Allowance for Loan and Lease Losses (Summary of Activity In Allowance for Loan and Lease Losses) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Loans and Leases, Baseline for Meaurement						$ 500,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Net loans and leases					$ 19,650,343,000	18,564,999,000
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					1,044,064,000	1,186,498,000	$ 996,280,000	$ 1,029,426,000
Allowance for loan and lease losses					205,463,000	204,466,000
Commercial
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					646,961,000	726,123,000
Commercial | Construction and land development
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					41,582,000	78,079,000
Commercial | Mortgage
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					568,256,000	577,518,000
Commercial | Other commercial real estate
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					18,013,000	40,193,000
Commercial | Commercial and industrial
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					17,023,000	27,254,000
Commercial | Other
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					2,087,000	3,079,000
Noncommerical
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					397,103,000	460,375,000
Noncommerical | Construction and land development
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					347,000	912,000
Noncommerical | Mortgage
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					334,518,000	382,340,000
Noncommerical | Revolving mortgage
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					59,695,000	74,109,000
Noncommerical | Consumer
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					2,543,000	3,014,000
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Related Allowance					8,491,000	15,717,000
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 192,849,000	$ 176,915,000	$ 182,837,000	$ 179,874,000
Provision for Loan, Lease, and Other Losses	(2,662,000)	1,734,000	14,988,000	4,334,000
Charge-offs	(5,018,000)	(5,387,000)	(17,098,000)	(14,578,000)
Recoveries	2,737,000	1,843,000	7,179,000	5,475,000
Ending balance	187,906,000	175,105,000	187,906,000	175,105,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					142,962,000	119,593,000
Loans and leases collectively evaluated for impairment					18,668,780,000	17,463,374,000
Net loans and leases					18,811,742,000	17,582,967,000
ALLL for loans and leases individually evaluated for impairment					8,491,000	15,717,000
ALLL for loans and leases collectively evaluated for impairment					179,415,000	167,120,000
Total allowance for loan and lease losses	192,849,000	176,915,000	182,837,000	179,874,000	187,906,000	182,837,000	175,105,000	179,874,000
Non-PCI Loans | Commercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	13,079,000	11,116,000	11,961,000	10,335,000
Provision for Loan, Lease, and Other Losses	1,189,000	1,469,000	2,380,000	2,219,000
Charge-offs	(336,000)	0	(575,000)	0
Recoveries	129,000	15,000	295,000	46,000
Ending balance	14,061,000	12,600,000	14,061,000	12,600,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					3,194,000	1,620,000
Loans and leases collectively evaluated for impairment					560,732,000	491,513,000
Net loans and leases					563,926,000	493,133,000
ALLL for loans and leases individually evaluated for impairment					417,000	92,000
ALLL for loans and leases collectively evaluated for impairment					13,644,000	11,869,000
Total allowance for loan and lease losses	13,079,000	11,116,000	11,961,000	10,335,000	14,061,000	11,961,000	12,600,000	10,335,000
Non-PCI Loans | Commercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	80,436,000	92,129,000	85,189,000	100,257,000
Provision for Loan, Lease, and Other Losses	(5,664,000)	(8,082,000)	(11,221,000)	(17,021,000)
Charge-offs	(411,000)	(277,000)	(691,000)	(718,000)
Recoveries	794,000	476,000	1,878,000	1,728,000
Ending balance	75,155,000	84,246,000	75,155,000	84,246,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					92,745,000	82,803,000
Loans and leases collectively evaluated for impairment					7,984,201,000	7,470,145,000
Net loans and leases					8,076,946,000	7,552,948,000
ALLL for loans and leases individually evaluated for impairment					4,007,000	8,610,000
ALLL for loans and leases collectively evaluated for impairment					71,148,000	76,579,000
Total allowance for loan and lease losses	80,436,000	92,129,000	85,189,000	100,257,000	75,155,000	85,189,000	84,246,000	100,257,000
Non-PCI Loans | Commercial | Other commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	804,000	806,000	732,000	1,009,000
Provision for Loan, Lease, and Other Losses	291,000	61,000	522,000	(167,000)
Charge-offs	0	0	(178,000)	0
Recoveries	15,000	8,000	34,000	33,000
Ending balance	1,110,000	875,000	1,110,000	875,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					436,000	584,000
Loans and leases collectively evaluated for impairment					316,488,000	244,291,000
Net loans and leases					316,924,000	244,875,000
ALLL for loans and leases individually evaluated for impairment					295,000	112,000
ALLL for loans and leases collectively evaluated for impairment					815,000	620,000
Total allowance for loan and lease losses	804,000	806,000	732,000	1,009,000	1,110,000	732,000	875,000	1,009,000
Non-PCI Loans | Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	39,392,000	26,909,000	30,727,000	22,362,000
Provision for Loan, Lease, and Other Losses	(799,000)	4,361,000	11,294,000	9,369,000
Charge-offs	(784,000)	(1,414,000)	(4,815,000)	(2,440,000)
Recoveries	296,000	227,000	899,000	792,000
Ending balance	38,105,000	30,083,000	38,105,000	30,083,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					16,395,000	11,040,000
Loans and leases collectively evaluated for impairment					2,195,578,000	1,977,894,000
Net loans and leases					2,211,973,000	1,988,934,000
ALLL for loans and leases individually evaluated for impairment					1,154,000	1,743,000
ALLL for loans and leases collectively evaluated for impairment					36,951,000	28,984,000
Total allowance for loan and lease losses	39,392,000	26,909,000	30,727,000	22,362,000	38,105,000	30,727,000	30,083,000	22,362,000
Non-PCI Loans | Commercial | Lease financing
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	4,706,000	4,365,000	4,286,000	4,749,000
Provision for Loan, Lease, and Other Losses	424,000	(71,000)	843,000	(420,000)
Charge-offs	(7,000)	(28,000)	(28,000)	(100,000)
Recoveries	16,000	34,000	38,000	71,000
Ending balance	5,139,000	4,300,000	5,139,000	4,300,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					1,908,000	623,000
Loans and leases collectively evaluated for impairment					690,007,000	571,293,000
Net loans and leases					691,915,000	571,916,000
ALLL for loans and leases individually evaluated for impairment					291,000	150,000
ALLL for loans and leases collectively evaluated for impairment					4,848,000	4,136,000
Total allowance for loan and lease losses	4,706,000	4,365,000	4,286,000	4,749,000	5,139,000	4,286,000	4,300,000	4,749,000
Non-PCI Loans | Commercial | Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,188,000	612,000	3,184,000	190,000
Provision for Loan, Lease, and Other Losses	(58,000)	127,000	(2,100,000)	562,000
Charge-offs	0	0	0	(13,000)
Recoveries	45,000	0	91,000	0
Ending balance	1,175,000	739,000	1,175,000	739,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					1,464,000	2,000,000
Loans and leases collectively evaluated for impairment					356,296,000	351,833,000
Net loans and leases					357,760,000	353,833,000
ALLL for loans and leases individually evaluated for impairment					67,000	1,972,000
ALLL for loans and leases collectively evaluated for impairment					1,108,000	1,212,000
Total allowance for loan and lease losses	1,188,000	612,000	3,184,000	190,000	1,175,000	3,184,000	739,000	190,000
Non-PCI Loans | Noncommerical | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,133,000	905,000	892,000	681,000
Provision for Loan, Lease, and Other Losses	114,000	21,000	306,000	274,000
Charge-offs	0	(45,000)	(22,000)	(138,000)
Recoveries	3,000	14,000	74,000	78,000
Ending balance	1,250,000	895,000	1,250,000	895,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					1,045,000	1,340,000
Loans and leases collectively evaluated for impairment					219,448,000	203,676,000
Net loans and leases					220,493,000	205,016,000
ALLL for loans and leases individually evaluated for impairment					78,000	71,000
ALLL for loans and leases collectively evaluated for impairment					1,172,000	821,000
Total allowance for loan and lease losses	1,133,000	905,000	892,000	681,000	1,250,000	892,000	895,000	681,000
Non-PCI Loans | Noncommerical | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	12,705,000	9,301,000	10,661,000	10,511,000
Provision for Loan, Lease, and Other Losses	520,000	15,000	2,495,000	(933,000)
Charge-offs	(394,000)	(231,000)	(768,000)	(649,000)
Recoveries	314,000	28,000	757,000	184,000
Ending balance	13,145,000	9,113,000	13,145,000	9,113,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					19,691,000	14,913,000
Loans and leases collectively evaluated for impairment					2,640,130,000	2,478,145,000
Net loans and leases					2,659,821,000	2,493,058,000
ALLL for loans and leases individually evaluated for impairment					1,158,000	1,360,000
ALLL for loans and leases collectively evaluated for impairment					11,987,000	9,301,000
Total allowance for loan and lease losses	12,705,000	9,301,000	10,661,000	10,511,000	13,145,000	10,661,000	9,113,000	10,511,000
Non-PCI Loans | Noncommerical | Revolving mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	17,290,000	16,797,000	18,650,000	16,239,000
Provision for Loan, Lease, and Other Losses	871,000	2,075,000	440,000	4,681,000
Charge-offs	(677,000)	(925,000)	(2,086,000)	(3,249,000)
Recoveries	363,000	174,000	843,000	450,000
Ending balance	17,847,000	18,121,000	17,847,000	18,121,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					4,986,000	3,675,000
Loans and leases collectively evaluated for impairment					2,514,986,000	2,558,125,000
Net loans and leases					2,519,972,000	2,561,800,000
ALLL for loans and leases individually evaluated for impairment					526,000	1,052,000
ALLL for loans and leases collectively evaluated for impairment					17,321,000	17,598,000
Total allowance for loan and lease losses	17,290,000	16,797,000	18,650,000	16,239,000	17,847,000	18,650,000	18,121,000	16,239,000
Non-PCI Loans | Noncommerical | Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	22,116,000	13,975,000	16,555,000	13,541,000
Provision for Loan, Lease, and Other Losses	450,000	1,758,000	10,029,000	5,770,000
Charge-offs	(2,409,000)	(2,467,000)	(7,935,000)	(7,271,000)
Recoveries	762,000	867,000	2,270,000	2,093,000
Ending balance	20,919,000	14,133,000	20,919,000	14,133,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment					1,098,000	995,000
Loans and leases collectively evaluated for impairment					1,190,914,000	1,116,459,000
Net loans and leases					1,192,012,000	1,117,454,000
ALLL for loans and leases individually evaluated for impairment					498,000	555,000
ALLL for loans and leases collectively evaluated for impairment					20,421,000	16,000,000
Total allowance for loan and lease losses	22,116,000	13,975,000	16,555,000	13,541,000	20,919,000	16,555,000	14,133,000	13,541,000
PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	15,468,000	29,331,000	21,629,000	53,520,000
Provision for Loan, Lease, and Other Losses	2,769,000	(197,000)	(1,370,000)	(11,999,000)
Charge-offs	(680,000)	(3,334,000)	(2,702,000)	(15,721,000)
Recoveries	0	0	0	0
Ending balance	17,557,000	25,800,000	17,557,000	25,800,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	15,468,000	29,331,000	21,629,000	53,520,000	17,557,000	21,629,000	25,800,000	53,520,000
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					1,044,064,000	1,186,498,000
PCI Loans | Commercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	569,000	3,803,000	150,000	1,320,000
Provision for Loan, Lease, and Other Losses	632,000	(1,815,000)	1,148,000	1,463,000
Charge-offs	0	(1,633,000)	(97,000)	(2,428,000)
Recoveries	0	0	0	0
Ending balance	1,201,000	355,000	1,201,000	355,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	569,000	3,803,000	150,000	1,320,000	1,201,000	150,000	355,000	1,320,000
PCI Loans | Commercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	6,428,000	17,315,000	10,135,000	29,906,000
Provision for Loan, Lease, and Other Losses	2,187,000	(2,374,000)	(803,000)	(6,946,000)
Charge-offs	(48,000)	(2,357,000)	(765,000)	(10,376,000)
Recoveries	0	0	0	0
Ending balance	8,567,000	12,584,000	8,567,000	12,584,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	6,428,000	17,315,000	10,135,000	29,906,000	8,567,000	10,135,000	12,584,000	29,906,000
PCI Loans | Commercial | Other commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	69,000	407,000	75,000	1,354,000
Provision for Loan, Lease, and Other Losses	$ 235,000	(435,000)	229,000	(1,382,000)
Charge-offs		106,000	0	106,000
Recoveries	$ 0	0	0	0
Ending balance	304,000	78,000	304,000	78,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	69,000	407,000	75,000	1,354,000	304,000	75,000	78,000	1,354,000
PCI Loans | Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	323,000	375,000	1,240,000	5,275,000
Provision for Loan, Lease, and Other Losses	118,000	182,000	(514,000)	(1,883,000)
Charge-offs	(39,000)	839,000	(324,000)	(1,996,000)
Recoveries	0	0	0	0
Ending balance	402,000	1,396,000	402,000	1,396,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	323,000	375,000	1,240,000	5,275,000	402,000	1,240,000	1,396,000	5,275,000
PCI Loans | Noncommerical | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	0	183,000	682,000
Provision for Loan, Lease, and Other Losses	0	239,000	(183,000)	(443,000)
Charge-offs	0	(83,000)	0	(83,000)
Recoveries	0	0	0	0
Ending balance	0	156,000	0	156,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	0	0	183,000	682,000	0	183,000	156,000	682,000
PCI Loans | Noncommerical | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,842,000	7,093,000	5,820,000	11,802,000
Provision for Loan, Lease, and Other Losses	(281,000)	187,000	21,000	(4,289,000)
Charge-offs	(15,000)	(188,000)	(295,000)	(421,000)
Recoveries	0	0	0	0
Ending balance	5,546,000	7,092,000	5,546,000	7,092,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	5,842,000	7,093,000	5,820,000	11,802,000	5,546,000	5,820,000	7,092,000	11,802,000
PCI Loans | Noncommerical | Revolving mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,051,000	81,000	3,999,000	2,959,000
Provision for Loan, Lease, and Other Losses	(151,000)	3,899,000	(1,918,000)	1,502,000
Charge-offs	(577,000)	(1,000)	(758,000)	(482,000)
Recoveries	0	0	0	0
Ending balance	1,323,000	3,979,000	1,323,000	3,979,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	2,051,000	81,000	3,999,000	2,959,000	1,323,000	3,999,000	3,979,000	2,959,000
PCI Loans | Noncommerical | Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	186,000	257,000	27,000	222,000
Provision for Loan, Lease, and Other Losses	29,000	(80,000)	650,000	(21,000)
Charge-offs	(1,000)	(17,000)	(463,000)	(41,000)
Recoveries	0	0	0	0
Ending balance	214,000	160,000	214,000	160,000
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	$ 186,000	$ 257,000	$ 27,000	$ 222,000	214,000	27,000	$ 160,000	$ 222,000
Loan and Leases Acquired with Deteriorated Credit Quality [Abstract]
Loans and leases acquired with deteriorated credit quality					$ 4,630,000	$ 6,093,000