CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for Doubtful Accounts	$ 1,691	$ 1,354
Accumulated Depreciation	$ 341,119	$ 317,414
Capital Stock, par value (in dollars per share)	$ 1	$ 1,000
Capital Stock, authorized shares (in shares)	50,000,000	50,000,000
Capital Stock, shares issued (in shares)	18,577,000	18,577,000
Capital Stock, shares outstanding (in shares)	18,395,000	18,395,000