Accounts Receivable and Inventories (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts Receivable, Net, Current [Abstract]
Trade accounts receivable	$ 359,819,000	$ 617,517,000
Less: Allowance for doubtful accounts	(6,638,000)	(17,253,000)
Trade accounts receivable, net	353,181,000	600,264,000
Other receivables	46,470,000	39,836,000
Provision for doubtful accounts related to trae accounts receivable	10,175,000	11,266,000	7,880,000
Inventories
Finished goods	23,112,000	69,904,000
Work-in-process	25,623,000	28,944,000
Raw materials and purchased parts	72,118,000	99,058,000
Stores and supplies	34,836,000	38,606,000
Total inventories	155,689,000	236,512,000
Valued at lower of cost or market:
LIFO basis	94,939,000	108,633,000
FIFO basis	9,859,000	14,641,000
Average cost basis	50,891,000	113,238,000
Total inventories	155,689,000	236,512,000
Excess of inventories valued at current costs over LIFO	28,400,000	28,500,000
Change in income as a result of LIFO basis inventory valuation over FIFO basis valuation		$ 100,000	$ 100,000