Product Warranties (Tables)

3 Months Ended

Mar. 31, 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 three 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	6,260			5,117
Settlements	(7,516		)	(5,640		)
Balance at March 31	$	25,499		$	22,187