Loans and Leases (Loans Acquired By Loan Class) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011
Total covered loans acquired	$ 2,183,869	[1]	$ 2,362,152	[2]	$ 2,658,134	[1]
Commercial Mortgage [Member]
Total covered loans acquired	1,745,709		1,872,685		2,171,294
Commercial Mortgage [Member] | Construction and Land Development [Member]
Total covered loans acquired	310,601		338,873		402,316
Commercial Mortgage [Member] | Commercial Mortgage [Member]
Total covered loans acquired	1,195,541		1,260,589		1,432,632
Commercial Mortgage [Member] | Other Commercial Real Estate [Member]
Total covered loans acquired	144,978		158,394		163,305
Commercial Mortgage [Member] | Commercial And Industrial [Member]
Total covered loans acquired	93,261		113,442		171,041
Commercial Mortgage [Member] | Lease Financing [Member]
Total covered loans acquired	45		57		271
Commercial Mortgage [Member] | Other Loans [Member]
Total covered loans acquired	1,283		1,330		1,729
Non-Commercial Loans [Member]
Total covered loans acquired	438,160		489,467		486,840
Non-Commercial Loans [Member] | Construction and Land Development [Member]
Total covered loans acquired	85,555		105,536		111,425
Non-Commercial Loans [Member] | Residential Mortgage [Member]
Total covered loans acquired	298,538		327,568		347,393
Non-Commercial Loans [Member] | Revolving Mortgage [Member]
Total covered loans acquired	50,016		51,552		23,409
Non-Commercial Loans [Member] | Consumer [Member]
Total covered loans acquired	4,051		4,811		4,613
Impaired At Acquisition Date [Member]
Total covered loans acquired	391,941		458,305		405,780
Impaired At Acquisition Date [Member] | Commercial Mortgage [Member]
Total covered loans acquired	272,736		317,240		321,624
Impaired At Acquisition Date [Member] | Commercial Mortgage [Member] | Construction and Land Development [Member]
Total covered loans acquired	100,736		117,603		112,271
Impaired At Acquisition Date [Member] | Commercial Mortgage [Member] | Commercial Mortgage [Member]
Total covered loans acquired	122,876		138,465		141,869
Impaired At Acquisition Date [Member] | Commercial Mortgage [Member] | Other Commercial Real Estate [Member]
Total covered loans acquired	31,727		33,370		36,338
Impaired At Acquisition Date [Member] | Commercial Mortgage [Member] | Commercial And Industrial [Member]
Total covered loans acquired	17,397		27,802		31,124
Impaired At Acquisition Date [Member] | Commercial Mortgage [Member] | Lease Financing [Member]
Total covered loans acquired	0		0		22
Impaired At Acquisition Date [Member] | Commercial Mortgage [Member] | Other Loans [Member]
Total covered loans acquired	0		0		0
Impaired At Acquisition Date [Member] | Non-Commercial Loans [Member]
Total covered loans acquired	119,205		141,065		84,156
Impaired At Acquisition Date [Member] | Non-Commercial Loans [Member] | Construction and Land Development [Member]
Total covered loans acquired	56,722		78,108		56,829
Impaired At Acquisition Date [Member] | Non-Commercial Loans [Member] | Residential Mortgage [Member]
Total covered loans acquired	46,905		46,130		19,846
Impaired At Acquisition Date [Member] | Non-Commercial Loans [Member] | Revolving Mortgage [Member]
Total covered loans acquired	14,125		15,350		7,341
Impaired At Acquisition Date [Member] | Non-Commercial Loans [Member] | Consumer [Member]
Total covered loans acquired	1,453		1,477		140
All Other Acquired Loans [Member]
Total covered loans acquired	1,791,928		1,903,847		2,252,354
All Other Acquired Loans [Member] | Commercial Mortgage [Member]
Total covered loans acquired	1,472,973		1,555,445		1,849,670
All Other Acquired Loans [Member] | Commercial Mortgage [Member] | Construction and Land Development [Member]
Total covered loans acquired	209,865		221,270		290,045
All Other Acquired Loans [Member] | Commercial Mortgage [Member] | Commercial Mortgage [Member]
Total covered loans acquired	1,072,665		1,122,124		1,290,763
All Other Acquired Loans [Member] | Commercial Mortgage [Member] | Other Commercial Real Estate [Member]
Total covered loans acquired	113,251		125,024		126,967
All Other Acquired Loans [Member] | Commercial Mortgage [Member] | Commercial And Industrial [Member]
Total covered loans acquired	75,864		85,640		139,917
All Other Acquired Loans [Member] | Commercial Mortgage [Member] | Lease Financing [Member]
Total covered loans acquired	45		57		249
All Other Acquired Loans [Member] | Commercial Mortgage [Member] | Other Loans [Member]
Total covered loans acquired	1,283		1,330		1,729
All Other Acquired Loans [Member] | Non-Commercial Loans [Member]
Total covered loans acquired	318,955		348,402		402,684
All Other Acquired Loans [Member] | Non-Commercial Loans [Member] | Construction and Land Development [Member]
Total covered loans acquired	28,833		27,428		54,596
All Other Acquired Loans [Member] | Non-Commercial Loans [Member] | Residential Mortgage [Member]
Total covered loans acquired	251,633		281,438		327,547
All Other Acquired Loans [Member] | Non-Commercial Loans [Member] | Revolving Mortgage [Member]
Total covered loans acquired	35,891		36,202		16,068
All Other Acquired Loans [Member] | Non-Commercial Loans [Member] | Consumer [Member]
Total covered loans acquired	$ 2,598		$ 3,334		$ 4,473

[1] Unaudited

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