Derivatives - Offsetting of Derivative Instruments (Detail) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Offsetting Assets [Line Items]
Gross Amounts, Assets	$ 121,336,000	$ 42,252,000
Gross Amounts Offset, Assets	(117,167,000)	(41,321,000)
Net Amounts Presented in the Statements of Financial Condition, Assets	4,169,000	931,000
Gross Amounts, Liabilities	123,632,000	42,781,000
Gross Amounts Offset, Liabilities	(117,167,000)	(41,321,000)
Net Amounts Presented in the Statements of Financial Condition, Liabilities	6,465,000	1,460,000
Additional balance in gross amounts not offset	0	0
FX/commodities options
Offsetting Assets [Line Items]
Gross Amounts, Assets		74,000
Gross Amounts Offset, Assets		0
Net Amounts Presented in the Statements of Financial Condition, Assets		74,000
FX swaps
Offsetting Assets [Line Items]
Gross Amounts, Assets	4,545,000	583,000
Gross Amounts Offset, Assets	(622,000)	(21,000)
Net Amounts Presented in the Statements of Financial Condition, Assets	3,923,000	562,000
Gross Amounts, Liabilities	4,814,000	340,000
Gross Amounts Offset, Liabilities	(622,000)	(21,000)
Net Amounts Presented in the Statements of Financial Condition, Liabilities	4,192,000	319,000
Forwards
Offsetting Assets [Line Items]
Gross Amounts, Assets	364,000	338,000
Gross Amounts Offset, Assets	(118,000)	(43,000)
Net Amounts Presented in the Statements of Financial Condition, Assets	246,000	295,000
Gross Amounts, Liabilities	1,177,000	258,000
Gross Amounts Offset, Liabilities	(118,000)	(43,000)
Net Amounts Presented in the Statements of Financial Condition, Liabilities	1,059,000	215,000
Futures
Offsetting Assets [Line Items]
Gross Amounts, Assets	116,427,000	41,257,000
Gross Amounts Offset, Assets	(116,427,000)	(41,257,000)
Net Amounts Presented in the Statements of Financial Condition, Assets	0	0
Gross Amounts, Liabilities	117,641,000	42,183,000
Gross Amounts Offset, Liabilities	(116,427,000)	(41,257,000)
Net Amounts Presented in the Statements of Financial Condition, Liabilities	$ 1,214,000	$ 926,000