Earnings per Share (Narrative) (Details) - USD ($)				12 Months Ended
	Feb. 09, 2024	Dec. 30, 2022	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Aug. 31, 2022	Aug. 30, 2018
Earnings per Share [Line Items]
Total anti-dilutive shares excluded from the calculation (in shares)				17,900	119,000	48,600
Number of shares repurchased, cost				$ 25,011,000	$ 54,549,000
Unsettled repurchase shares				0	0
Retained percentage limit on value of TRS				20.00%
2018 Repurchase Program [Member]
Earnings per Share [Line Items]
Number of shares repurchased					103,010	0
Number of shares repurchased, cost					$ 4,500,000
2022 Repurchase Program [Member]
Earnings per Share [Line Items]
Number of shares repurchased				556,115	1,096,283
Number of shares repurchased, cost				$ 25,000,000	$ 50,000,000
Stock repurchase program, remaining amount				125,000,000
Deltic [Member] | Special Dividend [Member]
Earnings per Share [Line Items]
Dividend payable		$ 75,700,000	$ 276,300,000	$ 0		$ 276,300,000
Dividend payable, per share		$ 0.95	$ 4			$ 4
Distribution, payable date		Dec. 30, 2022	Dec. 31, 2021
Deltic [Member] | Subsequent Event [Member]
Earnings per Share [Line Items]
Dividend payable, per share	$ 0.45
Distribution, date of declared	Feb. 09, 2024
Distribution, date of record	Mar. 08, 2024
Distribution, payable date	Mar. 29, 2024
Maximum [Member] | 2018 Repurchase Program [Member]
Earnings per Share [Line Items]
Stock repurchase program, authorized amount								$ 100,000,000.0
Maximum [Member] | 2022 Repurchase Program [Member]
Earnings per Share [Line Items]
Stock repurchase program, authorized amount							$ 200,000,000