Income Tax Matters - Income Tax (Provision) Benefit - (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Domestic	$ (8.8)	$ 0.9	$ 8.5	$ (9.6)
Foreign	0.4	(0.2)	(1.1)	(0.6)
Total	$ (8.4)	$ 0.7	$ 7.4	$ (10.2)