CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current Assets:
Trade accounts receivable, allowance for losses	$ 5,976	$ 6,000
Intangible assets, accumulated amortization	$ 20,325	$ 17,432
Shareholders' Equity:
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	53,954,874	53,954,874
Treasury stock, shares (in shares)	11,731,223	10,759,291