Fair Value of Assets and Liabilities - Summary of Liabilities Recorded at Carrying Value (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Senior Notes	$ 400.0	$ 400.0
Senior Notes Fair Value	363.2	387.0
Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Senior Notes	700.0	0.0
Senior Notes Fair Value	735.9	0.0
Senior Notes Due 2025 EURO [Member]
Debt Instrument [Line Items]
Senior Notes	409.8	0.0
Senior Notes Fair Value	$ 421.4	$ 0.0