Segment Information (Reportable Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2017	Oct. 02, 2016	Oct. 01, 2017	Oct. 02, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Restructuring Costs and Asset Impairment Charges	$ 2,694	$ 2,096	$ 7,843	$ 7,907
Net revenues	159,693	134,833	456,131	432,023
Operating Income (Loss)	6,864	3,513	25,622	14,355
Other Operating Income	11,877	8,241	33,021	31,426
Other Nonrecurring (Income) Expense	1,978	379	(5,809)	2,491
Restructuring Charges	341	2,252	5,366	6,674
Asset Impairment Charges	0	208	0	208
Interest expense	2,445	605	6,298	1,841
Other income, net	823	163	2,022	(914)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	3,596	2,745	17,302	13,428
Identifiable assets	879,031		879,031		$ 820,756
Capital expenditures			7,773	10,776
Corporate Identifiable Assets After Elimination Of Intercompany Assets [Member]
Segment Reporting Information [Line Items]
Identifiable assets	51,500	51,300	51,500	51,300
Energy [Member]
Segment Reporting Information [Line Items]
Net revenues	92,613	68,901	255,334	233,046
Operating Income (Loss)	7,397	6,755	23,118	25,343
Other Nonrecurring (Income) Expense	192	379	(11,581)	2,489
Restructuring Charges	138	1,093	3,107	1,340
Identifiable assets	690,572		690,572		658,749
Aerospace [Member]
Segment Reporting Information [Line Items]
Net revenues	67,080	65,932	200,797	198,977
Operating Income (Loss)	9,548	8,008	25,845	24,524
Identifiable assets	421,128		421,128		407,035
Corporate/Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	(5,067)	(6,522)	(15,942)	(18,441)
Identifiable assets	(232,669)		(232,669)		$ (245,028)
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Special Restructuring Charges	341	2,252	5,366	6,674
Special Other Charges	1,978	379	(5,809)	2,491
Other Nonrecurring (Income) Expense	2,319	2,631	(443)	9,165
Restructuring Charges	0	0	0	2,032
Asset Impairment Charges				208
Special Acquisition Amortization	$ 2,694	$ 1,888	$ 7,843	$ 5,667