Composition of Loans, Net of Unearned income (Parenthetical) (Detail) (USD $)	Sep. 30, 2012		Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 8,192,369,000	[1]	$ 6,970,082,000	[1]
Credit Card Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	66,200,000		49,700,000
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	752,976,000		695,138,000
Real estate secured loans | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	609,370,000	[2]	534,001,000	[2]
Real estate secured loans | Consumer Portfolio Segment [Member] | Loans for personal residence
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	432,004,000		350,359,000
Real estate secured loans | Consumer Portfolio Segment [Member] | Loans to eligible employees
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	107,969,000		99,704,000
Real estate secured loans | Consumer Portfolio Segment [Member] | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	69,397,000		83,938,000
Premium wine | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, Gross, Commercial, Construction	$ 148,400,000		$ 110,800,000

[1] Included within our total loan portfolio are credit card loans of $66.2 million and $49.7 million at September 30, 2012 and December 31, 2011, respectively.

[2] Consumer loans secured by real estate at September 30, 2012 and December 31, 2011 were comprised of the following: