Allowance for Loan and Lease Losses (Allocation of Allowance for Loan and Lease Losses) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans And Leases, Growth	$ 907,800,000
Reclassification	0	7,368,000	[1]	0
Unpaid principal balance	2,057,691,000	1,833,955,000
Financing Receivable, Individually Evaluated for Impairment	119,593,000	132,146,000
Noncommercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	7,368,000
Noncommercial | Non-specific
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	(15,772,000)
Commercial Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Credit Losses, Change During Period	1,700,000
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		7,368,000	[1]
Unpaid principal balance	133,466,000	145,485,000
ALLL for loans and leases individually evaluated for impairment	15,717,000	10,161,000
Financing Receivable, Individually Evaluated for Impairment	119,593,000	132,146,000
Financing Receivable, Individually Evaluated for Impairment, Change During Period	(12,600,000)
Average balance	127,421,000	151,330,000		158,426,000
Interest income recognized	5,427,000	7,817,000		6,735,000
Financing Receivable, Collectively Evaluated for Impairment, Change During Period	5,490,000,000
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		5,141,000	[1]
Unpaid principal balance	6,945,000	7,306,000
ALLL for loans and leases individually evaluated for impairment	92,000	103,000
Financing Receivable, Individually Evaluated for Impairment	1,620,000	2,272,000
Average balance	1,689,000	6,414,000		22,493,000
Interest income recognized	83,000	270,000		399,000
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		27,421,000	[1]
Unpaid principal balance	87,702,000	103,522,000
ALLL for loans and leases individually evaluated for impairment	8,610,000	6,873,000
Financing Receivable, Individually Evaluated for Impairment	82,803,000	97,111,000
Average balance	86,250,000	105,628,000		96,082,000
Interest income recognized	3,698,000	5,702,000		4,630,000
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		(815,000)	[1]
Unpaid principal balance	913,000	2,279,000
ALLL for loans and leases individually evaluated for impairment	112,000	209,000
Financing Receivable, Individually Evaluated for Impairment	584,000	1,878,000
Average balance	2,125,000	2,658,000		2,690,000
Interest income recognized	80,000	144,000		142,000
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		7,551,000	[1]
Unpaid principal balance	12,197,000	10,393,000
ALLL for loans and leases individually evaluated for impairment	1,743,000	771,000
Financing Receivable, Individually Evaluated for Impairment	11,040,000	9,300,000
Average balance	13,433,000	12,772,000		13,658,000
Interest income recognized	580,000	642,000		788,000
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		(253,000)	[1]
Unpaid principal balance	623,000	188,000
ALLL for loans and leases individually evaluated for impairment	150,000	54,000
Financing Receivable, Individually Evaluated for Impairment	623,000	188,000
Average balance	774,000	350,000		497,000
Interest income recognized	44,000	22,000		37,000
Non-PCI Loans | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		(1,288,000)	[1]
Unpaid principal balance	2,000,000
ALLL for loans and leases individually evaluated for impairment	1,972,000	0
Financing Receivable, Individually Evaluated for Impairment	2,000,000	0
Average balance	528,000	0		424,000
Interest income recognized	29,000	0		23,000
Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		5,717,000	[1]
Unpaid principal balance	15,746,000	15,939,000
ALLL for loans and leases individually evaluated for impairment	1,360,000	1,586,000
Financing Receivable, Individually Evaluated for Impairment	14,913,000	15,539,000
Average balance	15,487,000	15,470,000		14,951,000
Interest income recognized	593,000	444,000		586,000
Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		(478,000)	[1]
Unpaid principal balance	1,340,000	1,108,000
ALLL for loans and leases individually evaluated for impairment	71,000	72,000
Financing Receivable, Individually Evaluated for Impairment	1,340,000	1,108,000
Average balance	1,678,000	958,000		2,850,000
Interest income recognized	98,000	55,000		41,000
Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		(9,838,000)	[1]
Unpaid principal balance	4,933,000	3,596,000
ALLL for loans and leases individually evaluated for impairment	1,052,000	372,000
Financing Receivable, Individually Evaluated for Impairment	3,675,000	3,596,000
Average balance	3,922,000	5,653,000		2,931,000
Interest income recognized	134,000	485,000		68,000
Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		(10,018,000)	[1]
Unpaid principal balance	1,067,000	1,154,000
ALLL for loans and leases individually evaluated for impairment	555,000	121,000
Financing Receivable, Individually Evaluated for Impairment	995,000	1,154,000
Average balance	1,535,000	1,427,000		1,850,000
Interest income recognized	88,000	53,000		21,000
Non-PCI Loans | Noncommercial | Non-specific
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		(15,772,000)	[1]
Non-PCI Loans | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment, Change During Period	2,000,000
Non-PCI Loans | With A Recorded Allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	87,007,000	83,678,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	996,000	1,025,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	57,324,000	57,819,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	112,000	783,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	10,319,000	7,197,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	319,000	133,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	2,000,000
Non-PCI Loans | With A Recorded Allowance | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	10,198,000	11,534,000
Non-PCI Loans | With A Recorded Allowance | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,077,000	651,000
Non-PCI Loans | With A Recorded Allowance | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	3,675,000	3,382,000
Non-PCI Loans | With A Recorded Allowance | Noncommercial | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	987,000	1,154,000
Non-PCI Loans | With No Recorded Allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	32,586,000	48,468,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	624,000	1,247,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	25,479,000	39,292,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	472,000	1,095,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	721,000	2,103,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	304,000	55,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	0
Non-PCI Loans | With No Recorded Allowance | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	4,715,000	4,005,000
Non-PCI Loans | With No Recorded Allowance | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	263,000	457,000
Non-PCI Loans | With No Recorded Allowance | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	0	214,000
Non-PCI Loans | With No Recorded Allowance | Noncommercial | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	8,000	0
Loans Acquired With Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		0	[1]
Acquired loans which have adverse change in expected cash flows	$ 285,636,000	$ 459,947,000

[1] Reclassification results from enhancements to the ALLL calculation during the second quarter of 2013 that resulted in the allocation of $15.8 million previously designated as 'nonspecific' to other loan classes and the absorption of $7.4 million of the reserve for unfunded commitments related to unfunded, revocable loan commitments into the ALLL. Further discussion is contained in Note A.