Accounting Policies (Schedule of Accounts Receivable) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Trade and other accounts receivable	$ 123,179	$ 136,479
Bank promissory notes	15,845	17,426
Revenue in excess of progress billings	15,889	13,045
Allowance for doubtful accounts	(8,530)	(8,713)
Total accounts receivable	$ 146,383	$ 158,237