Loans and Other Real Estate - Impaired Loans with and without Specific Allowances (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Recorded Investment in Impaired Loans	$ 17,385	$ 19,702
Contractual Unpaid Principal Balance	18,258	21,360
Related Allowance	244	338
Average Investment in Impaired Loans	18,220	20,012
Interest Income Recognized	266	592
Commercial, secured by real estate
Financing Receivable, Impaired [Line Items]
Loans without related allowance, Recorded Investment in Impaired Loans	11,465	9,284
Loans with related allowance, Recorded Investment in Impaired Loans	3,758	7,270
Recorded Investment in Impaired Loans	15,223	16,554
Loans without related allowance, Contractual Unpaid Principal Balance	11,863	9,829
Loans with related allowance, Contractual Unpaid Principal Balance	4,033	7,597
Contractual Unpaid Principal Balance	15,896	17,426
Related Allowance	219	307
Loans without related allowance, Average Investment in Impaired Loans	10,074	7,369
Loans with related allowance, Average Investment in Impaired Loans	5,201	7,594
Average Investment in Impaired Loans	15,275	14,963
Loans without related allowance, Interest Income Recognized	103	188
Loans with related allowance, Interest Income Recognized	112	317
Interest Income Recognized	215	505
Commercial, industrial and other
Financing Receivable, Impaired [Line Items]
Loans without related allowance, Recorded Investment in Impaired Loans	644	1,151
Loans with related allowance, Recorded Investment in Impaired Loans	128	209
Recorded Investment in Impaired Loans	772	1,360
Loans without related allowance, Contractual Unpaid Principal Balance	633	1,449
Loans with related allowance, Contractual Unpaid Principal Balance	128	209
Contractual Unpaid Principal Balance	761	1,658
Related Allowance	7	7
Loans without related allowance, Average Investment in Impaired Loans	1,146	1,834
Loans with related allowance, Average Investment in Impaired Loans	128	209
Average Investment in Impaired Loans	1,274	2,043
Loans without related allowance, Interest Income Recognized	9	19
Loans with related allowance, Interest Income Recognized	4	12
Interest Income Recognized	13	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	23	30
Recorded Investment in Impaired Loans	23	331
Loans without related allowance, Contractual Unpaid Principal Balance	0	597
Loans with related allowance, Contractual Unpaid Principal Balance	23	30
Contractual Unpaid Principal Balance	23	627
Related Allowance	10	14
Loans without related allowance, Average Investment in Impaired Loans	255	376
Loans with related allowance, Average Investment in Impaired Loans	28	19
Average Investment in Impaired Loans	283	395
Loans without related allowance, Interest Income Recognized	0	0
Loans with related allowance, Interest Income Recognized	13	0
Interest Income Recognized	13	0
Real estate - residential mortgage
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	700	730
Recorded Investment in Impaired Loans	700	730
Loans without related allowance, Contractual Unpaid Principal Balance	0	0
Loans with related allowance, Contractual Unpaid Principal Balance	865	884
Contractual Unpaid Principal Balance	865	884
Related Allowance	3	4
Loans without related allowance, Average Investment in Impaired Loans	0	242
Loans with related allowance, Average Investment in Impaired Loans	708	745
Average Investment in Impaired Loans	708	987
Loans without related allowance, Interest Income Recognized	0	4
Loans with related allowance, Interest Income Recognized	10	20
Interest Income Recognized	10	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	667	727
Recorded Investment in Impaired Loans	667	727
Loans without related allowance, Contractual Unpaid Principal Balance	0	0
Loans with related allowance, Contractual Unpaid Principal Balance	713	765
Contractual Unpaid Principal Balance	713	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	680	898
Average Investment in Impaired Loans	680	898
Loans without related allowance, Interest Income Recognized	0	0
Loans with related allowance, Interest Income Recognized	15	32
Interest Income Recognized	$ 15	$ 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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