CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, less allowance for doubtful accounts	$ 1,525	$ 1,952
Capital Stock, par value (in dollars per share)	$ 1	$ 1
Capital Stock, authorized shares	50,000,000	50,000,000
Capital Stock, shares outstanding	18,255,000	18,021,000