Loans and Leases (Loans Acquired By Loan Class) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011		Jun. 30, 2011
Covered loans	$ 1,999,351	[1]	$ 2,362,152	[2]	$ 2,399,738	[1]
Commercial Mortgage
Covered loans	1,598,579		1,872,685		1,947,422
Commercial Mortgage | Construction and Land Development
Covered loans	272,445		338,873		338,650
Commercial Mortgage | Commercial Mortgage
Covered loans	1,142,677		1,260,589		1,307,775
Commercial Mortgage | Other Commercial Real Estate
Covered loans	115,787		158,394		173,606
Commercial Mortgage | Commercial and Industrial
Covered loans	66,442		113,442		125,492
Commercial Mortgage | Lease Financing
Covered loans	0		57		224
Commercial Mortgage | Other
Covered loans	1,228		1,330		1,675
Non-Commercial Loans
Covered loans	400,772		489,467		452,316
Non-Commercial Loans | Construction and Land Development
Covered loans	39,294		105,536		82,177
Non-Commercial Loans | Residential Mortgage
Covered loans	322,053		327,568		354,033
Non-Commercial Loans | Revolving Mortgage
Covered loans	37,110		51,552		11,933
Non-Commercial Loans | Consumer
Covered loans	2,315		4,811		4,173
Impaired At Acquisition Date
Covered loans	337,648		458,305		310,399
Impaired At Acquisition Date | Commercial Mortgage
Covered loans	241,606		317,240		248,103
Impaired At Acquisition Date | Commercial Mortgage | Construction and Land Development
Covered loans	86,056		117,603		83,844
Impaired At Acquisition Date | Commercial Mortgage | Commercial Mortgage
Covered loans	121,580		138,465		120,916
Impaired At Acquisition Date | Commercial Mortgage | Other Commercial Real Estate
Covered loans	29,199		33,370		35,347
Impaired At Acquisition Date | Commercial Mortgage | Commercial and Industrial
Covered loans	4,771		27,802		7,990
Impaired At Acquisition Date | Commercial Mortgage | Lease Financing
Covered loans	0		0		6
Impaired At Acquisition Date | Commercial Mortgage | Other
Covered loans	0		0		0
Impaired At Acquisition Date | Non-Commercial Loans
Covered loans	96,042		141,065		62,296
Impaired At Acquisition Date | Non-Commercial Loans | Construction and Land Development
Covered loans	31,767		78,108		42,056
Impaired At Acquisition Date | Non-Commercial Loans | Residential Mortgage
Covered loans	55,585		46,130		19,635
Impaired At Acquisition Date | Non-Commercial Loans | Revolving Mortgage
Covered loans	8,286		15,350		483
Impaired At Acquisition Date | Non-Commercial Loans | Consumer
Covered loans	404		1,477		122
All Other Acquired Loans
Covered loans	1,661,703		1,903,847		2,089,339
All Other Acquired Loans | Commercial Mortgage
Covered loans	1,356,973		1,555,445		1,699,319
All Other Acquired Loans | Commercial Mortgage | Construction and Land Development
Covered loans	186,389		221,270		254,806
All Other Acquired Loans | Commercial Mortgage | Commercial Mortgage
Covered loans	1,021,097		1,122,124		1,186,859
All Other Acquired Loans | Commercial Mortgage | Other Commercial Real Estate
Covered loans	86,588		125,024		138,259
All Other Acquired Loans | Commercial Mortgage | Commercial and Industrial
Covered loans	61,671		85,640		117,502
All Other Acquired Loans | Commercial Mortgage | Lease Financing
Covered loans	0		57		218
All Other Acquired Loans | Commercial Mortgage | Other
Covered loans	1,228		1,330		1,675
All Other Acquired Loans | Non-Commercial Loans
Covered loans	304,730		348,402		390,020
All Other Acquired Loans | Non-Commercial Loans | Construction and Land Development
Covered loans	7,527		27,428		40,121
All Other Acquired Loans | Non-Commercial Loans | Residential Mortgage
Covered loans	266,468		281,438		334,398
All Other Acquired Loans | Non-Commercial Loans | Revolving Mortgage
Covered loans	28,824		36,202		11,450
All Other Acquired Loans | Non-Commercial Loans | Consumer
Covered loans	$ 1,911		$ 3,334		$ 4,051

[1] Unaudited

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