Additional Information about Level 3 Assets Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 799,962		$ 547,608		$ 409,155
Total Realized and Unrealized Gains (Losses) Included in Income	(104,712)		(176,940)		(67,245)
Purchases	135,361		170,479		120,033
Sales	(30,793)		(53,047)		(15,311)
Issuances	11,978		13,849		7,781
Distributions and Other Settlements	(153,068)		(55,150)		(29,817)
Transfers Into Level 3	0		0		0
Transfers Out of Level 3	(9,011)		(717)		(11,478)
Ending Balance	859,141		799,962		547,608
Equity Warrant Asset | Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial Instruments Fair Value Assumptions Weighted Average Remaining Life	45.00%		40.00%
Fair Value Inputs, Discount for Lack of Marketability	22.50%		15.00%
Beginning Balance	63,030	[1]	43,537	[1]	40,119
Total Realized and Unrealized Gains (Losses) Included in Income	(13,697)		(31,958)		(4,922)
Purchases	0		0		0
Sales	(21,077)		(25,534)		(8,538)
Issuances	11,978		13,849		7,781
Distributions and Other Settlements	(78)		(63)		(60)
Transfers Into Level 3	0		0		0
Transfers Out of Level 3	(1,421)		(717)		(687)
Ending Balance	66,129	[1]	63,030	[1]	43,537	[1]
Fair value accounting | Other venture capital investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Ending Balance	127,091
Non-marketable securities | Fair value accounting
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	736,932	[2]	504,071	[2]	369,036	[2]
Total Realized and Unrealized Gains (Losses) Included in Income	(91,015)	[2]	(144,982)	[2]	(62,323)	[2]
Purchases	135,361	[2]	170,479	[2]	120,033	[2]
Sales	(9,716)	[2]	(27,513)	[2]	(6,773)	[2]
Issuances	0		0		0
Distributions and Other Settlements	(152,990)	[2]	(55,087)	[2]	(29,757)	[2]
Transfers Into Level 3	0		0		0
Transfers Out of Level 3	(7,590)	[2]	0	[2]	(10,791)	[2]
Ending Balance	793,012	[2]	736,932	[2]	504,071	[2]
Non-marketable securities | Fair value accounting | Venture capital and private equity fund investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	611,824		391,247		271,316
Total Realized and Unrealized Gains (Losses) Included in Income	(44,283)		(119,164)		(43,645)
Purchases	122,238		156,498		105,899
Sales	0		0		0
Issuances	0		0		0
Distributions and Other Settlements	(112,424)		(55,085)		(29,613)
Transfers Into Level 3	0		0		0
Transfers Out of Level 3	0		0		0
Ending Balance	665,921		611,824		391,247
Non-marketable securities | Fair value accounting | Other venture capital investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	124,121		111,843		96,577
Total Realized and Unrealized Gains (Losses) Included in Income	(46,711)		(25,794)		(18,696)
Purchases	13,123		13,981		14,134
Sales	(9,716)		(27,513)		(6,773)
Issuances	0		0		0
Distributions and Other Settlements	(39,558)		16		0
Transfers Into Level 3	0		0		0
Transfers Out of Level 3	(7,590)		0		(10,791)
Ending Balance	127,091		124,121		111,843
Non-marketable securities | Fair value accounting | Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	987		981		1,143
Total Realized and Unrealized Gains (Losses) Included in Income	(21)		(24)		18
Purchases	0		0		0
Sales	0		0		0
Issuances	0		0		0
Distributions and Other Settlements	(1,008)		(18)		(144)
Transfers Into Level 3	0		0		0
Transfers Out of Level 3	0		0		0
Ending Balance	$ 0		$ 987		$ 981

[1] Realized and unrealized gains are recorded on the line item “gains on derivative instruments, net”, a component of noninterest income.

[2] Realized and unrealized gains (losses) are recorded on the line items “gains on investment securities, net”, and “other noninterest income”, components of noninterest income.