Product Warranties (Tables)

6 Months Ended

Jun. 30, 2014

Product Warranties Disclosures [Abstract]

Company's accrual for product warranty claims

Changes in the Company’s accrual for product warranty claims during the first six months of 2014 and 2013, including customer satisfaction settlements, were as follows:

(Thousands of dollars)
	2014			2013
Balance at January 1	$	26,755		$	22,710
Charges to expense	14,446			11,031
Settlements	(16,351		)	(12,134		)
Balance at June 30	$	24,850		$	21,607