Estimated Fair Values (Estimated Fair Values For Certain Financial Assets And Financial Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 604,182		$ 533,599
Overnight investments	1,724,919		859,324
Investment securities available for sale	7,171,917		5,387,703
Investment securities held to maturity	518		907
Loans and Leases Receivable, Net Amount	18,564,999		12,900,330
FDIC Indemnification Asset	28,701		93,397		270,192	617,377
Income earned not collected	57,254		48,390
Servicing Asset	16,688		16		1,784
Deposits	25,678,577		17,874,066
Short-term borrowings	987,184		511,418
Long-term obligations	351,320		510,769
FDIC loss share payable	116,535		109,378
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	604,182		533,599
Overnight investments	1,724,919		859,324
Investment securities available for sale	7,171,917		5,387,703
Investment securities held to maturity	518		907
Loans held for sale	63,696		47,271
Loans and Leases Receivable, Net Amount	18,564,999		12,900,330
FDIC Indemnification Asset	28,701	[1]	93,397	[1]
Income earned not collected	57,254		48,390
Stock issued by Federal Home Loan Bank	39,113		40,819
Preferred stock	13,689		33,564
Servicing Asset	16,688		16
Deposits	25,678,577		17,874,066
Short-term borrowings	987,184		511,418
Long-term obligations	351,320		510,769
FDIC loss share payable	116,535		109,378
Accrued interest payable	8,194		6,737
Derivative Liability, Fair Value, Gross Liability	4,337		7,220
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	604,182		533,599
Overnight investments	1,724,919		859,324
Investment securities available for sale	7,171,917		5,387,703
Investment securities held to maturity	544		974
Loans held for sale	63,696		47,956
Loans and Leases Receivable, Net Amount	18,046,497		12,545,537
FDIC Indemnification Asset	18,218	[1]	38,438	[1]
Income earned not collected	57,254		48,390
Stock issued by Federal Home Loan Bank	39,113		40,819
Preferred stock	14,708		34,786
Servicing Asset	16,736		16
Deposits	25,164,683		17,898,570
Short-term borrowings	987,184		511,418
Long-term obligations	367,732		526,037
FDIC loss share payable	122,168		111,941
Accrued interest payable	8,194		6,737
Derivative Liability, Fair Value, Gross Liability	$ 4,337		$ 7,220

[1] The fair value of the FDIC receivable excludes receivable related to accretable yield to be amortized in prospective periods.