Loans (Narrative) (Details)	3 Months Ended			9 Months Ended
	Sep. 30, 2017 USD ($) grade		Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) grade		Sep. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)		Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 20,166,091,000	[1]	$ 19,555,787,000	$ 20,166,091,000	[1]	$ 19,555,787,000		$ 19,589,520,000	[1]
Allowance - purchased credit impaired loans	3,135,000		1,166,000	3,135,000		1,166,000		700,000
Provision expense for Loan and Lease Losses	2,600,000		300,000	2,400,000
Troubled debt restructurings loans	241,600,000			241,600,000				285,200,000
Less: Allowance for loan losses	194,867,000		201,557,000	194,867,000		201,557,000	$ 197,257,000	202,068,000		$ 199,807,000	$ 210,242,000
Average balance of impaired loans	260,083,000		312,649,000	275,227,000		313,034,000
Interest income recognized on impaired loan	1,692,000		1,760,000	5,104,000		4,898,000
Provision for loan losses	0		4,000,000	(3,000,000)		11,000,000
Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	15,042,859,000			15,042,859,000				14,283,610,000
Allowance - purchased credit impaired loans	2,781,000			2,781,000				319,000
Less: Allowance for loan losses	127,888,000			127,888,000				123,250,000
Permanent Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	403,082,000		436,100,000	403,082,000		436,100,000		423,125,000
Allowance - purchased credit impaired loans	0		0	0		0
Less: Allowance for loan losses	$ 15,719,000		16,589,000	$ 15,719,000		16,589,000	16,398,000	16,289,000		17,600,000	18,947,000
TDR, reduction of interest rate by increment, basis points	0.25%			0.25%
TDRS Maturities				40 years
Modified interest rate increase	1.00%			1.00%
Provision for loan losses	$ (1,048,000)		(877,000)	$ (1,004,000)		(3,026,000)
Loans Held-For-Sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings loans	63,200,000			$ 63,200,000				69,300,000
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage				24.00%
Consumer Real Estate Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,369,717,000		4,578,371,000	$ 4,369,717,000		4,578,371,000		4,523,752,000
Concentration risk, percentage				22.00%
Allowance - purchased credit impaired loans	354,000		333,000	$ 354,000		333,000
Less: Allowance for loan losses	40,939,000		53,235,000	$ 40,939,000		53,235,000	46,069,000	50,357,000		59,081,000	80,614,000
TDRS Maturities				30 years
Provision for loan losses	(7,717,000)		(7,078,000)	$ (15,024,000)		(26,920,000)
Allowance For TDRs To Recorded Investment Of TDRs
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan loss reserves	$ 38,600,000			$ 38,600,000				$ 44,900,000
Ratio of the allowance for loan losses to loans	16.00%			16.00%				16.00%
Loans To Mortgage Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 1,966,155,000			$ 1,966,155,000				$ 2,045,189,000
Loans To Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 1,966,155,000			$ 1,966,155,000				2,045,189,000
Percentage of commercial & industrial loan portfolio	15.00%			15.00%
Percentage contributed in total loan	10.00%			10.00%
Credit Card And Other Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 350,433,000		357,423,000	$ 350,433,000		357,423,000		359,033,000
Allowance - purchased credit impaired loans	0		0	0		0
Less: Allowance for loan losses	10,321,000		12,447,000	10,321,000		12,447,000	$ 11,941,000	12,172,000		$ 11,890,000	$ 11,885,000
Provision for loan losses	882,000		$ 3,240,000	5,698,000		$ 8,217,000
Credit Card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 194,049,000			$ 194,049,000				191,651,000
Credit card workout program, granted rate reduction	0.00%			0.00%
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%
Restricted And Secured Consumer Real Estate Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 26,200,000			$ 26,200,000				35,900,000
Finance And Insurance Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 2,800,000,000			$ 2,800,000,000
Percentage of commercial & industrial loan portfolio	22.00%			22.00%
Percentage contributed in total loan	14.00%			14.00%
Finance Insurance And Loans To Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of commercial & industrial loan portfolio	37.00%			37.00%
TRUPs
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 307,333,000			$ 307,333,000				307,445,000	[2]
Loan loss reserves	25,500,000			25,500,000				25,500,000
TRUPs | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	307,333,000			307,333,000				307,445,000	[3]
Loan loss reserves	$ 25,500,000			$ 25,500,000				25,500,000
Maximum | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period				12 months
Maximum | Permanent Mortgage Portfolio Segment
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
Maximum | Heloc And Real Estate Installment Classes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate time period				5 years
Minimum | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period				6 months
Minimum | Permanent Mortgage Portfolio Segment
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
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
Pass | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades | grade	12			12
Pass | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades | grade	1			1
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
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
Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades | grade	16			16
Loss | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades | grade	16			16
PD Grade 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lowest expected default probability | grade	1			1
PD Grade 1 | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for loan losses	$ 81,000			$ 81,000				77,000
PD Grade 12 | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for loan losses	7,065,000			7,065,000				6,377,000
PD Grade 13 | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for loan losses	6,927,000			6,927,000				$ 4,225,000
PD Grade 13 | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 500,000			$ 500,000
LGD Grade 1 | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades | grade	1			1
LGD Grade 12 | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades | grade	12			12
Loan Reassessed | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loans	$ 1,000,000			$ 1,000,000

[1] September 30, 2017 and December 31, 2016 include $24.8 million and $28.5 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate properties in process of foreclosure.

[2] TRUPS is presented net of the valuation allowance of $25.5 million.

[3] Balances as of September 30, 2017 and December 31, 2016, presented net of a $25.5 million valuation allowance. Based on the underlying structure of the notes, the highest possible internal grade is “13”.