Loans and Allowance for Loan Losses - Composition of Loans, Net of Unearned income (Parenthetical) (Detail) (USD $)	Mar. 31, 2013		Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 8,844,890,000	[1]	$ 8,946,933,000	[1]
Credit Card Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan portfolio	77,000,000		64,100,000
Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	824,183,000		829,957,000
Real estate secured loans | Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	724,894,000	[2]	685,300,000	[2]
Real estate secured loans | Consumer Portfolio Segment | Loans for personal residence
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	541,115,000		503,378,000
Real estate secured loans | Consumer Portfolio Segment | Loans to eligible employees
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	112,314,000		110,584,000
Real estate secured loans | Consumer Portfolio Segment | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	71,465,000		71,338,000
Premium wine | Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross construction loans	$ 132,700,000		$ 147,900,000

[1] Included within our total loan portfolio are credit card loans of $77 million and $64 million at March 31, 2013 and December 31, 2012, respectively.

[2] Consumer loans secured by real estate at March 31, 2013 and December 31, 2012 were comprised of the following:(Dollars in thousands) March 31, 2013 December 31, 2012Loans for personal residence $541,115 $503,378Loans to eligible employees 112,314 110,584Home equity lines of credit 71,465 71,338Consumer loans secured by real estate $724,894 $685,300