Capital Stock (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Capital Stock [Abstract]
Percent of stock owned by active and retired employees	100.00%
Percent of shares held in voting trust	83.00%
Common stock, stated value per share	$ 20.00		$ 20.00
Cash dividends	$ 9.7	$ 8.0
Preferred stock shares authorized	10,000,000
Preferred stock par or stated value per share (USD per share)	$ 0.01
Preferred stock outstanding (in shares)	0		0