Variable Interest Entities (Narrative) (Detail) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014	Dec. 31, 2014 USD ($)
Variable Interest Entity [Line Items]
Carrying amounts of assets	$ 5,600		$ 5,000
Carrying amounts of liabilities	$ 5,400		4,800
Number of variable interest entities consolidated	1	0
Number of variable interest entities deconsolidated	1
Advisory Services [Member]
Variable Interest Entity [Line Items]
Carrying amounts of assets			751
Carrying amounts of liabilities			$ 754
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