Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts, accounts receivable	$ 3,314	$ 3,417
Accumulated Depreciation Depletion And Amortization Property Plant And Equipment	$ 402,359	$ 379,088
Preferred shares, par value	$ 0.1	$ 0.1
Preferred shares, shares authorized	5,000	5,000
Preferred shares, issued	0	0
Common stock, par value	$ 0.1	$ 0.1
Common stock, shares authorized	145,000	145,000
Common stock, issued	48,754	50,178
Common stock, outstanding	48,754	50,178