Preparation of Interim Financial Statements (Details) $ in Thousands	Jan. 01, 2020 USD ($)	Sep. 30, 2021 USD ($) financial_center	Dec. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Number of financial centers \| financial_center		185
Allowance for credit loss		$ 202,508	$ 238,050
Unfunded commitments, allowance for credit loss		22,400	22,400
Cumulative effect on retained earnings		$ 1,065,566	$ 901,006
Cumulative Effect, Period of Adoption, Adjustment
Lessee, Lease, Description [Line Items]
Allowance for credit loss	$ 151,400
Unfunded commitments, allowance for credit loss	24,000
Debt securities, allowance for credit loss	742
Cumulative effect on retained earnings	128,100
Purchased with credit deterioration, allowance for credit loss	$ 5,400

Debt Securities, Allowance for Credit Loss

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- Definition

Represents the entity's number of financial centers as of the balance sheet date.

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Amount of allowance for credit loss at acquisition date of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration.

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Amount excluding accrued interest, of allowance for credit loss on financing receivable.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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