Summary of Significant Accounting and Reporting Policies - Other Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) item	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 31, 2020 USD ($)	Jun. 22, 2015	Apr. 30, 2015 USD ($)	Apr. 09, 2015
Broker-Dealer
Debt Instrument
Number of primary lines of business | item	4
Banking
Debt Instrument
Number of primary lines of business | item	3
Interest Expense
Debt Instrument
Debt issuance costs amortized	$ 0.5	$ 0.5	$ 0.4
Senior Notes due April 2025
Debt Instrument
Interest rate (as a percent)					5.00%
Senior Notes due April 2025 | Private Placement
Debt Instrument
Capitalized debt issuance costs						$ 1.9
Interest rate (as a percent)							5.00%
Subordinated Debt
Debt Instrument
Capitalized debt issuance costs				$ 3.2