Loans and Leases (Loans Acquired By Loan Class) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 1,621,327	[1]	$ 1,809,235	[2]	$ 2,183,869	[1]
Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,292,943		1,450,035		1,745,709
Commercial Mortgage | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	204,524		237,906		310,601
Commercial Mortgage | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	948,452		1,054,473		1,195,541
Commercial Mortgage | Other Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	93,232		107,119		144,978
Commercial Mortgage | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	45,693		49,463		93,261
Commercial Mortgage | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	0		0		45
Commercial Mortgage | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,042		1,074		1,283
Non-Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	328,384		359,200		438,160
Non-Commercial Loans | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	11,024		20,793		85,555
Non-Commercial Loans | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	278,997		297,926		298,538
Non-Commercial Loans | Revolving Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	37,139		38,710		50,016
Non-Commercial Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,224		1,771		4,051
Impaired At Acquisition Date
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	255,267		290,626		391,941
Impaired At Acquisition Date | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	190,946		217,807		272,736
Impaired At Acquisition Date | Commercial Mortgage | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	53,209		71,225		100,736
Impaired At Acquisition Date | Commercial Mortgage | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	101,397		107,281		122,876
Impaired At Acquisition Date | Commercial Mortgage | Other Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	30,191		35,369		31,727
Impaired At Acquisition Date | Commercial Mortgage | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	6,149		3,932		17,397
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	64,321		72,819		119,205
Impaired At Acquisition Date | Non-Commercial Loans | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	10,609		15,136		56,722
Impaired At Acquisition Date | Non-Commercial Loans | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	43,924		48,077		46,905
Impaired At Acquisition Date | Non-Commercial Loans | Revolving Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	9,788		9,606		14,125
Impaired At Acquisition Date | Non-Commercial Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	0		0		1,453
All Other Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,366,060		1,518,609		1,791,928
All Other Acquired Loans | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,101,997		1,232,228		1,472,973
All Other Acquired Loans | Commercial Mortgage | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	151,315		166,681		209,865
All Other Acquired Loans | Commercial Mortgage | Commercial Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	847,055		947,192		1,072,665
All Other Acquired Loans | Commercial Mortgage | Other Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	63,041		71,750		113,251
All Other Acquired Loans | Commercial Mortgage | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	39,544		45,531		75,864
All Other Acquired Loans | Commercial Mortgage | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	0		0		45
All Other Acquired Loans | Commercial Mortgage | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	1,042		1,074		1,283
All Other Acquired Loans | Non-Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	264,063		286,381		318,955
All Other Acquired Loans | Non-Commercial Loans | Construction and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	415		5,657		28,833
All Other Acquired Loans | Non-Commercial Loans | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	235,073		249,849		251,633
All Other Acquired Loans | Non-Commercial Loans | Revolving Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	27,351		29,104		35,891
All Other Acquired Loans | Non-Commercial Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 1,224		$ 1,771		$ 2,598

[1] Unaudited

[2] Derived from 2012 Annual Report on Form 10-K.