Accounts Receivable and Inventories (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Accounts receivable
Trade accounts receivable		$ 344,470		$ 344,470		$ 340,223
Less: Allowance for doubtful accounts		(15,003)		(15,003)		(15,119)
Trade accounts receivable, net		329,467		329,467		325,104
Other receivables	[1]	22,167		22,167		28,145
Provision for doubtful accounts related to trade accounts receivable		414	$ 7,364	610	$ 7,345
Inventories
Finished goods		36,181		36,181		30,525
Work-in-process		59,047		59,047		28,690
Raw materials and purchased parts		80,671		80,671		87,985
Stores and supplies		32,144		32,144		31,722
Inventories		$ 208,043		$ 208,043		$ 178,922

[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.