Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Allowance for doubtful accounts on accounts receivable	$ 5,885	$ 5,519	$ 4,232
Accumulated depreciation and amortization on property, plant and equipment	$ 865,852	$ 853,675	$ 826,781
Common stock, par value	$ 2.25	$ 2.25	$ 2.25
Common stock, shares authorized	40,000,000	40,000,000	40,000,000
Common stock, shares issued	26,781,785	26,781,785	26,781,785
Common stock, shares outstanding	26,781,785	26,781,785	26,781,785