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The PD grade that has the lowest expected default probability.

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Modified Interest Rate Time Period, Maximum.

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For credit card hardship program, time range that payment reductions may be granted for modified loans classified as TDRs.

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Bank-related and TRUPs loans divided by total loan portfolio.

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Percentage of Commercial And Industrial Loan Portfolio

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Ratio Of The Allowance For Loan Losses To Loans

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Maximum maturities for TDRs.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reserve for loans impairments recorded after acquisition as a result of current information and events which result in it being probable that estimated cash flows will be less than previously expected or because actual cash flows are less than cash flows previously expected. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Amount of expense related to loan loss not accounted for as debt securities, with evidence of deterioration of credit quality.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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A valuation allowance for financing receivables that are expected to be uncollectible.

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Amount, before allowance and fees, of loans and leases receivable. Excludes loans and leases covered under loss sharing agreements.

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Loans (Narrative) (Details)	3 Months Ended		6 Months Ended
Loans (Narrative) (Details)	Jun. 30, 2018 USD ($) grade	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) grade	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance - purchased credit-impaired loans	$ 3,007,000	$ 530,000	$ 3,007,000	$ 530,000	$ 3,200,000
Provision expense (credit) for loan and lease losses	1,800,000	(100,000)	2,600,000	(200,000)
Financing receivable, modifications, recorded investment	$ 217,600,000		$ 217,600,000		234,400,000
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage			24.00%
Heloc And Real Estate Installment Classes
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR, reduction of interest rate by increment, basis points	0.25%		0.25%
Modified interest rate increase	2.00%		2.00%
Permanent Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance - purchased credit-impaired loans	$ 0	0	$ 0	0
TDR, reduction of interest rate by increment, basis points	0.25%		0.25%
Modified interest rate increase	1.00%		1.00%
TDRS maturities			40 years
Consumer Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage			23.00%
Allowance - purchased credit-impaired loans	$ 640,000	$ 384,000	$ 640,000	$ 384,000
TDRS maturities			30 years
Credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit card workout program, granted rate reduction	0.00%		0.00%
Allowance For TDRs To Recorded Investment Of TDRs
Accounts, Notes, Loans and Financing Receivable [Line Items]
Valuation allowance	$ 31,500,000		$ 31,500,000		$ 37,300,000
Ratio of the allowance for loan losses to loans	14.00%		14.00%		16.00%
Loans Held-For-Sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, modifications, recorded investment	$ 60,500,000		$ 60,500,000		$ 63,200,000
Minimum \| Heloc And Real Estate Installment Classes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate	1.00%		1.00%
Modified interest rate time period			5 years
Minimum \| Permanent Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate	2.00%		2.00%
Modified interest rate time period			5 years
Minimum \| Credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment reductions, time period			6 months
Maximum \| Heloc And Real Estate Installment Classes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate time period			5 years
Maximum \| Permanent Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate time period			5 years
Maximum \| Credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment reductions, time period			1 year
Credit card workout program, term extension			5 years
Commercial Loan P D Grade One
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lowest expected default probability \| grade	1		1
Pass \| Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	1		1
Pass \| Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	12		12
Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	13		13
Special Mention \| Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	13		13
Unlikely to be Collected Financing Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	16		16
Unlikely to be Collected Financing Receivable \| Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	16		16
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	14		14
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	15		15
Loan Reassessed \| Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 1,000,000		$ 1,000,000
Commercial Loan P D Grade Thirteen \| Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 500,000		$ 500,000
Commercial Loan L G D Grade One \| Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	1		1
Commercial Loan L G D Grade Twelve \| Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades \| grade	12		12
Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 20,575,101,000		$ 20,575,101,000		20,271,968,000
Allowance - purchased credit-impaired loans	2,280,000		2,280,000		2,813,000
Commercial Portfolio Segment \| Finance And Insurance Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 2,800,000,000		$ 2,800,000,000
Percentage of commercial & industrial loan portfolio	17.00%		17.00%
Percentage contributed in total loan	10.00%		10.00%
Commercial Portfolio Segment \| Loans to Mortgage Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 2,354,836,000		$ 2,354,836,000		$ 2,099,961,000
Percentage of commercial & industrial loan portfolio	14.00%		14.00%
Percentage contributed in total loan	9.00%		9.00%
Commercial Portfolio Segment \| Finance Insurance And Loans To Mortgage Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of commercial & industrial loan portfolio	31.00%		31.00%
Commercial Portfolio Segment \| Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period			6 months
Commercial Portfolio Segment \| Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period			12 months