DEBT (Narrative) (Details) $ in Thousands		1 Months Ended				3 Months Ended	9 Months Ended
		Aug. 31, 2021 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	May 31, 2020 USD ($)	Jun. 30, 2021 USD ($)	Sep. 30, 2021 USD ($) item	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Discounts and debt issuance costs							$ 12,647	$ 6,028
Total long-term debt - face value			$ 3,357,906				3,957,208	3,357,906	$ 3,357,899
Financing costs			71,399				70,864	71,399	70,224
Net proceeds					$ 741,417
Repayment of long-term debt							1,444,024	250,018
Short-term debt			0				0	0	0
Delayed Draw Term Loan Expires 2024 [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity						$ 1,600,000
Borrowings							$ 1,100,000
Proceeds from line of credit		$ 1,600,000
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							$ 24,850
Supported By Line Of Credit [Member]
Debt Instrument [Line Items]
Outstanding standby letters of credit							$ 58,335
Investment-Grade Type Covenants Governed [Member]
Debt Instrument [Line Items]
Number of indentures with customary investment-grade type covenants | item							3
Bridge Facility And Delayed Draw Term Loan [Member]
Debt Instrument [Line Items]
Discounts and debt issuance costs						9,384
Financing costs							$ 13,316
Line of Credit [Member]
Debt Instrument [Line Items]
Transaction fees			4,632					4,632
Maximum borrowing capacity			$ 1,000,000				$ 1,000,000	1,000,000
Commitment fee							0.10%
Available borrowing capacity							$ 941,665
Debt issued, term			5 years
Short-term debt							$ 0
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						$ 2,200,000
Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Outstanding standby letters of credit							$ 83,185
Period of standby letters of credit							1 year
Self Insurance Reserve							$ 74,794
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			$ 0				$ 1,100,000	0	0
Maturity year	[1]						2024
Notes [Member]
Debt Instrument [Line Items]
Total long-term debt - face value							$ 3,957,208
Notes [Member] | Investment-Grade Type Covenants Governed [Member]
Debt Instrument [Line Items]
Total long-term debt - face value							2,846,188
Notes [Member] | 3.50% notes due 2030 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value			750,000		$ 750,000		$ 750,000	750,000	750,000
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					$ 250,000
Maturity year							2020
Repayment of long-term debt				$ 250,000
Notes [Member] | Floating-Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Total long-term debt - face value			$ 500,000				$ 0	$ 500,000	$ 500,000
Maturity year							2021
Face value							$ 500,000
U.S. Concrete, Inc. [Member] | Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Debt assumed in acquisition		$ 434,463

[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.