Summary of Fair Value by Strategy Type Alongside Consolidated Funds of Hedge Funds' Remaining Unfunded Commitments and Ability to Redeem Such Investments (Parenthetical) (Detail)	Dec. 31, 2016
Diversified Instruments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of investments unable to be redeemed at, or within 3 months of reporting date	4.00%
Percentage of investments side pocketed as of reporting date	96.00%
Credit Driven
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of investments unable to be redeemed at, or within 3 months of reporting date	44.00%
Percentage of investments redeemable as of reporting date	56.00%
Equity
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of investments unable to be redeemed at, or within 3 months of reporting date	100.00%
Commodities
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of investments unable to be redeemed at, or within 3 months of reporting date	100.00%