Accounts Receivable and Inventories (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Accounts receivable
Trade accounts receivable	$ 358,191		$ 358,191		$ 617,517
Less: Allowance for doubtful accounts	(4,070)		(4,070)		(17,253)
Trade accounts receivable, net	354,121		354,121		600,264
Other receivables	29,627		29,627		39,836
Provision for doubtful accounts related to trade accounts receivable	1,059	1,802	5,897	8,665
Inventories
Finished goods	21,707		21,707		69,904
Work-in-process	35,214		35,214		28,944
Raw materials and purchased parts	83,037		83,037		99,058
Stores and supplies	36,834		36,834		38,606
Inventories	$ 176,792		$ 176,792		$ 236,512