Loans and Allowance - Changes in Allowance for Loan Losses by Loan Segment (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Allowance for loan losses:
Beginning balance	$ 80,902	$ 76,420	$ 80,552	$ 75,032
Provision for losses	500	1,663	1,700	4,163
Recoveries on loans	1,434	3,190	2,439	3,891
Loans charged off	(1,562)	(3,730)	(3,417)	(5,543)
Ending balance	81,274	77,543	81,274	77,543
Commercial
Allowance for loan losses:
Beginning balance	33,069	30,770	32,657	30,420
Provision for losses	100	471	336	1,311
Recoveries on loans	344	1,283	886	1,402
Loans charged off	(311)	(1,057)	(677)	(1,666)
Ending balance	33,202	31,467	33,202	31,467
Commercial Real Estate
Allowance for loan losses:
Beginning balance	29,434	27,705	29,609	27,343
Provision for losses	320	954	1,089	1,038
Recoveries on loans	778	1,213	1,023	1,552
Loans charged off	(1,001)	(2,141)	(2,190)	(2,202)
Ending balance	29,531	27,731	29,531	27,731
Consumer
Allowance for loan losses:
Beginning balance	4,026	3,896	3,964	3,732
Provision for losses	36	60	141	334
Recoveries on loans	100	98	218	187
Loans charged off	(92)	(133)	(253)	(332)
Ending balance	4,070	3,921	4,070	3,921
Residential
Allowance for loan losses:
Beginning balance	14,373	14,049	14,322	13,537
Provision for losses	44	178	134	1,480
Recoveries on loans	212	596	312	750
Loans charged off	(158)	(399)	(297)	(1,343)
Ending balance	$ 14,471	$ 14,424	$ 14,471	$ 14,424

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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