Federal funds purchased and securities sold under agreements to repurchase - Secured and Unsecured (Details) - Federal funds purchased $ in Millions	Dec. 31, 2021 USD ($)
Federal funds purchased and securities sold under agreements to repurchase
Maximum borrowing capacity of federal funds on unsecured basis	$ 60.0
Maximum borrowing capacity of federal funds on secured basis	$ 10.4

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_ShortTermDebtLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration