Variable Interest Entities (Narrative) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Variable Interest Entity [Line Items]
Carrying amounts of assets	$ 5,400	$ 5,000
Carrying amounts of liabilities	$ 5,100	$ 4,800
Number of variable interest entities consolidated	1	3
Advisory Services [Member]
Variable Interest Entity [Line Items]
Carrying amounts of assets		$ 751
Carrying amounts of liabilities		$ 754
Number of variable interest entities deconsolidated	3
Variable Interest Entity Primary Beneficiary [Member] | Advisory Services [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities consolidated		3
Variable Interest Entity Primary Beneficiary [Member] | Collateral Loan Obligations [Member]
Variable Interest Entity [Line Items]
Investments carried at fair value		$ 4