Credit Quality - Schedule of Nonaccrual Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccruals	$ 127,824	$ 127,824	$ 111,596
With No Related Allowance for Credit Losses	94,701	94,701
Recorded Investment > 90 Days & Accruing	11,150	11,150	9,494
Interest Income Recognized	22	37
Commercial Real Estate [Member] \| Owner-Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccruals	31,780	31,780	10,665
With No Related Allowance for Credit Losses	26,723	26,723
Recorded Investment > 90 Days & Accruing	1,419	1,419	544
Interest Income Recognized	17	32
Commercial Real Estate [Member] \| Nonowner-Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccruals	22,506	22,506	15,658
With No Related Allowance for Credit Losses	19,882	19,882
Recorded Investment > 90 Days & Accruing	859	859	471
Interest Income Recognized	1	1
Other Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccruals	42,679	42,679	50,873
With No Related Allowance for Credit Losses	18,909	18,909
Recorded Investment > 90 Days & Accruing	777	777	668
Interest Income Recognized	1	1
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccruals	23,649	23,649	18,087
With No Related Allowance for Credit Losses	22,022	22,022
Recorded Investment > 90 Days & Accruing	6,234	6,234	6,256
Interest Income Recognized	3	3
Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccruals	6,804	6,804	16,043
With No Related Allowance for Credit Losses	6,759	6,759
Recorded Investment > 90 Days & Accruing	84	84
Interest Income Recognized	0	0
Consumer [Member] \| Bankcard [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccruals	0	0	0
With No Related Allowance for Credit Losses	0	0
Recorded Investment > 90 Days & Accruing	160	160	218
Interest Income Recognized	0	0
Consumer [Member] \| Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccruals	406	406	270
With No Related Allowance for Credit Losses	406	406
Recorded Investment > 90 Days & Accruing	1,617	1,617	$ 1,337
Interest Income Recognized	$ 0	$ 0

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