Credit Quality Indicators, Broken out by Portfolio Segment and Class of Financing Receivables (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	$ 6,030,966	$ 5,567,205
Software | Pass | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	1,875,198	1,717,309
Hardware | Pass | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	647,219	575,401
Venture capital/private equity | Pass | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	1,018,711	1,031,373
Life science | Pass | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	568,069	520,596
Premium wine | Pass | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	425,555	400,519
Other | Pass | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	353,076	415,381
Other | Pass | Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	185,829	181,561
Pass
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	5,509,520	5,179,227
Pass | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	4,887,828	4,660,579
Pass | Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	621,692	518,648
Pass | Consumer loans | Real estate secured loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	435,863	337,087
Software | Performing (Criticized) | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	206,461	118,518
Hardware | Performing (Criticized) | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	108,799	68,320
Venture capital/private equity | Performing (Criticized) | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	1,917	15,323
Life science | Performing (Criticized) | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	83,279	57,769
Premium wine | Performing (Criticized) | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	42,796	50,487
Other | Performing (Criticized) | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	22,083	22,964
Other | Performing (Criticized) | Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	12,329	11,210
Performing (Criticized)
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	485,111	348,552
Performing (Criticized) | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	465,335	333,381
Performing (Criticized) | Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	19,776	15,171
Performing (Criticized) | Consumer loans | Real estate secured loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	7,447	3,961
Software | Impaired | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	2,339	3,292
Hardware | Impaired | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	6,543	3,824
Life science | Impaired | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	1,038	3,412
Premium wine | Impaired | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	1,352	6,162
Other | Impaired | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	5,582	2,177
Impaired
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	36,335	39,426
Impaired | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	16,854	18,867
Impaired | Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	19,481	20,559
Impaired | Consumer loans | Real estate secured loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	19,481	20,559
Software | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	2,083,998	1,839,119
Hardware | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	762,561	647,545
Venture capital/private equity | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	1,020,628	1,046,696
Life science | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	652,386	581,777
Premium wine | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	469,703	457,168
Other | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	380,741	440,522
Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	5,370,017	5,012,827
Other | Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	198,158	192,771
Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	660,949	554,378
Consumer loans | Real estate secured loans
Financing Receivable, Recorded Investment [Line Items]
Financing receivable	$ 462,791	$ 361,607