Income Taxes (Provision for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current:
Federal	$ 234.9	$ 71.7	$ 46.1
State	67.3	43.6	40.5
Deferred:
Federal	(34.1)	65.4	151.8
State	18.6	12.6	18.9
State deferred benefit - change in valuation allowance	0.0	(17.2)	(4.6)
Uncertain tax positions and interest, and other	(3.9)	(3.0)	(30.7)
Provision for income taxes	$ 282.8	$ 173.1	$ 222.0