QUARTERLY SUMMARY (unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Quarterly Financial Information Disclosure [Abstract]
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
Operating income	18.0	33.3	6.0	7.9	16.7	35.0	30.6	7.6	65.2	89.9	79.0
Net income (loss)	4.4	13.6	0.9	(2.6)	3.1	15.8	16.3	(3.9)	16.3	31.3	25.6
Net income (loss) attributable to U.S. Concrete	$ 3.9	$ 13.0	$ 0.7	$ (2.7)	$ 2.0	$ 15.6	$ 16.3	$ (3.9)	$ 14.9	$ 30.0	$ 25.5
Net income (loss) per share attributable to U.S. Concrete - basic (in dollars per share)	$ 0.24	$ 0.79	$ 0.04	$ (0.16)	$ 0.12	$ 0.95	$ 0.99	$ (0.23)	$ 0.91	$ 1.82	$ 1.60
Net income (loss) per share attributable to U.S. Concrete - diluted (in dollars per share)	$ 0.23	$ 0.79	$ 0.04	$ (0.16)	$ 0.12	$ 0.94	$ 0.99	$ (0.23)	$ 0.91	$ 1.82	$ 1.53
Gain on sale of businesses						$ 14.6				$ (1.0)
General insurance expense	$ 6.0