Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value of Financial Instruments (Thousands of Dollars) [Abstract]

Fair Value Hierarchy

	Fair Value Measurements Using:
			Quoted
			Prices in
			Active
			Markets		Significant
			for		Other		Significant
			Identical		Observable		Unobservable
	Fair		Assets		Inputs		Inputs
	Value		(Level 1)		(Level 2)		(Level 3)
September 30, 2018
Assets:
Available-for-sale securities	$	2,346		2,346		-		-
Derivatives		20,079		-		20,079		-
Total assets	$	22,425		2,346		20,079		-
Liabilities:
Derivatives	$	2,113		-		2,113		-
Option agreement		23,460		-		-		23,460
Total liabilities	$	25,573		-		2,113		23,460
October 1, 2017
Assets:
Available-for-sale securities	$	2,866		2,866		-		-
Derivatives		11,975		-		11,975		-
Total assets	$	14,841		2,866		11,975		-
Liabilities:
Derivatives	$	22,671		-		22,671		-
Option agreement		28,510		-		-		28,510
Total liabilities	$	51,181		-		22,671		28,510
December 31, 2017
Assets:
Available-for-sale securities	$	3,126		3,126		-		-
Derivatives		12,226		-		12,226		-
Total assets	$	15,352		3,126		12,226		-
Liabilities:
Derivatives	$	23,051		-		23,051		-
Option agreement		23,980		-		-		23,980
Total Liabilities	$	47,031		-		23,051		23,980

Reconciliation of Level 3 Fair Value

	2018		2017
Balance at beginning of year	$	(23,980)		(28,770)
Gain from change in fair value		520		260
Balance at end of third quarter	$	(23,460)		(28,510)