Loans and Allowance for Loan Losses - Activity in Allowance for Loan Losses Broken out by Portfolio Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 110,651	$ 89,947
Charge-offs	(5,626)	(6,990)
Recoveries	1,367	3,436
Provision for (Reduction of) Loan Losses	5,813	14,529
Ending Balance	112,205	100,922
Commercial loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	103,413	82,366
Charge-offs	(5,626)	(6,990)
Recoveries	987	3,207
Provision for (Reduction of) Loan Losses	6,207	13,236
Ending Balance	104,981	91,819
Commercial loans \| Software
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	42,648	38,263
Charge-offs	(1,518)	(859)
Recoveries	242	2,759
Provision for (Reduction of) Loan Losses	3,638	(4,738)
Ending Balance	45,010	35,425
Commercial loans \| Hardware
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	29,761	16,810
Charge-offs	(1,997)	(3,848)
Recoveries	446	105
Provision for (Reduction of) Loan Losses	(341)	17,281
Ending Balance	27,869	30,348
Commercial loans \| Venture capital/private equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	9,963	7,319
Charge-offs	0	0
Recoveries	0	0
Provision for (Reduction of) Loan Losses	519	(105)
Ending Balance	10,482	7,214
Commercial loans \| Life science
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	13,606	10,243
Charge-offs	(2,070)	(113)
Recoveries	203	221
Provision for (Reduction of) Loan Losses	2,207	(59)
Ending Balance	13,946	10,292
Commercial loans \| Premium wine
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	3,523	3,914
Charge-offs	0	0
Recoveries	90	78
Provision for (Reduction of) Loan Losses	86	(254)
Ending Balance	3,699	3,738
Commercial loans \| Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	3,912	5,817
Charge-offs	(41)	(2,170)
Recoveries	6	44
Provision for (Reduction of) Loan Losses	98	1,111
Ending Balance	3,975	4,802
Consumer loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	7,238	7,581
Charge-offs	0	0
Recoveries	380	229
Provision for (Reduction of) Loan Losses	(394)	1,293
Ending Balance	$ 7,224	$ 9,103

Reflects the amount of loans and leases that have been removed, or charged off, from both loan receivables and the reserve for credit losses, typically because they are considered to be not salvageable or have been purchased by unconsolidated collection entities.

+ References+ Details

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 8, 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Section 563c.102

-Paragraph 8

-Subparagraph a(ii)

-Chapter V

-Subsection I

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

+ Details