Restrictions on Cash and Due from Banks (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Restrictions on Cash and Due from Banks
Amount of minimum average reserve balances required to be maintained	$ 13.8	$ 9.1
Balances at the Federal Reserve Bank and other financial institutions	$ 109.4	$ 7.2

Amount of cash subject to withdrawal restrictions, restricted deposits held as compensating balances, and cash and securities segregated in compliance with regulations (such as cash deposited in a special reserve account for the exclusive benefit of customers).

No definition available.

Name:	us-gaap_CashAndSecuritiesSegregatedUnderFederalAndOtherRegulations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant