Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Entity Information
Credit extension commitments	$ 2,807.8	$ 2,620.4
Unused credit card lines		1,058.5
Unused Credit Card Lines
Entity Information
Credit extension commitments	764.1	726.7
Unused credit card lines	1,212.7
Standby Letters of Credit
Entity Information
Credit extension commitments	$ 42.7	$ 46.7