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Discontinued Operations and Other Dispositions - Summary of Revenue and Operating Earnings (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2021
Dec. 31, 2020
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2021
Mar. 31, 2020
Mar. 31, 2019
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]                      
Revenue $ 343,302 $ 404,667 $ 447,684 $ 426,989 $ 305,195 $ 342,904 $ 400,569 $ 355,365 $ 1,622,642 $ 1,404,033 $ 1,310,254
Operating Earnings (Loss)                 445,796 385,251 386,667
Mathews Readymix LLC and Western Aggregates LLC [Member]                      
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]                      
Revenue                 1,692 32,255 27,790
Operating Earnings (Loss)                 $ 142 $ 4,837 $ 2,481