Revenue Recognition (Deferred Revenue) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue Recognition [Abstract]
Balance at beginning of period	$ 111.1	$ 108.3	$ 89.1
New contracts sold	49.1	49.1	55.0
Balance at end of period	110.3	111.1	108.3
Deferred Revenue, Revenue Recognized	(49.9)	(46.3)	$ (35.8)
Deferred Revenue, Current	35.3	35.5
Deferred Revenue, Noncurrent	$ 75.0	$ 75.6