Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts Receivable [Abstract]
Trade and other accounts receivable	$ 132,749	$ 136,479
Bank promissory notes	15,858	17,426
Revenue in excess of progress billings	12,134	13,045
Allowance for doubtful accounts	(8,833)	(8,713)
Total accounts receivable	$ 151,908	$ 158,237