Incentive Plans - Changes in Stock Options Outstanding (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Exercised (in shares)	(2,657)	(181,655)	(32,554)
Stock Options
Number of Shares
Outstanding at beginning of year (in shares)	13,000	1,319,500	2,048,400
Exercised (in shares)	(11,000)	(760,500)	(170,000)
Forfeited (in shares)	(2,000)	(546,000)	(558,900)
Outstanding at end of year (in shares)	0	13,000	1,319,500
Exercisable at end of year (in shares)	0	13,000	1,319,500	2,048,400
Average Exercise Price
Outstanding at beginning of year (in USD per share)	$ 28.51	$ 37.77	$ 40.14
Exercised (in USD per share)	28.51	23.29	17.57
Forfeited (in USD per share)	28.51	49.65	52.61
Outstanding at end of year (in USD per share)	0	28.51	37.77
Exercisable at end of year (in USD per share)	$ 0	$ 28.51	$ 34.25	$ 37.88