SEGMENT INFORMATION - Schedule of Revenue by Product (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from External Customer [Line Items]
Revenue	$ 369.2	$ 408.9	$ 367.5	$ 333.1	$ 370.1	$ 404.3	$ 404.2	$ 327.8	$ 1,478.7	$ 1,506.4	$ 1,336.0
Ready-mixed concrete
Revenue from External Customer [Line Items]
Revenue									1,278.6	1,306.5	1,213.0
Aggregate products
Revenue from External Customer [Line Items]
Revenue									141.7	136.5	49.8
Aggregates distribution
Revenue from External Customer [Line Items]
Revenue									22.5	22.7	30.6
Building materials
Revenue from External Customer [Line Items]
Revenue									28.9	26.2	24.4
Lime
Revenue from External Customer [Line Items]
Revenue									0.0	7.4	9.9
Hauling
Revenue from External Customer [Line Items]
Revenue									4.3	4.8	5.6
Other
Revenue from External Customer [Line Items]
Revenue									$ 2.7	$ 2.3	$ 2.7