Long Term Debt (Tables)

3 Months Ended

Mar. 31, 2017

Debt Disclosure [Abstract]

Components of Long-term Debt

The components of long-term debt as of the dates indicated below were as follows:

	March 31, 2017				December 31, 2016
			Unamortized				Unamortized
			Debt				Debt
			Issuance				Issuance
	Principal		Debt Cost		Principal		Debt Cost
	(Thousands of dollars)
Senior Notes issued March 17, 2014, interest only payable semi-annually at 5.25%, maturing March 15, 2019	$	500,000	$	2,441	$	500,000	$	2,753
Revolving Credit Facility due October 1, 2018 with a group of commercial banks, interest payable at variable rates		135,500		—		134,000		—
Total long-term debt	$	635,500	$	2,441	$	634,000	$	2,753