Loans and Allowance - Changes in Allowance for Loan Losses by Loan Segment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Allowance for loan losses:
Beginning balance	$ 80,284	$ 80,552
Provision for losses	19,752	1,200
Recoveries on loans	673	1,005
Loans charged off	(1,255)	(1,855)
Ending balance	99,454	80,902
Commercial
Allowance for loan losses:
Beginning balance	32,902	32,657
Provision for losses	5,701	236
Recoveries on loans	443	542
Loans charged off	(615)	(366)
Ending balance	38,431	33,069
Commercial Real Estate
Allowance for loan losses:
Beginning balance	28,778	29,609
Provision for losses	9,194	769
Recoveries on loans	118	245
Loans charged off	(183)	(1,189)
Ending balance	37,907	29,434
Consumer
Allowance for loan losses:
Beginning balance	4,035	3,964
Provision for losses	1,924	105
Recoveries on loans	42	118
Loans charged off	(249)	(161)
Ending balance	5,752	4,026
Residential
Allowance for loan losses:
Beginning balance	14,569	14,322
Provision for losses	2,933	90
Recoveries on loans	70	100
Loans charged off	(208)	(139)
Ending balance	$ 17,364	$ 14,373

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

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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- Definition

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.

+ References

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- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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