Related Party Transactions - Clearing Capital Agreement with Cantor (Details) - Related Party - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Related Party Transaction [Line Items]
Cash and collateral posted expense	$ 0.8	$ 1.4	$ 3.1	$ 3.3
Collateral already posted, aggregate fair value	$ 66.9		$ 66.9		$ 124.6