Accounts Receivable and Inventories (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Accounts receivable
Trade accounts receivable	$ 717,891,000		$ 717,891,000		$ 605,584,000
Less: Allowance for doubtful accounts	(18,636,000)		(18,636,000)		(20,283,000)
Trade accounts receivable, net	699,255,000		699,255,000		585,301,000
Other receivables	29,652,000		29,652,000		29,299,000
Provision for doubtful accounts related to trade accounts receivable	1,600,000	2,400,000	3,700,000	4,700,000
Inventories
Finished goods	126,314,000		126,314,000		124,771,000
Work-in-process	32,921,000		32,921,000		28,266,000
Raw materials and purchased parts	94,859,000		94,859,000		79,420,000
Stores and supplies	41,426,000		41,426,000		39,160,000
Inventories	$ 295,520,000		$ 295,520,000		$ 271,617,000