Derivatives and Hedging Activities - Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax			$ 0.2	$ 0.0
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	$ 0.0	$ 0.0	0.2	0.0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0.0	0.0	0.2	0.0
Not Designated as Hedging Instrument
Derivative [Line Items]
Amount of net fee income recognized in other non-interest income	3.7	0.5	6.4	1.8
Amount of net (losses) gains recognized in mortgage banking revenues	(0.6)	$ 0.4	$ 4.4	$ 1.5
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	$ 0.0