DEBT (Narrative) (Details) $ in Millions		1 Months Ended	3 Months Ended
		Aug. 31, 2021 USD ($)	Mar. 31, 2022 USD ($) item	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Discounts and debt issuance costs			$ 1.3		$ 1.1
Total long-term debt - face value			3,947.2		2,857.4	$ 3,949.6
Financing costs			68.8		69.1	69.6
Short-term debt			100.0		0.0	0.0
Delayed Draw Term Loan Expires 2026 [Member]
Debt Instrument [Line Items]
Borrowings			$ 1,100.0
Proceeds from line of credit		$ 1,600.0
Delayed Draw Term Loan Expires 2026 [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.00%
Delayed Draw Term Loan Expires 2026 [Member] | SOFR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.975%
Letters Of Credit, Expire July 2022 [Member]
Debt Instrument [Line Items]
Self Insurance Reserve			$ 24.9
Supported By Line Of Credit [Member]
Debt Instrument [Line Items]
Outstanding standby letters of credit			$ 69.6
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]
Maximum borrowing capacity			$ 1,000.0
Commitment fee			0.10%
Available borrowing capacity			$ 830.4
Short-term debt			$ 100.0
Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.125%
Line of Credit [Member] | SOFR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			1.125%
Line of Credit [Member] | Unsecured Line Of Credit, Maturity Of September 2026 [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 1,000.0
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			$ 94.5
Period of standby letters of credit			1 year
Self Insurance Reserve			$ 86.0
Standby Letters of Credit [Member] | SOFR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.175%
Maximum [Member] | Delayed Draw Term Loan Expires 2026 [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.25%
Maximum [Member] | Delayed Draw Term Loan Expires 2026 [Member] | SOFR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			1.35%
Maximum [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Commitment fee			0.225%
Maximum [Member] | Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.625%
Maximum [Member] | Line of Credit [Member] | SOFR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			1.725%
Minimum [Member] | Delayed Draw Term Loan Expires 2026 [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.00%
Minimum [Member] | Delayed Draw Term Loan Expires 2026 [Member] | SOFR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.85%
Minimum [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Commitment fee			0.09%
Minimum [Member] | Line of Credit [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			0.00%
Minimum [Member] | Line of Credit [Member] | SOFR [Member]
Debt Instrument [Line Items]
Applicable margin on borrowing rate			1.10%
Term Loan Due [Member] | Delayed Draw Term Loan Expires 2026 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value			$ 1,100.0		$ 0.0	$ 1,100.0
Maturity year	[1]		2026
Notes [Member]
Debt Instrument [Line Items]
Total long-term debt - face value			$ 3,947.2
Notes [Member] | Delayed Draw Term Loan Expires 2026 [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 1,600.0
Notes [Member] | Investment-Grade Type Covenants Governed [Member]
Debt Instrument [Line Items]
Total long-term debt - face value			$ 2,840.2
U.S. Concrete, Inc. [Member] | Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Debt assumed in acquisition		$ 434.5

[1] Borrowings on the bank line of credit are classified as short-term if we intend to repay within twelve months and as long-term if we have the intent and ability to extend payment beyond twelve months.