Deposits - Brokered Deposits (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Interest-bearing Domestic Deposit, Brokered	$ 1,480.0	$ 1,570.0
Money Market Funds [Member]
Interest-bearing Domestic Deposit, Brokered	538.2	370.4
Certificates of Deposit [Member]
Interest-bearing Domestic Deposit, Brokered	$ 940.5	$ 1,200.0