DEBT (Narrative) (Details) $ in Millions	1 Months Ended				3 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($)	Aug. 31, 2021 USD ($)	Jun. 30, 2020 USD ($)	May 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2021 USD ($)
Debt Instrument [Line Items]
Discounts and debt issuance costs						$ 13.9	$ 7.2
Total long-term debt - face value						3,949.6	3,357.8
Financing costs						69.6	70.2
Net proceeds				$ 741.4
Repayment of long-term debt						1,451.7	250.0	$ 0.0
Short-term debt						0.0	0.0
Self Insurance Reserve						$ 137.7	75.6
Delayed Draw Term Loan Expires 2024 [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity									$ 1,600.0
Borrowings	$ 1,100.0
Proceeds from line of credit		$ 1,600.0
Delayed Draw Term Loan Expires 2024 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						1.00%
Delayed Draw Term Loan Expires 2024 [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						0.00%
Letters Of Credit, Expire July 2022 [Member]
Debt Instrument [Line Items]
Self Insurance Reserve						$ 24.8
Supported By Line Of Credit [Member]
Debt Instrument [Line Items]
Outstanding standby letters of credit						$ 59.6
Investment-Grade Type Covenants Governed [Member]
Debt Instrument [Line Items]
Number of indentures with customary investment-grade type covenants | item						2
Bridge Facility And Delayed Draw Term Loan [Member]
Debt Instrument [Line Items]
Discounts and debt issuance costs						$ 9.4
Financing costs						13.3
Line of Credit [Member]
Debt Instrument [Line Items]
Transaction fees					$ 4.6
Maximum borrowing capacity					$ 1,000.0	$ 1,000.0
Commitment fee						0.10%
Available borrowing capacity						$ 940.4
Borrowings						$ 0.0
Debt issued, term					5 years
Line of Credit [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						1.125%
Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						0.125%
Bridge Facility [Member]
Debt Instrument [Line Items]
Face value									$ 2,200.0
Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Outstanding standby letters of credit						$ 84.4
Period of standby letters of credit						1 year
Self Insurance Reserve						$ 76.0
Standby Letters of Credit [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						0.175%
Maximum [Member] | Delayed Draw Term Loan Expires 2024 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						1.375%
Maximum [Member] | Delayed Draw Term Loan Expires 2024 [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						0.375%
Maximum [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Commitment fee						0.225%
Maximum [Member] | Line of Credit [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						1.625%
Maximum [Member] | Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						0.625%
Minimum [Member] | Delayed Draw Term Loan Expires 2024 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						0.875%
Minimum [Member] | Delayed Draw Term Loan Expires 2024 [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						0.00%
Minimum [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Commitment fee						0.09%
Minimum [Member] | Line of Credit [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						1.00%
Minimum [Member] | Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate						0.00%
Term Loan Due [Member] | Delayed Draw Term Loan Expires 2024 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value						$ 1,100.0	$ 0.0
Maturity year						2024	2024
Notes [Member]
Debt Instrument [Line Items]
Total long-term debt - face value						$ 3,949.6
Notes [Member] | Delayed Draw Term Loan Expires 2024 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value						1,100.0
Notes [Member] | Investment-Grade Type Covenants Governed [Member]
Debt Instrument [Line Items]
Total long-term debt - face value						2,840.2
Notes [Member] | 3.50% notes due 2030 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value				$ 750.0		$ 750.0	$ 750.0
Maturity year				2030		2030
Interest rate				3.50%		3.50%
Notes [Member] | Floating-Rate Notes Due 2020 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value				$ 250.0
Maturity year						2020
Repayment of long-term debt			$ 250.0
Notes [Member] | Floating-Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value						$ 0.0	$ 500.0
Maturity year						2021
Face value						$ 500.0
U.S. Concrete, Inc. [Member] | Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Repayments of debt	$ 434.5
Debt assumed in acquisition		$ 434.5