Accounts Receivable and Inventories (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Accounts receivable
Trade accounts receivable	$ 398,471			$ 398,471			$ 359,819
Less: Allowance for doubtful accounts	(13,837)			(13,837)			(6,638)
Trade accounts receivable, net	384,634			384,634			353,181
Other receivables	33,604	[1]		33,604	[1]		46,470	[1]
Provision for doubtful accounts related to trade accounts receivable	7,364		2,621	7,345		4,838
Inventories
Finished goods	25,130			25,130			23,112
Work-in-process	33,022			33,022			25,623
Raw materials and purchased parts	85,731			85,731			72,118
Stores and supplies	32,465			32,465			34,836
Inventories	$ 176,348			$ 176,348			$ 155,689

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