Fair Value of Financial Instruments - Additional Information about Level 3 Assets Measured at Fair Value on a Recurring Basis (Detail) (USD $)	3 Months Ended																			3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Equity warrant assets Other assets		Mar. 31, 2013 Equity warrant assets Other assets		Mar. 31, 2014 Non-marketable securities Fair value accounting		Mar. 31, 2013 Non-marketable securities Fair value accounting		Mar. 31, 2014 Non-marketable securities Fair value accounting Venture capital and private equity fund investments	Mar. 31, 2013 Non-marketable securities Fair value accounting Venture capital and private equity fund investments	Mar. 31, 2014 Non-marketable securities Fair value accounting Other venture capital investments	Mar. 31, 2013 Non-marketable securities Fair value accounting Other venture capital investments	Mar. 31, 2013 Non-marketable securities Fair value accounting Other investments	Mar. 31, 2014 Level 3 Fair value accounting Other venture capital investments	Dec. 31, 2013 Level 3 Fair value accounting Other venture capital investments	Mar. 31, 2014 Level 3 Fair value accounting Other securities	Dec. 31, 2013 Level 3 Fair value accounting Other securities	Mar. 31, 2014 Fair Value, Measurements, Recurring Fair value accounting Other securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 1,314,951,000	$ 859,141,000	$ 99,891,000	[1]	$ 66,129,000	[1]	$ 1,215,060,000	[2]	$ 793,012,000	[2]	$ 862,972,000	$ 665,921,000	$ 32,839,000	$ 127,091,000	$ 0	$ 28,306,000	$ 32,839,000	$ 362,487,000	$ 319,249,000	$ 319,249,000	[3]
Total Realized and Unrealized Gains (Losses) Included in Income	(240,245,000)	(26,157,000)	(24,378,000)	[1]	(1,459,000)	[1]	(215,867,000)	[2]	(24,698,000)	[2]	(111,335,000)	(22,510,000)	(1,838,000)	(2,188,000)	0					(102,694,000)	[3]
Purchases	45,125,000	29,910,000	0	[1]	0	[1]	45,125,000	[2]	29,910,000	[2]	44,455,000	29,744,000	670,000	166,000	0					0	[3]
Sales	(90,347,000)	(2,271,000)	(39,993,000)	[1]	(2,250,000)	[1]	(50,354,000)	[2]	(21,000)	[2]	0	0	(3,514,000)	(21,000)	0					(46,840,000)	[3]
Issuances	3,417,000	1,926,000	3,417,000	[1]	1,926,000	[1]	0	[2]	0	[2]	0	0	0	0	0					0	[3]
Distributions and Other Settlements	(41,324,000)	(17,812,000)	626,000	[1]	364,000	[1]	(41,950,000)	[2]	(18,176,000)	[2]	(41,840,000)	(17,099,000)	(3,527,000)	(1,077,000)	0					3,417,000	[3]
Transfers Into Level 3	0	0	0	[1]	0	[1]	0	[2]	0	[2]	0	0	0	0	0					0	[3]
Transfers Out of Level 3	(16,710,000)	(5,143,000)	(677,000)	[1]	(1,582,000)	[1]	(16,033,000)	[2]	(3,561,000)	[2]	0	0	0	(3,561,000)	0
Ending Balance	1,455,357,000	891,908,000	87,642,000	[1]	66,046,000	[1]	1,367,715,000	[2]	825,862,000	[2]	976,922,000	701,076,000	28,306,000	124,786,000	0	28,306,000	32,839,000	362,487,000	319,249,000	362,487,000	[3]
Unrealized gain on securities	$ 351,000,000

[1] Realized and unrealized gains (losses) 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.

[3] Ending balance Includes total unrealized valuation gains of $351 million attributable to two of our portfolio companies, FireEye and Twitter.