Securities - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Securities
Realized net gains from trading securities portfolio	$ 7.8	$ 7.6
Realized net gains (losses) from other securities	$ 0.0	0.0
Financial Instrument, Owned, Pledged Status [Extensible Enumeration]	Asset Pledged as Collateral		Asset Pledged as Collateral
Asset Pledged as Collateral
Securities
Carrying amount of securities pledged	$ 605.6		$ 563.9
Fair value of securities pledged	562.9		$ 520.0
Hilltop Broker-Dealers
Securities
Realized net gains from trading securities portfolio	$ 9.6	$ 32.7