Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts, accounts receivable	$ 12,192	$ 10,085
Accumulated Depreciation Depletion And Amortization Property Plant And Equipment	$ 480,970	$ 460,708
Preferred shares, par value	$ 0.10	$ 0.1
Preferred shares, shares authorized	5,000	5,000
Preferred shares, issued
Common stock, par value	$ 0.10	$ 0.1
Common stock, shares authorized	145,000	145,000
Common stock, issued	36,461	36,957
Common stock, outstanding	36,461	36,957