Fair Value of Financial Instruments - Unrealized Gains Included in Earnings Attributable to Level 3 Assets Held (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Unrealized Gains (Losses) [Line Items]
Unrealized gains included in earnings attributable to Level 3 assets still held	$ 63,647		$ 194,803		$ 304,707		$ 258,514
Unrealized gains attributable to noncontrolling interests	47,165		164,871		193,841		215,340
Equity warrant assets | Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Unrealized Gains (Losses) [Line Items]
Unrealized gains included in earnings attributable to Level 3 assets still held	6,911	[1]	14,205	[1]	17,777	[1]	19,788	[1]
Non-marketable securities | Fair value accounting
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Unrealized Gains (Losses) [Line Items]
Unrealized gains included in earnings attributable to Level 3 assets still held	56,736	[2]	180,598	[2]	286,930	[2]	238,726	[2]
Non-marketable securities | Fair value accounting | Venture capital and private equity fund investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Unrealized Gains (Losses) [Line Items]
Unrealized gains included in earnings attributable to Level 3 assets still held	57,967		32,694		207,885		89,705
Non-marketable securities | Fair value accounting | Other venture capital investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Unrealized Gains (Losses) [Line Items]
Unrealized gains included in earnings attributable to Level 3 assets still held	(1,231)		4,603		78		5,720
Non-marketable securities | Fair value accounting | Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Unrealized Gains (Losses) [Line Items]
Unrealized gains included in earnings attributable to Level 3 assets still held	$ 0		$ 143,301		$ 78,967		$ 143,301

[1] Unrealized gains (losses) are recorded in the line item “gains on derivative instruments, net”, a component of noninterest income.

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