Fair Value Measurements - Fair Value of Direct and Indirect Investments, Related Unfunded Commitments and Financial Support Provided (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Indirect Investments [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	$ 8		$ 8
Unfunded Commitments	1		1
Indirect Investments [Member] | Passive Funds [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	8		8
Unfunded Commitments	1		1
Principal Investments [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	224		224
Unfunded Commitments	44		44
Funded Commitments	2	$ 3	3	$ 5
Funded Other			13	2
Principal Investments [Member] | Indirect Investments [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	184		184
Unfunded Commitments	44		44
Funded Commitments	2	$ 3	3	5
Principal Investments [Member] | Direct Investments [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	$ 40		40
Funded Other			$ 13	$ 2