Allowance for Loan and Lease Losses (Allocation of Allowance for Loan and Lease Losses) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	$ 2,092,936,000	$ 1,727,492,000
Allowance for loan and lease losses	205,553,000		204,466,000
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	126,823,000		133,466,000
ALLL for loans and leases individually evaluated for impairment	14,686,000		15,717,000
Financing Receivable, Individually Evaluated for Impairment	118,078,000		119,593,000
Average balance	121,995,000	131,647,000
Interest income recognized	1,093,000	1,513,000
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	4,228,000		6,945,000
ALLL for loans and leases individually evaluated for impairment	182,000		92,000
Financing Receivable, Individually Evaluated for Impairment	2,972,000		1,620,000
Average balance	3,052,000	1,031,000
Interest income recognized	35,000	15,000
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	81,826,000		87,702,000
ALLL for loans and leases individually evaluated for impairment	7,494,000		8,610,000
Financing Receivable, Individually Evaluated for Impairment	77,291,000		82,803,000
Average balance	80,553,000	94,547,000
Interest income recognized	769,000	1,120,000
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	847,000		913,000
ALLL for loans and leases individually evaluated for impairment	104,000		112,000
Financing Receivable, Individually Evaluated for Impairment	543,000		584,000
Average balance	551,000	1,796,000
Interest income recognized	1,000	21,000
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	14,939,000		12,197,000
ALLL for loans and leases individually evaluated for impairment	2,809,000		1,743,000
Financing Receivable, Individually Evaluated for Impairment	13,969,000		11,040,000
Average balance	14,229,000	10,234,000
Interest income recognized	103,000	118,000
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,492,000		623,000
ALLL for loans and leases individually evaluated for impairment	236,000		150,000
Financing Receivable, Individually Evaluated for Impairment	1,492,000		623,000
Average balance	1,590,000	284,000
Interest income recognized	18,000	4,000
Non-PCI Loans | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,977,000		2,000,000
ALLL for loans and leases individually evaluated for impairment	1,955,000		1,972,000
Financing Receivable, Individually Evaluated for Impairment	1,977,000		2,000,000
Average balance	1,990,000	0
Interest income recognized	0	0
Non-PCI Loans | Noncommerical | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	15,852,000		15,746,000
ALLL for loans and leases individually evaluated for impairment	1,177,000		1,360,000
Financing Receivable, Individually Evaluated for Impairment	15,195,000		14,913,000
Average balance	15,364,000	16,482,000
Interest income recognized	125,000	174,000
Non-PCI Loans | Noncommerical | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	733,000		1,340,000
ALLL for loans and leases individually evaluated for impairment	90,000		71,000
Financing Receivable, Individually Evaluated for Impairment	733,000		1,340,000
Average balance	658,000	2,322,000
Interest income recognized	7,000	29,000
Non-PCI Loans | Noncommerical | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	3,925,000		4,933,000
ALLL for loans and leases individually evaluated for impairment	108,000		1,052,000
Financing Receivable, Individually Evaluated for Impairment	2,922,000		3,675,000
Average balance	2,986,000	3,892,000
Interest income recognized	16,000	27,000
Non-PCI Loans | Noncommerical | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,004,000		1,067,000
ALLL for loans and leases individually evaluated for impairment	531,000		555,000
Financing Receivable, Individually Evaluated for Impairment	984,000		995,000
Average balance	1,022,000	1,059,000
Interest income recognized	19,000	5,000
Non-PCI Loans | With A Recorded Allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	83,497,000		87,007,000
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	2,114,000		996,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	53,220,000		57,324,000
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	104,000		112,000
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	13,123,000		10,319,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,221,000		319,000
Non-PCI Loans | With A Recorded Allowance | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,977,000		2,000,000
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	8,662,000		10,198,000
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	733,000		1,077,000
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,439,000		3,675,000
Non-PCI Loans | With A Recorded Allowance | Noncommerical | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	904,000		987,000
Non-PCI Loans | With No Recorded Allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	34,581,000		32,586,000
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	858,000		624,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	24,071,000		25,479,000
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	439,000		472,000
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	846,000		721,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	271,000		304,000
Non-PCI Loans | With No Recorded Allowance | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	0		0
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	6,533,000		4,715,000
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	0		263,000
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	1,483,000		0
Non-PCI Loans | With No Recorded Allowance | Noncommerical | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	80,000		8,000
PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans which have adverse change in expected cash flows	$ 438,200,000		$ 285,600,000