Other Assets - Seed Capital and Private Equity Investments Valued Using Net Asset Value (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Fair value	$ 319		$ 342
Unfunded commitments	56		45
Seed capital and other funds
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Fair value	292	[1]	307	[1]
Unfunded commitments	0	[1]	0	[1]
Redemption frequency	Daily-quarterly	[1]	Daily-quarterly	[1]
Private equity investments
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Fair value	27	[2],[3]	35	[2],[3]
Unfunded commitments	56	[2],[3]	45	[2],[3]
Small Business Investment Company
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Fair value	24	[2],[3]	18	[2],[3]
Unfunded commitments	$ 56	[2],[3]	$ 45	[2],[3]
Minimum | Seed capital and other funds
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Redemption notice period	0 days	[1]	0 days	[1]
Maximum | Seed capital and other funds
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]
Redemption notice period	180 days	[1]	180 days	[1]

[1] Other funds include various leveraged loans, hedge funds and structured credit funds. Redemption notice periods vary by fund.

[2] Includes investments and unfunded commitments related to SBICs, which are compliant with the Volcker Rule, of $24 million and $56 million, respectively, at March 31, 2015 and $18 million and $45 million, respectively, at Dec. 31, 2014.

[3] Private equity funds primarily include numerous venture capital funds that invest in various sectors of the economy. Private equity funds do not have redemption rights. Distributions from such funds will be received as the underlying investments in the funds are liquidated.