Financial Instruments with Off-Balance Sheet Risk (Details) $ in Millions	Sep. 30, 2019 USD ($)
Entity Information [Line Items]
Credit extension commitments	$ 2,835.8
Unused Credit Card Lines
Entity Information [Line Items]
Credit extension commitments	746.0
Credit extension commitments beyond one year	1,238.4
Standby Letters of Credit
Entity Information [Line Items]
Credit extension commitments	$ 52.2