Regulatory Requirements and Subsidiary Dividend Restrictions - Customer Reserve Requirements (Details) - USD ($) $ in Millions	Oct. 03, 2023	Sep. 30, 2023
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		$ 4.3
Customer SRBA
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		13.8
Customer SRBA | Subsequent Event
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit made	$ 3.7
PAB
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		6.9
PAB Reserve Requirement
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		6.9
PAB SRBA
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		$ 4.2