Fair Value Disclosures - Investments in Certain Entities Calculate Net Asset Value per Share (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Unfunded Commitments	$ 152	$ 129
Equity Method, Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidation period, years	4 years	4 years
Total Unfunded Commitments	$ 67	$ 61
Equity Method, Private Equity Funds [Member] \| Assets of Consolidated VIEs, [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidation period, years		7 years
Total Unfunded Commitments		$ 22
Amount of unfunded commitments contractually obligated to fund		$ 31
Redemption period		1 year
Equity Method, Private Equity Funds [Member] \| Consolidated Variable Interest Entities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidation period, years	5 years
Total Unfunded Commitments	$ 19	$ 1
Amount of unfunded commitments contractually obligated to fund	$ 31
Equity Method, Hedge Funds/Funds of Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidation period, years	1 year	2 years
Total Unfunded Commitments	$ 33	$ 39
Equity Method, Hedge Funds/Funds of Hedge Funds [Member] \| Consolidated Variable Interest Entities [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Unfunded Commitments	0
Equity Method, Real Estate Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Unfunded Commitments	$ 28	$ 1
Redemption period	6 years	7 years