Loans and Allowance for Loan Losses - Composition of Loans, Net of Unearned income (Parenthetical) (Detail) (USD $)	Sep. 30, 2014		Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 12,017,181,000	[1]	$ 10,906,386,000	[1]
Credit Card Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan portfolio	122,000,000		85,000,000
Real estate secured loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,047,935,000		873,255,000
Real estate secured loans | Loans for personal residence
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	860,024,000		685,327,000
Real estate secured loans | Loans to eligible employees
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	129,979,000		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	57,932,000		66,380,000
Premium wine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross construction loans	111,000,000		112,000,000
Loans, net of unearned income	$ 749,568,000		$ 664,834,000

[1] Included within our total loan portfolio are credit card loans of $122 million and $85 million at September 30, 2014 and December 31, 2013, respectively.