Variable Interest Entities Reflects adoption of ASU 2015-12 - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Nonoperating gain (loss)	$ 58	$ 165	$ 305
Net income (loss) attributable to noncontrolling interests	7	(30)	19
Consolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Nonoperating gain (loss)	58	(41)	$ 0
Net income (loss) attributable to noncontrolling interests	6	(41)
Variable Interest Entity, Not Primary Beneficiary [Member] \| Sponsored Investment Products [Member]
Variable Interest Entity [Line Items]
Net assets of investments funds	$ 3,000
Variable Interest Entity, Not Primary Beneficiary [Member] \| Collective Trust [Member]
Variable Interest Entity [Line Items]
Net assets of investments funds		1,400,000
Variable Interest Entity, Not Primary Beneficiary [Member] \| Minimum [Member] \| Other Sponsored Investment Funds [Member]
Variable Interest Entity [Line Items]
Net assets of investments funds		1,700,000
Variable Interest Entity, Not Primary Beneficiary [Member] \| Maximum [Member] \| Other Sponsored Investment Funds [Member]
Variable Interest Entity [Line Items]
Net assets of investments funds		$ 1,800,000