Loans and Other Real Estate - Impaired Loans with and without Specific Allowances (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Recorded Investment in Impaired Loans	$ 17,653	$ 19,702
Contractual Unpaid Principal Balance	18,697	21,360
Related Allowance	226	338
Average Investment in Impaired Loans	17,460	20,012
Interest Income Recognized	342	592
Commercial, secured by real estate
Financing Receivable, Impaired [Line Items]
Loans without related allowance, Recorded Investment in Impaired Loans	10,886	9,284
Loans with related allowance, Recorded Investment in Impaired Loans	2,934	7,270
Recorded Investment in Impaired Loans	13,820	16,554
Loans without related allowance, Contractual Unpaid Principal Balance	11,457	9,829
Loans with related allowance, Contractual Unpaid Principal Balance	3,162	7,597
Contractual Unpaid Principal Balance	14,619	17,426
Related Allowance	201	307
Loans without related allowance, Average Investment in Impaired Loans	10,399	7,369
Loans with related allowance, Average Investment in Impaired Loans	4,088	7,594
Average Investment in Impaired Loans	14,487	14,963
Loans without related allowance, Interest Income Recognized	157	188
Loans with related allowance, Interest Income Recognized	128	317
Interest Income Recognized	285	505
Commercial, industrial and other
Financing Receivable, Impaired [Line Items]
Loans without related allowance, Recorded Investment in Impaired Loans	628	1,151
Loans with related allowance, Recorded Investment in Impaired Loans	121	209
Recorded Investment in Impaired Loans	749	1,360
Loans without related allowance, Contractual Unpaid Principal Balance	617	1,449
Loans with related allowance, Contractual Unpaid Principal Balance	121	209
Contractual Unpaid Principal Balance	738	1,658
Related Allowance	6	7
Loans without related allowance, Average Investment in Impaired Loans	1,341	1,834
Loans with related allowance, Average Investment in Impaired Loans	121	209
Average Investment in Impaired Loans	1,462	2,043
Loans without related allowance, Interest Income Recognized	13	19
Loans with related allowance, Interest Income Recognized	5	12
Interest Income Recognized	18	31
Equipment finance
Financing Receivable, Impaired [Line Items]
Loans without related allowance, Recorded Investment in Impaired Loans	0	301
Loans with related allowance, Recorded Investment in Impaired Loans	25	30
Recorded Investment in Impaired Loans	25	331
Loans without related allowance, Contractual Unpaid Principal Balance	0	597
Loans with related allowance, Contractual Unpaid Principal Balance	25	30
Contractual Unpaid Principal Balance	25	627
Related Allowance	11	14
Loans without related allowance, Average Investment in Impaired Loans	0	376
Loans with related allowance, Average Investment in Impaired Loans	25	19
Average Investment in Impaired Loans	25	395
Loans without related allowance, Interest Income Recognized	0	0
Loans with related allowance, Interest Income Recognized	2	0
Interest Income Recognized	2	0
Real estate - residential mortgage
Financing Receivable, Impaired [Line Items]
Loans without related allowance, Recorded Investment in Impaired Loans	1,678	0
Loans with related allowance, Recorded Investment in Impaired Loans	686	730
Recorded Investment in Impaired Loans	2,364	730
Loans without related allowance, Contractual Unpaid Principal Balance	1,672	0
Loans with related allowance, Contractual Unpaid Principal Balance	855	884
Contractual Unpaid Principal Balance	2,527	884
Related Allowance	3	4
Loans without related allowance, Average Investment in Impaired Loans	75	242
Loans with related allowance, Average Investment in Impaired Loans	698	745
Average Investment in Impaired Loans	773	987
Loans without related allowance, Interest Income Recognized	0	4
Loans with related allowance, Interest Income Recognized	15	20
Interest Income Recognized	15	24
Real estate - construction
Financing Receivable, Impaired [Line Items]
Loans without related allowance, Recorded Investment in Impaired Loans	0	0
Loans with related allowance, Recorded Investment in Impaired Loans	0	0
Recorded Investment in Impaired Loans	0	0
Loans without related allowance, Contractual Unpaid Principal Balance	0	0
Loans with related allowance, Contractual Unpaid Principal Balance	0	0
Contractual Unpaid Principal Balance	0	0
Related Allowance	0	0
Loans without related allowance, Average Investment in Impaired Loans	0	726
Loans with related allowance, Average Investment in Impaired Loans	0	0
Average Investment in Impaired Loans	0	726
Loans without related allowance, Interest Income Recognized	0	0
Loans with related allowance, Interest Income Recognized	0	0
Interest Income Recognized	0	0
Home equity and consumer
Financing Receivable, Impaired [Line Items]
Loans without related allowance, Recorded Investment in Impaired Loans	0	0
Loans with related allowance, Recorded Investment in Impaired Loans	695	727
Recorded Investment in Impaired Loans	695	727
Loans without related allowance, Contractual Unpaid Principal Balance	0	0
Loans with related allowance, Contractual Unpaid Principal Balance	788	765
Contractual Unpaid Principal Balance	788	765
Related Allowance	5	6
Loans without related allowance, Average Investment in Impaired Loans	0	0
Loans with related allowance, Average Investment in Impaired Loans	713	898
Average Investment in Impaired Loans	713	898
Loans without related allowance, Interest Income Recognized	0	0
Loans with related allowance, Interest Income Recognized	22	32
Interest Income Recognized	$ 22	$ 32

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
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