Product Warranties (Tables)

6 Months Ended

Jun. 30, 2018

Product Warranties Disclosures [Abstract]

Changes in the Company's Accrual for Product Warranty Claims

Changes in the Company’s accrual for product warranty claims during the first six months of 2018 and 2017, including customer satisfaction settlements, were as follows:

(Thousands of dollars)
	2018			2017
Balance at January 1	$	151,425		$	34,419
Charges to expense	14,639			16,434
Settlements	(8,185		)	(16,698		)
Acquisition and other adjustments	(15,309		)	110,461
Balance at June 30	$	142,570		$	144,616