Loans and Leases (Loans Acquired By Loan Class) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 1,897,097	[1]	$ 2,362,152	[2]	$ 2,557,450	[1]
Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,542,482		1,872,685		2,013,636
Commercial Mortgage | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	258,388		338,873		405,658
Commercial Mortgage | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,109,048		1,260,589		1,310,083
Commercial Mortgage | Other Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	113,954		158,394		159,007
Commercial Mortgage | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	59,787		113,442		137,253
Commercial Mortgage | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	0		57		162
Commercial Mortgage | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,305		1,330		1,473
Non-Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	354,615		489,467		543,814
Non-Commercial Loans | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	26,408		105,536		115,126
Non-Commercial Loans | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	289,160		327,568		380,405
Non-Commercial Loans | Revolving Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	37,280		51,552		39,709
Non-Commercial Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,767		4,811		8,574
Impaired At Acquisition Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	290,724		458,305		499,705
Impaired At Acquisition Date | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	214,628		317,240		368,813
Impaired At Acquisition Date | Commercial Mortgage | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	72,873		117,603		172,309
Impaired At Acquisition Date | Commercial Mortgage | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	103,219		138,465		125,379
Impaired At Acquisition Date | Commercial Mortgage | Other Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	29,769		33,370		40,514
Impaired At Acquisition Date | Commercial Mortgage | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	8,767		27,802		30,611
Impaired At Acquisition Date | Commercial Mortgage | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	0		0		0
Impaired At Acquisition Date | Commercial Mortgage | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	0		0		0
Impaired At Acquisition Date | Non-Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	76,096		141,065		130,892
Impaired At Acquisition Date | Non-Commercial Loans | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	19,008		78,108		74,414
Impaired At Acquisition Date | Non-Commercial Loans | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	48,245		46,130		45,384
Impaired At Acquisition Date | Non-Commercial Loans | Revolving Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	8,787		15,350		9,939
Impaired At Acquisition Date | Non-Commercial Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	56		1,477		1,155
All Other Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,606,373		1,903,847		2,057,745
All Other Acquired Loans | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,327,854		1,555,445		1,644,823
All Other Acquired Loans | Commercial Mortgage | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	185,515		221,270		233,349
All Other Acquired Loans | Commercial Mortgage | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,005,829		1,122,124		1,184,704
All Other Acquired Loans | Commercial Mortgage | Other Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	84,185		125,024		118,493
All Other Acquired Loans | Commercial Mortgage | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	51,020		85,640		106,642
All Other Acquired Loans | Commercial Mortgage | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	0		57		162
All Other Acquired Loans | Commercial Mortgage | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,305		1,330		1,473
All Other Acquired Loans | Non-Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	278,519		348,402		412,922
All Other Acquired Loans | Non-Commercial Loans | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	7,400		27,428		40,712
All Other Acquired Loans | Non-Commercial Loans | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	240,915		281,438		335,021
All Other Acquired Loans | Non-Commercial Loans | Revolving Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	28,493		36,202		29,770
All Other Acquired Loans | Non-Commercial Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 1,711		$ 3,334		$ 7,419

[1] Unaudited

[2] Derived from 2011 Annual Report on Form 10-K.