ASSET RETIREMENT OBLIGATIONS	9 Months Ended
Sep. 30, 2021
ASSET RETIREMENT OBLIGATIONS [Abstract]
ASSET RETIREMENT OBLIGATIONS	Note 9: Asset Retirement Obligations Asset retirement obligations (AROs) are legal obligations associated with the retirement of long-lived assets resulting from the acquisition, construction, development and/or normal use of the underlying assets, including legal obligations for land reclamation at both owned properties and mineral leases. Recognition of a liability for an ARO is required in the period in which it is incurred at its estimated fair value. The associated asset retirement costs are capitalized as part of the carrying amount of the underlying asset and depreciated over the estimated useful life of the asset. The liability is accreted through charges to operating expenses. If the ARO is settled for other than the carrying amount of the liability, we recognize a gain or loss on settlement. ARO operating costs related to accretion of the liabilities and depreciation of the assets are as follows: Three Months Ended Nine Months Ended September 30 September 30in thousands2021 2020 2021 2020 ARO Operating Costs Accretion$ 3,341 $ 3,115 $ 9,796 $ 9,270 Depreciation 2,916 2,123 8,241 6,022 Total$ 6,257 $ 5,238 $ 18,037 $ 15,292 ARO operating costs are reported in cost of revenues. AROs are reported within other noncurrent liabilities in our accompanying Condensed Consolidated Balance Sheets. Reconciliations of the carrying amounts of our AROs are as follows: Three Months Ended Nine Months Ended September 30 September 30in thousands2021 2020 2021 2020 Asset Retirement Obligations Balance at beginning of period$ 286,435 $ 263,748 $ 283,163 $ 210,323 Liabilities incurred 10,712 353 11,650 353 Liabilities settled (5,321) (2,459) (10,274) (11,047) Accretion expense 3,341 3,115 9,796 9,270 Revisions, net 3,165 (5,809) 3,997 50,049 Balance at end of period$ 298,332 $ 258,948 $ 298,332 $ 258,948 ARO liabilities incurred during 2021 primarily relate to those assumed in the acquisition of U.S. Concrete (see Note 16). ARO revisions during the first nine months of 2020 primarily include increases in estimated costs at two aggregates locations, including reclamation activities required under a development agreement at an aggregates site on owned property in Southern California. The reclamation required under the development agreement will result in the restoration of previously mined property to conditions suitable for retail and commercial development.

ASSET RETIREMENT OBLIGATIONS

9 Months Ended

Sep. 30, 2021

ASSET RETIREMENT OBLIGATIONS [Abstract]

Note 9: Asset Retirement Obligations Asset retirement obligations (AROs) are legal obligations associated with the retirement of long-lived assets resulting from the acquisition, construction, development and/or normal use of the underlying assets, including legal obligations for land reclamation at both owned properties and mineral leases. Recognition of a liability for an ARO is required in the period in which it is incurred at its estimated fair value. The associated asset retirement costs are capitalized as part of the carrying amount of the underlying asset and depreciated over the estimated useful life of the asset. The liability is accreted through charges to operating expenses. If the ARO is settled for other than the carrying amount of the liability, we recognize a gain or loss on settlement. ARO operating costs related to accretion of the liabilities and depreciation of the assets are as follows: Three Months Ended Nine Months Ended September 30 September 30in thousands2021 2020 2021 2020 ARO Operating Costs Accretion$ 3,341 $ 3,115 $ 9,796 $ 9,270 Depreciation 2,916 2,123 8,241 6,022 Total$ 6,257 $ 5,238 $ 18,037 $ 15,292 ARO operating costs are reported in cost of revenues. AROs are reported within other noncurrent liabilities in our accompanying Condensed Consolidated Balance Sheets. Reconciliations of the carrying amounts of our AROs are as follows: Three Months Ended Nine Months Ended September 30 September 30in thousands2021 2020 2021 2020 Asset Retirement Obligations Balance at beginning of period$ 286,435 $ 263,748 $ 283,163 $ 210,323 Liabilities incurred 10,712 353 11,650 353 Liabilities settled (5,321) (2,459) (10,274) (11,047) Accretion expense 3,341 3,115 9,796 9,270 Revisions, net 3,165 (5,809) 3,997 50,049 Balance at end of period$ 298,332 $ 258,948 $ 298,332 $ 258,948 ARO liabilities incurred during 2021 primarily relate to those assumed in the acquisition of U.S. Concrete (see Note 16). ARO revisions during the first nine months of 2020 primarily include increases in estimated costs at two aggregates locations, including reclamation activities required under a development agreement at an aggregates site on owned property in Southern California. The reclamation required under the development agreement will result in the restoration of previously mined property to conditions suitable for retail and commercial development.