Inventories (Summary Of Inventory) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Finished products - First-In, First-Out ("FIFO") basis	$ 145.8	$ 259.2
Less: Last-In, First-Out ("LIFO") reserve - finished products	(42.6)	(160.8)
Finished products - LIFO basis	103.2	98.4
Store merchandise for resale	133.8	123.0
Materials and supplies	6.5	6.2
Total inventories	$ 243.5	$ 227.6