expenditures	23.6	13.8	18.9
Corporate And Eliminations
Segment Reporting Information [Line Items]
Capital expenditures	$ 1.1	$ 2.1	$ 2.1