Loans and Allowance for Loan Losses - Composition of Loans, Net of Unearned income (Parenthetical) (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 11,348,711,000	$ 10,906,386,000
Credit Card Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan portfolio	109,000,000	85,000,000
Real estate secured loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	984,583,000	873,255,000
Real estate secured loans | Loans for personal residence
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	785,914,000	685,327,000
Real estate secured loans | Loans to eligible employees
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	129,116,000	121,548,000
Real estate secured loans | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	69,553,000	66,380,000
Premium wine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross construction loans	107,000,000	112,000,000
Loans, net of unearned income	721,713,000	664,834,000
Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 1,106,546,000	$ 972,966,000