Additional Information about Level 3 Assets Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 679,960		$ 456,732		$ 547,608		$ 409,155
Total Realized and Unrealized Gains (Losses) Included in Income	57,454		15,817		152,047		33,847
Purchases	44,783		33,728		132,929		80,073
Sales	(15,762)		(5,700)		(47,402)		(14,359)
Issuances	2,876		2,543		10,058		5,312
Distributions and Other Settlements	(15,634)		(1,307)		(40,935)		(11,839)
Transfers Into Level 3
Transfers Out of Level 3			(10,809)		(628)		(11,185)
Ending Balance	753,677		491,004		753,677		491,004
Investment company fair value accounting | Venture capital and private equity fund investments | Non-marketable securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	515,118		322,159		391,247		271,316
Total Realized and Unrealized Gains (Losses) Included in Income	32,041		13,010		108,032		32,408
Purchases	42,590		31,873		119,990		73,718
Distributions and Other Settlements	(11,623)		(1,300)		(41,143)		(11,700)
Transfers Into Level 3
Ending Balance	578,126		365,742		578,126		365,742
Investment company fair value accounting | Other venture capital investments | Non-marketable securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	114,070		94,980		111,843		96,577
Total Realized and Unrealized Gains (Losses) Included in Income	17,237		(332)		22,608		(1,106)
Purchases	2,193		1,855		12,939		6,355
Sales	(9,335)		(1,177)		(27,513)		(6,500)
Distributions and Other Settlements	(4,005)				283
Transfers Into Level 3
Transfers Out of Level 3			(10,791)				(10,791)
Ending Balance	120,160		84,535		120,160		84,535
Investment company fair value accounting | Other investments | Non-marketable securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	995		960		981		1,143
Total Realized and Unrealized Gains (Losses) Included in Income	(16)		9		4		(43)
Distributions and Other Settlements	(6)		(7)		(12)		(138)
Transfers Into Level 3
Ending Balance	973		962		973		962
Investment company fair value accounting | Non-marketable securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	630,183	[1]	418,099	[1]	504,071	[1]	369,036	[1]
Total Realized and Unrealized Gains (Losses) Included in Income	49,262	[1]	12,687	[1]	130,644	[1]	31,259	[1]
Purchases	44,783	[1]	33,728	[1]	132,929	[1]	80,073	[1]
Sales	(9,335)	[1]	(1,177)	[1]	(27,513)	[1]	(6,500)	[1]
Distributions and Other Settlements	(15,634)	[1]	(1,307)	[1]	(40,872)	[1]	(11,838)	[1]
Transfers Into Level 3		[1]		[1]		[1]		[1]
Transfers Out of Level 3			(10,791)	[1]			(10,791)	[1]
Ending Balance	699,259	[1]	451,239	[1]	699,259	[1]	451,239	[1]
Equity warrant assets | Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	49,777	[2]	38,633	[2]	43,537	[2]	40,119	[2]
Total Realized and Unrealized Gains (Losses) Included in Income	8,192	[2]	3,130	[2]	21,403	[2]	2,588	[2]
Sales	(6,427)	[2]	(4,523)	[2]	(19,889)	[2]	(7,859)	[2]
Issuances	2,876	[2]	2,543	[2]	10,058	[2]	5,312	[2]
Distributions and Other Settlements					(63)	[2]	(1)	[2]
Transfers Into Level 3		[2]		[2]		[2]		[2]
Transfers Out of Level 3			(18)	[2]	(628)	[2]	(394)	[2]
Ending Balance	$ 54,418	[2]	$ 39,765	[2]	$ 54,418	[2]	$ 39,765	[2]

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

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