Loans and Allowance - Changes in Allowance for Loan Losses by Loan Segment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Allowance for loan losses:
Beginning balance	$ 81,274	$ 77,543	$ 80,552	$ 75,032
Provision for losses	600	1,400	2,300	5,563
Recoveries on loans	596	1,175	3,035	5,066
Loans charged off	(1,899)	(1,712)	(5,316)	(7,255)
Ending balance	80,571	78,406	80,571	78,406
Commercial
Allowance for loan losses:
Beginning balance	33,202	31,467	32,657	30,420
Provision for losses	130	256	466	1,567
Recoveries on loans	149	658	1,035	2,060
Loans charged off	(480)	(313)	(1,157)	(1,979)
Ending balance	33,001	32,068	33,001	32,068
Commercial Real Estate
Allowance for loan losses:
Beginning balance	29,531	27,731	29,609	27,343
Provision for losses	370	410	1,459	1,448
Recoveries on loans	143	306	1,166	1,858
Loans charged off	(1,078)	(501)	(3,268)	(2,703)
Ending balance	28,966	27,946	28,966	27,946
Consumer
Allowance for loan losses:
Beginning balance	4,070	3,921	3,964	3,732
Provision for losses	40	159	181	493
Recoveries on loans	105	46	323	233
Loans charged off	(109)	(194)	(362)	(526)
Ending balance	4,106	3,932	4,106	3,932
Residential
Allowance for loan losses:
Beginning balance	14,471	14,424	14,322	13,537
Provision for losses	60	575	194	2,055
Recoveries on loans	199	165	511	915
Loans charged off	(232)	(704)	(529)	(2,047)
Ending balance	$ 14,498	$ 14,460	$ 14,498	$ 14,460

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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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.

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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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