Capital Stock (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Class of Stock [Line Items]
Percent of stock owned by active and retired employees	100.00%
Common stock stated value per share	$ 20.00		$ 20.00
Cash dividends	$ 7.0	$ 6.9
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
2017 Voting Trust | Common Stock
Class of Stock [Line Items]
Percent of shares held in voting trust	83.00%