Debt, Financing Arrangements, and Leases (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Long-term debt

Long-term debt, presented net of unamortized discount and unamortized debt issuance costs, consists of the following:

	December 31,
	2019			2018
	(Thousands of Dollars)
7.125% unsecured debentures due 2025	$	85,000		$	85,000
4.0% unsecured debentures due 2027	500,000			500,000
Debt issuance costs	(4,083		)	(4,507		)
Unamortized debt discount	(3,872		)	(4,325		)
Total long-term debt	$	577,045		$	576,168