Loans and the Allowance for Credit Losses - Allowance for Credit Losses and Recorded Investments in Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	$ 124
Allowance for loans collectively evaluated for impairment	52,305	$ 48,948
Allowance for loan commitments	874	741	$ 574	$ 571
Total allowance for credit losses	53,303	49,689	45,858	44,245
Individually evaluated for impairment	21,017
Collectively evaluated for impairment	10,232,455	7,646,540
Acquired with deteriorated credit quality	14,513	9,741
Total loans	10,267,985	7,656,281
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	4,949	4,039
Allowance for loan commitments	235	169	119	151
Total allowance for credit losses	5,184	4,208	3,236	4,499
Collectively evaluated for impairment	777,033	527,737
Acquired with deteriorated credit quality	118	335
Total loans	777,151	528,072
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	93
Allowance for loans collectively evaluated for impairment	20,200	20,848
Allowance for loan commitments	22	33	26	17
Total allowance for credit losses	20,315	20,881	21,192	18,645
Individually evaluated for impairment	3,907
Collectively evaluated for impairment	4,935,383	3,319,672
Acquired with deteriorated credit quality	8,567	5,951
Total loans	4,947,857	3,325,623
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	10
Allowance for loans collectively evaluated for impairment	14,106	12,114
Allowance for loan commitments	311	262	173	188
Total allowance for credit losses	14,427	12,376	9,587	8,600
Individually evaluated for impairment	11,961
Collectively evaluated for impairment	1,631,855	1,264,560
Acquired with deteriorated credit quality	883	900
Total loans	1,644,699	1,265,460
Deposit Overdraft [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	1,387	972
Total allowance for credit losses	1,387	972	821	760
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	14
Allowance for loans collectively evaluated for impairment	4,297	3,822
Allowance for loan commitments	15	12	7	9
Total allowance for credit losses	4,326	3,834	3,213	4,115
Individually evaluated for impairment	4,392
Collectively evaluated for impairment	1,865,151	1,609,177
Acquired with deteriorated credit quality	4,104	2,430
Total loans	1,873,647	1,611,607
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	1
Allowance for loans collectively evaluated for impairment	2,950	2,797
Allowance for loan commitments	41	39	37	44
Total allowance for credit losses	2,992	2,836	3,100	4,042
Individually evaluated for impairment	53
Collectively evaluated for impairment	374,812	326,063
Acquired with deteriorated credit quality	88	125
Total loans	374,953	326,188
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	6
Allowance for loans collectively evaluated for impairment	4,416	4,356
Allowance for loan commitments	250	226	212	162
Total allowance for credit losses	4,672	4,582	$ 4,709	$ 3,584
Individually evaluated for impairment	704
Collectively evaluated for impairment	648,221	599,331
Acquired with deteriorated credit quality	753
Total loans	$ 649,678	$ 599,331

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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