Fair Value Measurements - Fair Value of Direct and Indirect Investments, Related Unfunded Commitments and Financial Support Provided (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Indirect Investments [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	$ 9
Unfunded Commitments	1
Indirect Investments [Member] | Passive Funds [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	9
Unfunded Commitments	1
Principal Investments [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	375
Unfunded Commitments	57
Funded Commitments	2	2
Funded Other	1	1
Principal Investments [Member] | Indirect Investments [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	301
Unfunded Commitments	57
Funded Commitments	2	2
Principal Investments [Member] | Direct Investments [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair Value	74
Funded Other	$ 1	$ 1