Accounts Receivable and Inventories (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013
Accounts receivable
Trade accounts receivable	$ 406,267			$ 359,819
Less: Allowance for doubtful accounts	(6,566)			(6,638)
Trade accounts receivable, net	399,701			353,181
Other receivables	52,078	[1]		46,470	[1]
Provision for doubtful accounts related to trade accounts receivable	(19)		2,217
Inventories
Finished goods	22,234			23,112
Work-in-process	31,044			25,623
Raw materials and purchased parts	82,627			72,118
Stores and supplies	30,873			34,836
Inventories	$ 166,778			$ 155,689

[1] Other receivables include insurance claim receivables, employee receivables, tax claim receivables and other miscellaneous receivables not included in Trade accounts receivable, net.