Derivatives and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	$ 963.6	$ 901.6
Derivative Asset, Estimated Fair Value	45.1	55.3
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	1,564.1	1,014.1
Derivative Liabilities, Estimated Fair Value	43.3	53.3
Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	587.6	87.6
Derivative Asset, Estimated Fair Value	1.0	0.2
Not Designated as Hedging Instrument | Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	849.7	799.7
Derivative Asset, Estimated Fair Value	42.1	52.0
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	849.7	799.7
Derivative Liabilities, Estimated Fair Value	42.1	52.0
Not Designated as Hedging Instrument | Interest rate lock commitments
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	113.9	101.9
Derivative Asset, Estimated Fair Value	3.0	3.3
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	126.8	126.8
Derivative Liabilities, Estimated Fair Value	$ 0.2	$ 1.1