Composition of Loans, Net of Unearned Income, Broken Out by Portfolio Segment and Class of Financing Receivable (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	$ 6,970,082	[1]	$ 5,521,737	[1]
Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	6,274,944		4,967,210
Commercial loans | Software
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	2,492,849		1,820,680
Commercial loans | Hardware
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	952,303		641,052
Commercial loans | Venture capital/private equity
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	1,117,419		1,036,201
Commercial loans | Life science
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	863,737		575,944
Commercial loans | Premium wine
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	476,233		457,227
Commercial loans | Other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	372,403		436,106
Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	695,138		554,527
Consumer loans | Real estate secured loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	534,001		361,704
Consumer loans | Other
Financing Receivable, Recorded Investment [Line Items]
Loans, net of unearned income	$ 161,137		$ 192,823

[1] Included within our total loan portfolio are credit card loans of $49.7 million and $32.5 million at December 31, 2011 and 2010, respectively.