Summary of Fair Value by Strategy Type Alongside Consolidated Funds of Hedge Funds' Remaining Unfunded Commitments and Ability to Redeem Such Investments (Parenthetical) (Detail)	Sep. 30, 2013
Diversified Instruments
Net Asset Value As Fair Value By Strategy [Line Items]
Percentage of investments unable to be redeemed at, or within 3 months of reporting date	59.00%
Percentage of investments in hedge funds in process of liquidation	34.00%
Percentage of investments side pocketed as of reporting date	21.00%
Percentage of investments redeemable as of reporting date	7.00%
Credit Driven
Net Asset Value As Fair Value By Strategy [Line Items]
Percentage of investments unable to be redeemed at, or within 3 months of reporting date	94.00%
Percentage of investments elected to side pocket	6.00%
Equity
Net Asset Value As Fair Value By Strategy [Line Items]
Percentage of investments unable to be redeemed at, or within 3 months of reporting date	76.00%
Percentage of investments in hedge funds in process of liquidation	1.00%
Percentage of investments side pocketed as of reporting date	1.00%
Percentage of investments under lock-up restrictions	16.00%
Percentage of investments subject to side pocket or gate	7.00%