Derivatives and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	$ 897.2	$ 571.0
Derivative Asset, Estimated Fair Value	65.1	23.2
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	913.2	631.2
Derivative Liabilities, Estimated Fair Value	59.5	22.2
Not Designated as Hedging Instrument | Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	536.0	503.2
Derivative Asset, Estimated Fair Value	57.4	21.9
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	536.0	503.2
Derivative Liabilities, Estimated Fair Value	57.4	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	361.2	67.8
Derivative Asset, Estimated Fair Value	7.7	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	377.2	128.0
Derivative Liabilities, Estimated Fair Value	$ 2.1	$ 0.3