Loans and Allowance for Loan Losses - Schedule of Activity in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 55,461	$ 50,381
Charge-offs	(2,892)	(2,685)
Recoveries	1,947	2,305
Provision	1,043	380
Ending balance	55,559	50,381
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	21,742	19,246
Charge-offs	(160)	(245)
Recoveries	375	511
Provision	(1,551)	79
Ending balance	20,406	19,591
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	23,470	21,436
Charge-offs	(235)	(3)
Recoveries	570	484
Provision	1,364	(1,121)
Ending balance	25,169	20,796
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	2,277	1,763
Charge-offs	(178)	(362)
Recoveries	72	148
Provision	131	214
Ending balance	2,302	1,763
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	7,972	7,936
Charge-offs	(2,319)	(2,075)
Recoveries	930	1,162
Provision	1,099	1,208
Ending balance	$ 7,682	$ 8,231

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of expense related to estimated loss from loan and lease transactions.

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