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, 2011		Dec. 31, 2010		Dec. 31, 2009
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 547,608		$ 409,155		$ 368,335
Total Realized and Unrealized Gains (Losses) Included in Income	176,940		67,245		(32,014)
Purchases	170,479		120,033		88,213
Sales	(53,047)		(15,311)		(5,806)
Issuances	13,849		7,781		4,954
Distributions and Other Settlements	(55,150)		(29,817)		(14,316)
Transfers Into Level 3
Transfers Out of Level 3	(717)		(11,478)		(211)
Ending Balance	799,962		547,608		409,155
Equity Warrant Asset | Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	43,537	[1]	40,119	[1]	41,699	[1]
Total Realized and Unrealized Gains (Losses) Included in Income	31,958	[1]	4,922	[1]	(2,115)	[1]
Sales	(25,534)	[1]	(8,538)	[1]	(4,193)	[1]
Issuances	13,849	[1]	7,781	[1]	4,954	[1]
Distributions and Other Settlements	(63)	[1]	(60)	[1]	(15)	[1]
Transfers Into Level 3		[1]		[1]		[1]
Transfers Out of Level 3	(717)	[1]	(687)	[1]	(211)	[1]
Ending Balance	63,030	[1]	43,537	[1]	40,119	[1]
Non-marketable securities | Fair value accounting
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	504,071	[2]	369,036	[2]	326,636	[2]
Total Realized and Unrealized Gains (Losses) Included in Income	144,982	[2]	62,323	[2]	(29,899)	[2]
Purchases	170,479	[2]	120,033	[2]	88,213	[2]
Sales	(27,513)	[2]	(6,773)	[2]	(1,613)	[2]
Distributions and Other Settlements	(55,087)	[2]	(29,757)	[2]	(14,301)	[2]
Transfers Into Level 3		[2]		[2]		[2]
Transfers Out of Level 3			(10,791)	[2]
Ending Balance	736,932	[2]	504,071	[2]	369,036	[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	391,247		271,316		242,645
Total Realized and Unrealized Gains (Losses) Included in Income	119,164		43,645		(28,893)
Purchases	156,498		105,899		70,699
Distributions and Other Settlements	(55,085)		(29,613)		(13,135)
Transfers Into Level 3
Ending Balance	611,824		391,247		271,316
Non-marketable securities | Fair value accounting | Other venture capital investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	111,843		96,577		82,444
Total Realized and Unrealized Gains (Losses) Included in Income	25,794		18,696		(1,768)
Purchases	13,981		14,134		17,514
Sales	(27,513)		(6,773)		(1,613)
Distributions and Other Settlements	16
Transfers Into Level 3
Transfers Out of Level 3			(10,791)
Ending Balance	124,121		111,843		96,577
Non-marketable securities | Fair value accounting | Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	981		1,143		1,547
Total Realized and Unrealized Gains (Losses) Included in Income	24		(18)		762
Distributions and Other Settlements	(18)		(144)		(1,166)
Transfers Into Level 3
Ending Balance	$ 987		$ 981		$ 1,143

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

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