Financing Arrangements and Debt (Tables)

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Schedule of Long-term Debt

Long-term debt consisted of the following as of December 31, 2021 and 2020:

	December 31,
(Thousands of dollars)	2021		2020
Notes payable
4.00% notes, due June 2022	$	—	259,291
4.95% notes, due December 2022 ¹	—		317,067
6.875% notes, due August 2024	242,428		542,428
5.75% notes, due August 2025	548,675		548,675
5.875% notes, due December 2027	543,249		543,249
6.375% notes, due July 2028	550,000		—
7.05% notes, due May 2029	250,000		250,000
6.375% notes, due December 2042 ¹	349,000		349,000
Total notes payable	2,483,352		2,809,710
Unamortized debt issuance cost and discount on notes payable	(22,773)		(21,643)
Total notes payable, net of unamortized discount	2,460,579		2,788,067
Capitalized lease obligation, due through March 2029 ¹	5,489		—
Total debt including current maturities	2,466,068		2,788,067
Senior Unsecured Revolving Credit Facility	—		200,000
Current maturities	(654)		—
Total long-term debt	$	2,465,414	2,988,067

1 Coupon rate may fluctuate 25 basis points if rating is periodically downgraded or upgraded by S&P and Moody’s.