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Alabama State Industrial Development Authority Financing and Economic Incentives - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended
Jan. 02, 2020
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2008
Jan. 13, 1995
Debt Instrument [Line Items]          
Repayment of bond     $ 24,600    
Taxable Revenue Bonds [Member]          
Debt Instrument [Line Items]          
Proceeds from state industrial development authority issued taxable bonds loaned to ADTRAN       $ 50,000 $ 20,000
Percentage of interest on bond   2.00%      
Maturity date of bond   Jan. 01, 2020      
Repayment of bond $ 24,600