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Allowance for Loan Losses and Credit Quality of Loans, Allowance for Loan Losses by Portfolio Segments (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	$ 65,200	$ 63,018	$ 63,018
Charge-offs	(8,394)	(6,559)
Recoveries	1,515	1,761
Provision	7,379	6,098
Balance, end of period	65,700	64,318	65,200
Allowance for loan losses for acquired loan portfolio	0		700
Provision expense and net charge-offs related to acquired loans	400		100
Commercial Loans [Member]
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	25,444	25,545	25,545
Charge-offs	(1,294)	(437)
Recoveries	447	765
Provision	130	(574)
Balance, end of period	24,727	25,299	25,444
Consumer Loans [Member]
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	33,375	29,253	29,253
Charge-offs	(6,502)	(5,413)
Recoveries	1,035	974
Provision	6,861	6,221
Balance, end of period	34,769	31,035	33,375
Residential Real Estate Mortgages [Member]
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	6,381	7,960	7,960
Charge-offs	(598)	(709)
Recoveries	33	22
Provision	388	711
Balance, end of period	6,204	7,984	6,381
Unallocated [Member]
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	0	260	260
Charge-offs	0	0
Recoveries	0	0
Provision	0	(260)
Balance, end of period	$ 0	$ 0	$ 0

X

- Definition

Reduction to the allowance for credit losses related to acquired financing receivables deemed uncollectible and the sum of the periodic provision charged to earnings, based on an assessment of uncollectibility from the counterparty on account of acquired loan, lease or other credit losses, to reduce these accounts to the amount that approximates their net realizable value.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(4)
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- Definition

Amount of addition to allowance reserve for credit loss arising from purchase of loan and lease portfolios.

+ References

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-Name Accounting Standards Codification
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- Definition

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.

+ References

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-Publisher FASB
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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.

+ References

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

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