Annual report pursuant to Section 13 and 15(d)

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Company's Earn-Out Liability (Details)

v3.20.4
Fair Value of Financial Instruments - Summary of Changes in Fair Value of Company's Earn-Out Liability (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Earn-out payments during period $ 3,946 $ 3,627
Level 3 Inputs    
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning balance 9,154 7,610
Fair value of the earn-out liability associated with the American Stainless (ASTI) acquisition   6,366
Earn-out payments during period (4,238) (4,075)
Changes in fair value during the period (1,195) (747)
Ending balance 3,721 9,154
MUSA-Stainless | Level 3 Inputs    
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning balance 2,403 4,252
Fair value of the earn-out liability associated with the American Stainless (ASTI) acquisition   0
Earn-out payments during period (1,625) (1,634)
Changes in fair value during the period (403) (215)
Ending balance 375 2,403
MUSA-Galvanized | Level 3 Inputs    
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning balance 1,782 3,358
Fair value of the earn-out liability associated with the American Stainless (ASTI) acquisition   0
Earn-out payments during period (611) (712)
Changes in fair value during the period (230) (864)
Ending balance 941 1,782
American Stainless | Level 3 Inputs    
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Beginning balance 4,969 0
Fair value of the earn-out liability associated with the American Stainless (ASTI) acquisition   6,366
Earn-out payments during period (2,002) (1,729)
Changes in fair value during the period (562) 332
Ending balance $ 2,405 $ 4,969