Derivatives - Narrative (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Replacement costs of contracts in a gain position	$ 2,400,000	$ 5,400,000
Additional balances in gross amounts not offset	$ 0	$ 0

The replacement cost of derivative contracts in a gain or asset position.

No definition available.

Name:	bgcg_DerivativeContractInGainPositionReplacementCost
Namespace Prefix:	bgcg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant