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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		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	$ 64,568	$ 64,959	$ 63,018	$ 66,359
Charge-offs	(6,825)	(6,374)	(19,251)	(17,422)
Recoveries	1,537	1,308	4,635	3,416
Provision	6,388	4,966	17,266	12,506
Balance, end of period	65,668	64,859	65,668	64,859
Allowance for loan losses for acquired loan portfolio	700	1,900	700	1,900
Provision expense and net charge-offs related to acquired loans	100	500	400	1,200
Commercial Loans [Member]
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	25,222	28,326	25,545	32,433
Charge-offs	(637)	(1,333)	(1,723)	(2,715)
Recoveries	512	258	1,616	772
Provision	1,514	(2,800)	1,173	(6,039)
Balance, end of period	26,611	24,451	26,611	24,451
Consumer Loans [Member]
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	31,471	28,314	29,253	26,720
Charge-offs	(6,046)	(4,530)	(16,409)	(13,183)
Recoveries	898	889	2,779	2,334
Provision	6,078	7,333	16,778	16,135
Balance, end of period	32,401	32,006	32,401	32,006
Residential Real Estate Mortgages [Member]
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	7,875	8,281	7,960	7,130
Charge-offs	(142)	(511)	(1,119)	(1,524)
Recoveries	127	161	240	310
Provision	(1,481)	51	(702)	2,066
Balance, end of period	6,379	7,982	6,379	7,982
Unallocated [Member]
Changes in allowance for loan losses by portfolio segment [Roll Forward]
Balance, beginning of period	0	38	260	76
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	277	382	17	344
Balance, end of period	$ 277	$ 420	$ 277	$ 420

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

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

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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 to estimated loss from loan and lease transactions.

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