Accounts Receivable and Inventories (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Accounts receivable
Trade accounts receivable	$ 276,625		$ 276,625		$ 280,526
Less: Allowance for doubtful accounts	(13,091)		(13,091)		(25,649)
Trade accounts receivable, net	263,534		263,534		254,877
Other receivables	17,595		17,595		30,395
Provision for doubtful accounts related to trade accounts receivable	(93)	$ 10,005	84	$ 10,615
Inventories
Finished goods	30,198		30,198		32,586
Work-in-process	30,273		30,273		30,959
Contracts-in-process	55,675		55,675		55,786
Raw materials and purchased parts	67,287		67,287		70,755
Stores and supplies	25,262		25,262		26,881
Inventories	208,695		208,695		216,967
Inventory for Contracts
Contract costs accumulated to date	90,668		90,668		55,786
Estimated loss provisions for contracts-in-process	(34,993)		(34,993)		0
Contracts-in-process	55,675		55,675		55,786
Loss provision that exceeds accumulated contract costs	5,500		5,500
Customer Advances and Deposits	$ 106,800		$ 106,800		$ 82,700