Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Trade and other accounts receivable	$ 132,215	$ 123,179
Bank promissory notes	14,560	15,845
Revenue in excess of progress billings	12,569	15,889
Allowance for doubtful accounts	(8,523)	(8,530)
Total accounts receivable	$ 150,821	$ 146,383