Fair Value of Assets and Liabilities - Summary of Liabilities Recorded at Carrying Value (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Senior Notes	$ 400.0	$ 400.0
Senior Notes Fair Value	407.5	400.0
Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Senior Notes	700.0	700.0
Senior Notes Fair Value	764.8	778.8
Senior Notes Due 2025 EURO [Member]
Debt Instrument [Line Items]
Senior Notes	405.3	429.5
Senior Notes Fair Value	$ 438.7	$ 466.0