Accounts Receivable and Inventories (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accounts receivable
Trade accounts receivable	$ 636,304,000	$ 605,584,000
Less: Allowance for doubtful accounts	(17,829,000)	(20,283,000)
Trade accounts receivable, net	618,475,000	585,301,000
Other receivables	44,431,000	29,299,000
Provision for doubtful accounts related to trade accounts receivable	7,880,000	9,962,000	9,318,000
Inventories
Finished goods	78,445,000	124,771,000
Work-in-process	34,041,000	28,266,000
Raw materials and purchased parts	92,995,000	79,420,000
Stores and supplies	36,453,000	39,160,000
Total inventories	241,934,000	271,617,000
Valued at lower of cost or market
LIFO basis	115,523,000	117,519,000
FIFO basis	13,087,000	14,148,000
Average cost basis	113,324,000	139,950,000
Total inventories	241,934,000	271,617,000
Excess of inventories valued at current costs over LIFO	28,600,000	26,300,000
Change in income as a result of LIFO basis inventory valuation over FIFO basis valuation	$ 100,000	$ 400,000	$ 1,700,000