Receivables (Tables)

12 Months Ended

Dec. 31, 2012

Receivables [Abstract]

Summary of the Company's receivable balances

The following is a summary of the Company's receivable balances at December 31:

(Thousands of dollars)	2012			2011
Accounts receivable	$	252,413		$	214,608
Notes receivable		-			16
Other receivables		1,623			2,108
Gross receivables		254,036			216,732
Allowance for doubtful accounts receivable		(767	)		(125	)
Net receivables	$	253,269		$	216,607