Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Long-term Debt

	December 31
(Thousands of dollars)	2013			2012
Notes payable
2.50% notes, due 2017	$	550,000			550,000
3.70% notes, due 2022		600,000			600,000
4.00% notes, due 2022		500,000			500,000
7.05% notes, due 2029		250,000			250,000
5.125% notes, due 2042		350,000			350,000
Notes payable to banks, 1.4375% at December 31, 2013		350,000			0
Other, 6%, due through 2028		0			1,169
Total notes payable		2,600,000			2,251,169
Unamortized discount on notes payable		(5,439	)		(5,922	)
Total notes payable, net of unamortized discount		2,594,561			2,245,247
Capitalized lease obligation, due through June 2028		368,251			0
Total debt including current maturities		2,962,812			2,245,247
Current maturities		(26,249	)		(46	)
Total long-term debt	$	2,936,563			2,245,201