Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2012

Accounts Receivable [Abstract]

Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]

ACCOUNTS RECEIVABLE

December 31,	2012			2011
(Thousands of dollars)
Trade receivables	$	91,747		$	114,811
Other receivables	7,293			5,423
	99,040			120,234
Allowance for doubtful accounts	(573		)	(339		)
Accounts receivable, net	$	98,467		$	119,895