Debt - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($) class subsidiaryBusinessTrust
Debt Instrument [Line Items]
Number of classes of financial instruments | class	2
Number of business subsidiary trusts | subsidiaryBusinessTrust	2
Interest Rate Swap
Debt Instrument [Line Items]
Amount of hedged item	$ 20.0
ACST II | Junior Subordinated Debt, Preferred Securities | London Interbank Offered Rate
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	3.15%
ACST II | Junior Subordinated Debt, Preferred Securities | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	3.15%
ACST III | London Interbank Offered Rate
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	2.00%
ACST III | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	2.00%
Federal Reserve Bank Advances
Debt Instrument [Line Items]
Collateral, at carrying cost	$ 1,000.0
Collateral, at fair value	1,000.0
Federal Home Loan Bank of New York
Debt Instrument [Line Items]
Collateral, at carrying cost	1,000.0
Collateral, at fair value	$ 893.4