Components of Gains and Losses (Realized and Unrealized) on Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	$ 242,226		$ 138,770		$ 42,816
Gross losses on investment securities	(47,192)		(45,410)		(74,025)
Gains (losses) on investment securities, net	195,034		93,360		(31,209)
Gains (losses) attributable to noncontrolling interests, including carried interest	125,042		52,586		(26,638)
Available-for-sale Securities
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	37,387	[1]	27,110	[1]	246	[1]
Gross losses on investment securities	(261)	[1]	(2,287)	[1]	(414)	[1]
Marketable Securities | Fair value accounting
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	912		8,160		1,413
Gross losses on investment securities	(8,103)		(9,855)		(431)
Non-marketable securities | Fair value accounting | Venture capital and private equity fund investments
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	145,892		63,137		17,425
Gross losses on investment securities	(26,591)		(19,497)		(46,318)
Non-marketable securities | Fair value accounting | Other venture capital investments
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	36,506		29,455		15,970
Gross losses on investment securities	(8,918)		(11,079)		(18,678)
Non-marketable securities | Fair value accounting | Other investments
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	40		140		762
Gross losses on investment securities	(16)		(158)
Non-marketable securities | Equity method accounting | Other investments
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	12,445		8,551		6,528
Gross losses on investment securities	(2,241)		(616)		(3,337)
Non-marketable securities | Cost method accounting | Venture capital and private equity fund investments
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	2,517		1,739		449
Gross losses on investment securities	(1,028)		(1,793)		(4,439)
Non-marketable securities | Cost method accounting | Other investments
Gain (Loss) on Investments [Line Items]
Gross gains on investment securities	6,527		478		23
Gross losses on investment securities	$ (34)		$ (125)		$ (408)

[1] The cost basis of available-for-sale securities sold is determined on a specific identification basis.