Amount, after recoveries, of loans and leases that have been written-off.

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Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity).

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Amount of expense (reversal of expense) for expected credit loss on investment in debt security measured at amortized cost (held-to-maturity).

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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, before troubled debt restructuring, of financing receivable to be modified.

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Amount of financing receivable on nonaccrual status with no allowance for credit loss.

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

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Allowance for Credit Losses (Allowance for Credit Losses Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Nonaccrual loans with no related allowance for credit losses	$ 82,200		$ 82,200
Loans reasonably expected to be modified into TDRs			3,700
Allowance for loan losses	388,908	$ 163,273	388,908	$ 163,273	$ 373,109		$ 158,461	$ 161,901	$ 154,164
Provision for credit losses	25,028	10,834	213,051	46,038
Loan net charge-offs	9,300		30,000
Allowance for held-to-maturity securities losses	63	0	63	0			0
Held-to-maturity securities, provision (reversal) for credit losses	(2)		(11)
Cumulative effect adjustment from the adoption of ASU 2016-13
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses							47,344
Allowance for held-to-maturity securities losses						$ 74
Loans acquired with deteriorated credit quality
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses		473		473
Loans acquired with deteriorated credit quality \| Cumulative effect adjustment from the adoption of ASU 2016-13
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses						11,000
Loans acquired without deteriorated credit quality \| Cumulative effect adjustment from the adoption of ASU 2016-13
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses						3,200
Unfunded lending-related commitments
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses	62,949	1,510	62,949	1,510			1,633
Unfunded lending-related commitments \| Cumulative effect adjustment from the adoption of ASU 2016-13
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses						33,200
Loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses	$ 325,959	$ 161,763	$ 325,959	$ 161,763			$ 156,828
Loans \| Cumulative effect adjustment from the adoption of ASU 2016-13
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses						$ 14,200