Loans - TDRs and Related Allowance for Loan Losses by Loan Class (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable Allowance For Credit Losses [Line Items]
Non-Accrual	$ 30,071	$ 41,624
TDR Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Non-Accrual	23,162	29,101
Restructured and Accruing	7,641	18,592
Total	30,803	47,693
Allowance for Loan Losses Allocated	1,816	3,813
Agricultural Loans \| TDR Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Non-Accrual	21,379	27,223
Restructured and Accruing	4,784	15,690
Total	26,163	42,913
Allowance for Loan Losses Allocated	1,595	3,494
Commercial Real Estate Loans \| TDR Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Non-Accrual	1,756	1,810
Restructured and Accruing	966	984
Total	2,722	2,794
Allowance for Loan Losses Allocated	217	315
Commercial Loans \| TDR Loans
Financing Receivable Allowance For Credit Losses [Line Items]
Non-Accrual	27	68
Restructured and Accruing	1,891	1,918
Total	1,918	1,986
Allowance for Loan Losses Allocated	$ 4	$ 4

County Bancorp, Inc. 10-Q