Aging of Gross Loans, Broken out by Portfolio Segment and Class of Financing Receivable (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	$ 2,583	$ 1,243
60 - 89 Days Past Due	1,263	1,971
Greater Than 90 Days Past Due	1,373	7,849
Total Past Due	5,219	11,063
Current	6,025,747	5,556,142
Loans Past Due 90 Days or More Still Accruing Interest	2	44
Software | Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	311	674
60 - 89 Days Past Due	1,209	239
Greater Than 90 Days Past Due	1	17
Total Past Due	1,521	930
Current	2,080,138	1,834,897
Loans Past Due 90 Days or More Still Accruing Interest	1	17
Hardware | Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	54	89
60 - 89 Days Past Due		819
Greater Than 90 Days Past Due	1	27
Total Past Due	55	935
Current	755,963	642,786
Loans Past Due 90 Days or More Still Accruing Interest	1	27
Venture capital/private equity | Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,020,628	1,046,696
Life science | Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	165	157
Total Past Due	165	157
Current	651,183	578,208
Premium wine | Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	468,351	451,006
Other | Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	98
Total Past Due	98
Current	375,061	438,345
Commercial loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	628	920
60 - 89 Days Past Due	1,209	1,058
Greater Than 90 Days Past Due	2	44
Total Past Due	1,839	2,022
Current	5,351,324	4,991,938
Loans Past Due 90 Days or More Still Accruing Interest	2	44
Other | Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
60 - 89 Days Past Due	48
Total Past Due	48
Current	198,110	192,771
Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
60 - 89 Days Past Due	48
Total Past Due	48
Current	641,420	533,819
Consumer loans | Real estate secured loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	443,310	341,048
Total gross loans excluding impaired loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	628	920
60 - 89 Days Past Due	1,257	1,058
Greater Than 90 Days Past Due	2	44
Total Past Due	1,887	2,022
Current	5,992,744	5,525,757
Loans Past Due 90 Days or More Still Accruing Interest	2	44
Impaired loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 59 Days Past Due	1,955	323
60 - 89 Days Past Due	6	913
Greater Than 90 Days Past Due	1,371	7,805
Total Past Due	3,332	9,041
Current	$ 33,003	$ 30,385