Income Tax Matters - Income Tax Benefit (Provision) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Domestic	$ 16.7	$ (1.0)	$ 17.3	$ (10.6)
Foreign	(1.2)	(0.3)	(1.5)	(0.3)
Total	$ 15.5	$ (1.3)	$ 15.8	$ (10.9)