Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 187,568	$ 183,284
Trade receivables, net	55,166	75,144
Contract assets	88,990
Other receivables	21,866	20,891
Inventories, net	104,544	138,542
Prepaid expenses and other current assets	4,607	4,217
Total current assets	462,741	422,078
Property, plant and equipment, net	270,378	254,299
Goodwill	44,372	43,626
Intangible assets, net	13,442	13,868
Deferred income taxes	1,822	3,198
Other non-current assets	3,465	3,496
Total assets	796,220	740,565
Current liabilities:
Accounts payable	43,932	35,017
Contract liabilities, current	6,721	4,707
Taxes payable	8,162	43
Accrued expenses and other current liabilities	32,938	42,774
Total current liabilities	91,753	82,541
Contract liabilities, non-current	39,000	39,000
Deferred income taxes	7,129	7,806
Accrued pension benefits	40,633	41,141
Other non-current liabilities	24,968	25,213
Total liabilities	203,483	195,701
Stockholders' equity:
Common stock, $.10 par value; authorized 100,000,000, issued 34,383,644 and 34,270,975 shares at respective dates	3,438	3,427
Additional paid-in capital	170,340	165,979
Retained earnings	470,103	429,826
Treasury stock, at cost, 1,424,153 and 1,424,153 shares at respective dates	(12,140)	(12,140)
Accumulated other comprehensive loss	(39,004)	(42,228)
Total stockholders' equity	592,737	544,864
Total liabilities and stockholders' equity	$ 796,220	$ 740,565