Derivatives - Summary of Gains and (Losses) on Derivative Contracts (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss), net on derivative contract	$ 3,072	$ 3,253	$ 4,859	$ 8,044
FX/Commodities Options [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss), net on derivative contract	143	49	198	112
FX Swaps [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss), net on derivative contract	89	631	325	1,224
Equity Options [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss), net on derivative contract		318		318
Futures [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss), net on derivative contract	2,724	4,561	5,488	8,809
Forwards [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss), net on derivative contract	$ 116	$ (2,306)	$ (1,152)	$ (2,419)