Inventories Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventory Valuation Reserves		$ 162,800,000	$ 135,700,000
LIFO inventory amount		408,500,000	386,600,000
Replacement costs over stated LIFO value		$ 11,600,000	$ 10,900,000
Effect of LIFO inventory liquidation on income	$ 0