CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for credit losses	$ 1,223	$ 1,682
Accumulated depreciation	$ 367,850	$ 365,844
Capital Stock, par value (in dollars per share)	$ 1	$ 1
Capital Stock, authorized shares (in shares)	50,000,000	50,000,000
Capital Stock, shares issued (in shares)	18,730,000	18,677,000
Capital Stock, shares outstanding (in shares)	18,730,000	18,677,000