Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts, accounts receivable	$ 3,417	$ 2,943
Accumulated Depreciation Depletion And Amortization Property Plant And Equipment	$ 379,088	$ 362,620
Preferred shares, par value	$ 0.1	$ 0.1
Preferred shares, shares authorized	5,000	5,000
Preferred shares, issued
Common shares, par value	$ 0.1	$ 0.1
Common shares, shares authorized	145,000	145,000
Common shares, issued	50,178	52,994
Common shares, outstanding	50,178	52,994