Derivatives - Offsetting of Derivative Instruments (Detail) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Offsetting Assets [Line Items]
Gross Amounts, derivative assets		$ 32,741	$ 42,252
Gross Amounts Offset, derivative assets		(29,404)	(41,321)
Net Amounts Presented in the Statements of Financial Condition, derivative assets	[1]	3,337	931
Gross Amounts, derivative liabilities		32,094	42,781
Gross Amounts Offset, derivative liabilities		(29,404)	(41,321)
Net Amounts Presented in the Statements of Financial Condition, derivative liabilities	[1]	2,690	1,460
FX/Commodities Options [Member]
Offsetting Assets [Line Items]
Gross Amounts, derivative assets			74
Net Amounts Presented in the Statements of Financial Condition, derivative assets	[1]		74
Gross Amounts, derivative liabilities		151
Net Amounts Presented in the Statements of Financial Condition, derivative liabilities	[1]	151
FX Swaps [Member]
Offsetting Assets [Line Items]
Gross Amounts, derivative assets		3,336	583
Gross Amounts Offset, derivative assets		(580)	(21)
Net Amounts Presented in the Statements of Financial Condition, derivative assets	[1]	2,756	562
Gross Amounts, derivative liabilities		2,107	340
Gross Amounts Offset, derivative liabilities		(580)	(21)
Net Amounts Presented in the Statements of Financial Condition, derivative liabilities	[1]	1,527	319
Forwards [Member]
Offsetting Assets [Line Items]
Gross Amounts, derivative assets		842	338
Gross Amounts Offset, derivative assets		(261)	(43)
Net Amounts Presented in the Statements of Financial Condition, derivative assets	[1]	581	295
Gross Amounts, derivative liabilities		792	258
Gross Amounts Offset, derivative liabilities		(261)	(43)
Net Amounts Presented in the Statements of Financial Condition, derivative liabilities	[1]	531	215
Futures [Member]
Offsetting Assets [Line Items]
Gross Amounts, derivative assets		28,563	41,257
Gross Amounts Offset, derivative assets		(28,563)	(41,257)
Gross Amounts, derivative liabilities		29,044	42,183
Gross Amounts Offset, derivative liabilities		(28,563)	(41,257)
Net Amounts Presented in the Statements of Financial Condition, derivative liabilities	[1]	$ 481	$ 926

[1] There were no additional balances in gross amounts not offset as of March 31, 2021 and December 31, 2020.