Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2018

Financial Instruments (Thousands of Dollars) [Abstract]

Schedule of Long-term Debt Instruments

	September 30, 2018				October 1, 2017				December 31, 2017
	Carrying		Fair		Carrying		Fair		Carrying		Fair
	Cost		Value		Cost		Value		Cost		Value
6.35% Notes Due 2040	$	500,000		546,450		500,000		613,750		500,000		601,800
3.50% Notes Due 2027		500,000		466,350		500,000		496,850		500,000		488,300
5.10% Notes Due 2044		300,000		285,390		300,000		324,300		300,000		313,320
3.15% Notes Due 2021		300,000		297,720		300,000		306,840		300,000		302,640
6.60% Debentures Due 2028		109,895		124,698		109,895		132,830		109,895		131,390
Total long-term debt	$	1,709,895		1,720,608		1,709,895		1,874,570		1,709,895		1,837,450
Less: Deferred debt expenses		15,174		-		16,634		-		16,286		-
Long-term debt	$	1,694,721		1,720,608		1,693,261		1,874,570		1,693,609		1,837,450