Loans and Allowance for Credit Losses - Schedule of Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2019
Recorded Investment
Total		$ 109,239
Unpaid Principal Balance
Total		110,353
Related Allowance		8,991
Average Recorded Investment
Total	$ 121,139
Commercial
Recorded Investment
With no related allowance recorded		23,227
With an allowance recorded		18,252
Unpaid Principal Balance
With no related allowance recorded		23,665
With an allowance recorded		18,305
Related Allowance		7,891
Average Recorded Investment
With no related allowance recorded	23,688
With an allowance recorded	11,347
Commercial real estate
Recorded Investment
With an allowance recorded		12,685
Unpaid Principal Balance
With an allowance recorded		12,685
Related Allowance		1,006
Commercial real estate \| Real Estate - Construction
Recorded Investment
With no related allowance recorded		12,929
Unpaid Principal Balance
With no related allowance recorded		12,929
Average Recorded Investment
With no related allowance recorded	5,477
With an allowance recorded	8,690
Commercial real estate \| Real Estate - Other
Recorded Investment
With no related allowance recorded		37,674
Unpaid Principal Balance
With no related allowance recorded		38,112
Average Recorded Investment
With no related allowance recorded	40,135
With an allowance recorded	26,279
Residential real estate
Recorded Investment
With no related allowance recorded		1,774
With an allowance recorded		1,201
Unpaid Principal Balance
With no related allowance recorded		1,794
With an allowance recorded		1,201
Related Allowance		39
Average Recorded Investment
With no related allowance recorded	2,289
With an allowance recorded	881
Consumer
Recorded Investment
With no related allowance recorded		403
With an allowance recorded		1,094
Unpaid Principal Balance
With no related allowance recorded		568
With an allowance recorded		1,094
Related Allowance		$ 55
Average Recorded Investment
With no related allowance recorded	660
With an allowance recorded	$ 1,693

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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