Composition of Loans, Net of Unearned income (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 8,192,369	[1]	$ 6,970,082	[1]
Real estate secured loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	989,207		879,989
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	752,976		695,138
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7,439,393		6,274,944
Commercial Portfolio Segment [Member] | Commercial Loans Receivable excluding Construction and Real Estate Secured [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	7,010,998		5,898,700
Consumer Other Financing Receivable | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	143,606		161,137
Real estate secured loans | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	609,370	[2]	534,001	[2]
Software | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,952,866		2,492,849
Hardware | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,192,716		952,303
Venture capital/private equity | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,393,943		1,117,419
Life science | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,027,693		863,737
Premium wine | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	513,647		476,233
Premium wine | Commercial Portfolio Segment [Member] | Non-real Estate Secured Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	133,810		130,245
Premium wine | Commercial Portfolio Segment [Member] | Real Estate Secured Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	379,837	[3]	345,988	[3]
Commercial Other Financing Receivable | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	358,528		372,403
Commercial Other Financing Receivable | Commercial Portfolio Segment [Member] | Construction Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	48,558		30,256
Commercial Other Financing Receivable | Commercial Portfolio Segment [Member] | Commercial Loans Receivable excluding Construction and Real Estate Secured [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 309,970		$ 342,147

[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:

[3] Included in our premium wine portfolio are gross construction loans of $148.4 million and $110.8 million at September 30, 2012 and December 31, 2011, respectively.