CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale, Amortized Cost	$ 6,529.2	$ 4,586.4
Debt Securities, Held-to-maturity, Fair Value	$ 1,012.7	$ 611.8
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	106,567,407	103,013,290
Treasury Stock, Value	$ 84.2	$ 71.1