Derivative Financial Instruments and Hedging Activities - Schedule of Fair Value by Balance Sheet Location (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative Asset, Fair Value, Gross	$ 319.1	$ 326.1
Cash collateral	39.5	18.2
Derivative Asset, Fair Value, Gross, Total net of cash collateral	279.6	307.9
Derivative Liabilities, Fair Value, Gross	268.7	310.5
Cash collateral	49.7	38.6
Derivative Liabilities, Fair Value, Gross, Total net of cash collateral	219.0	271.9
Derivative Asset	165.8	155.8
Derivative Assets, Total net of cash collateral	126.3	137.6
Derivative Liabilities, Fair Value, Net	115.4	140.3
Derivative Liabilities, Total net of cash collateral	$ 65.7	$ 101.7