Regulatory Requirements and Subsidiary Dividend Restrictions - Customer Reserve Requirements (Details) - USD ($)	Oct. 04, 2021	Sep. 30, 2021
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		$ 7,400,000
Customer SRBA
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		1,000
PAB
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		10,500,000
PAB Reserve Requirement
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		3,100,000
PAB SRBA
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		$ 1,000
PAB SRBA | Subsequent Event
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required and made	$ 8,900,000