Other Comprehensive Income/Loss - Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Dec. 31, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	$ 3,358.5	$ 3,361.3	$ 3,447.0	$ 3,304.0
Net unrealized gain (loss) on derivatives	0.2		0.2
Change in net unrealized gain during period, pre-tax	(23.5)	70.7
Change in net unrealized gain during period, tax expense (benefit)	(5.8)	17.7
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	(17.7)	53.0
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), before Tax	0.1	0.0
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, tax expense (benefit)	0.0	0.0
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), after Tax	0.1	0.0
Unrealized loss on derivatives, tax expense (benefit)	0.0	0.3
Other comprehensive (loss) income, before tax	(23.4)	72.7
Other Comprehensive Income (Loss), tax expense (benefit)	(5.8)	18.3
Other Comprehensive Income (Loss), Net of Tax	(17.6)	54.4
Net unrealized loss on investment securities available-for-sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	(190.3)		(172.6)
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax	(5.6)		(5.7)
Net accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	$ (195.7)	$ (267.5)	$ (178.1)	$ (321.9)