Loans (Schedule Of Loan Portfolio Aging Excluding Covered Assets) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Loans [Line Items]
Loan Portfolio Aging, Current	$ 9,213,712	$ 8,720,387
Loan Portfolio Aging, Total Accruing Loans	9,226,896	8,748,709
Loan Portfolio Aging, Nonaccrual	209,339	259,852
Total Loans	9,436,235	9,008,561	8,672,642
Commercial Loan [Member]
Loans [Line Items]
Loan Portfolio Aging, Current	5,842,805	5,250,875
Loan Portfolio Aging, Total Accruing Loans	5,848,770	5,257,816
Loan Portfolio Aging, Nonaccrual	59,841	65,958
Total Loans	5,908,611	5,323,774
Commercial Real Estate [Member]
Loans [Line Items]
Loan Portfolio Aging, Current	2,500,441	2,539,889
Loan Portfolio Aging, Total Accruing Loans	2,504,298	2,553,189
Loan Portfolio Aging, Nonaccrual	119,444	133,257
Total Loans	2,623,742	2,686,446
Construction Loans [Member]
Loans [Line Items]
Loan Portfolio Aging, Current	170,459	262,742
Loan Portfolio Aging, Total Accruing Loans	170,459	265,123
Loan Portfolio Aging, Nonaccrual	555	21,879
Total Loans	171,014	287,002
Residential Real Estate [Member]
Loans [Line Items]
Loan Portfolio Aging, Current	318,864	278,195
Loan Portfolio Aging, Total Accruing Loans	319,226	282,640
Loan Portfolio Aging, Nonaccrual	11,028	14,589
Total Loans	330,254	297,229
Home Equity Line of Credit [Member]
Loans [Line Items]
Loan Portfolio Aging, Current	159,076	168,322
Loan Portfolio Aging, Total Accruing Loans	162,068	169,555
Loan Portfolio Aging, Nonaccrual	12,063	11,603
Total Loans	174,131	181,158
Consumer Loan [Member]
Loans [Line Items]
Loan Portfolio Aging, Current	222,067	220,364
Loan Portfolio Aging, Total Accruing Loans	222,075	220,386
Loan Portfolio Aging, Nonaccrual	6,408	12,566
Total Loans	228,483	232,952
Delinquent [Member]
Loans [Line Items]
Loan Portfolio Aging, 30 - 59 Days Past Due	4,539	13,787
Loan Portfolio Aging, 60 - 89 Days Past Due	8,645	14,535
Loan Portfolio Aging, 90 Days Past Due and Accruing
Delinquent [Member] | Commercial Loan [Member]
Loans [Line Items]
Loan Portfolio Aging, 30 - 59 Days Past Due	901	6,018
Loan Portfolio Aging, 60 - 89 Days Past Due	5,064	923
Loan Portfolio Aging, 90 Days Past Due and Accruing
Delinquent [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Loan Portfolio Aging, 30 - 59 Days Past Due	1,314	3,523
Loan Portfolio Aging, 60 - 89 Days Past Due	2,543	9,777
Loan Portfolio Aging, 90 Days Past Due and Accruing
Delinquent [Member] | Construction Loans [Member]
Loans [Line Items]
Loan Portfolio Aging, 60 - 89 Days Past Due		2,381
Loan Portfolio Aging, 90 Days Past Due and Accruing
Delinquent [Member] | Residential Real Estate [Member]
Loans [Line Items]
Loan Portfolio Aging, 30 - 59 Days Past Due	341	3,800
Loan Portfolio Aging, 60 - 89 Days Past Due	21	645
Loan Portfolio Aging, 90 Days Past Due and Accruing
Delinquent [Member] | Home Equity Line of Credit [Member]
Loans [Line Items]
Loan Portfolio Aging, 30 - 59 Days Past Due	1,983	433
Loan Portfolio Aging, 60 - 89 Days Past Due	1,009	800
Loan Portfolio Aging, 90 Days Past Due and Accruing
Delinquent [Member] | Consumer Loan [Member]
Loans [Line Items]
Loan Portfolio Aging, 30 - 59 Days Past Due		13
Loan Portfolio Aging, 60 - 89 Days Past Due	8	9
Loan Portfolio Aging, 90 Days Past Due and Accruing