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Allowance for Credit Losses - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended
	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Reserve for concentration risk			$ 5,435
Reserves on individually evaluated loans			471
Allowance for credit loss		$ 30,616	85,941	$ 57,911	$ 91,847
Cumulative effect adjustment, decrease in retained earnings		906,570	942,539	866,426	925,114
Threshold for loan analysis			1,000
ASU 2016-13
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit loss	$ 18,913
Reclassification of financing receivable	$ 481
Retained Earnings
Loans and Leases Receivable Disclosure [Line Items]
Cumulative effect adjustment, decrease in retained earnings		367,794	408,211	356,935	$ 381,999
Impact of CECL Adoption
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit loss		18,913
Tax portion of cumulative effect adjustment		5,449
Cumulative effect adjustment, decrease in retained earnings		(12,983)
Impact of CECL Adoption | Retained Earnings
Loans and Leases Receivable Disclosure [Line Items]
Cumulative effect adjustment, decrease in retained earnings		$ (12,983)
Financial Asset Originated
Loans and Leases Receivable Disclosure [Line Items]
Interest lost on nonaccrual loans			536	431
Interest income on nonaccrual loans			$ 17	$ 47

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Financing Receivable, Allowance For Credit Losses, Individually Evaluated For Impairment, Increase (Decrease)

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of cumulative tax effect on beginning retained earnings from change in accounting principle.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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