Acquisitions - Schedule of Acquired Loans with Credit Impairment (Details) $ in Millions	Feb. 01, 2022 USD ($)
Business Acquisition [Line Items]
Purchase Price (Initial Fair Value)	$ 623.3
Allowance for loans losses	298.2
Great Western Bank
Business Combination and Asset Acquisition [Abstract]
Contractually required principal and interest payments	979.2
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Other-than-Temporary Impairment Charges, Credit Loss	(238.7)
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Acquired, at Acquisition, at Fair Value	722.4
Interest component of cash flows expected to be collected (“accretable discount”)	(69.2)
Contractual cash flows not expected to be collected (“non-accretable discount”)	(29.9)
Purchase Price (Initial Fair Value)	623.3
Allowance for loans losses	59.5
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	682.8
Contractually required principal and interest payments	7,107.9
Loans Acquired in Transfer, Accretable Yield	(76.5)
Contractual cash flows not expected to be collected	(9.2)
Loans Acquired in Transfer at Acquisition Fair Value	7,022.2
Loans Acquired in Transfer, Amortized cost basis	$ 7,705.0