CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Receivables, less allowances of $5,052 and $4,430, respectively	$ 5,052	$ 4,430
Shareholders' equity:
Common shares, authorized (in shares)	65,000,000	65,000,000
Common shares, par value (in dollars per share)	$ 0.10	$ 0.10
Common shares, outstanding (in shares)	46,522,000	46,630,000