Derivatives and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)	May 01, 2020 USD ($)	Dec. 31, 2019 USD ($)
Derivative [Line Items]
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net	$ 0.0
Loss on Fair Value Hedge Ineffectiveness	$ 0.0
Document Period End Date	Sep. 30, 2020
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	$ 941.2		$ 571.0
Derivative Asset, Estimated Fair Value	68.3		23.2
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	1,078.9		631.2
Derivative Liabilities, Estimated Fair Value	63.1		22.2
Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	87.6		0.0
Derivative Asset, Estimated Fair Value	0.2		0.0
Not Designated as Hedging Instrument | Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	754.3		503.2
Derivative Asset, Estimated Fair Value	61.3		21.9
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	754.3		503.2
Derivative Liabilities, Estimated Fair Value	61.3		21.9
Not Designated as Hedging Instrument | Interest rate lock commitments
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	186.9		67.8
Derivative Asset, Estimated Fair Value	7.0		1.3
Not Designated as Hedging Instrument | Forward loan sales contracts
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	237.0		128.0
Derivative Liabilities, Estimated Fair Value	$ 1.6		$ 0.3
Interest rate swap contracts
Derivative [Line Items]
Derivative, Notional Amount, Contract 1		$ 46.4
Derivative, Notional Amount, Contract 2		36.1
Derivative, Notional Amount		$ 5.1
Derivative, Fixed Interest Rate, Contract 1		0.0040
Derivatives, Fixed Interest Rate, Contract 2		0.0034
Derivatives, Fixed Interest Rate, Contract 3		0.0040