Segment Information (Reportable Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2017	Jul. 03, 2016	Jul. 02, 2017	Jul. 03, 2016	Dec. 31, 2016	Apr. 03, 2016
Segment Reporting Information [Line Items]
Restructuring Costs and Asset Impairment Charges	$ 2,599	$ 1,985	$ 5,150	$ 5,811
Net revenues	151,231	146,392	296,439	297,190
Operating income (loss)	11,404	5,347	18,758	10,842
Other Operating Income	12,049	11,926	21,145	23,186
Other Nonrecurring (Income) Expense	(5,520)	1,335	(7,788)	2,111
Restructuring Charges	3,566	3,259	5,025	4,422
Interest expense	2,184	605	3,853	1,236
Other income, net	974	(549)	1,200	(1,077)
INCOME BEFORE INCOME TAXES	8,246	5,291	13,705	10,683
Identifiable assets	849,245	657,475	849,245	657,475	$ 820,756
Capital expenditures			5,504	6,998
Depreciation, Depletion and Amortization	6,670	5,781	13,561	11,573
Corporate Identifiable Assets After Elimination Of Intercompany Assets [Member]
Segment Reporting Information [Line Items]
Identifiable assets	53,800		53,800			$ 48,700
Energy [Member]
Segment Reporting Information [Line Items]
Net revenues	82,586	80,736	162,721	164,145
Operating income (loss)	8,858	9,293	15,722	18,589
Other Nonrecurring (Income) Expense	(9,505)	1,383	(11,773)	2,270
Restructuring Charges	1,947	525	2,969	247
Identifiable assets	675,049	456,153	675,049	456,153
Capital expenditures	706	633	1,496	1,555
Depreciation, Depletion and Amortization	3,113	1,508	6,184	3,034
Aerospace [Member]
Segment Reporting Information [Line Items]
Net revenues	68,645	65,656	133,718	133,045
Operating income (loss)	8,587	8,064	16,297	16,516
Identifiable assets	415,447	432,302	415,447	432,302
Capital expenditures	1,646	2,670	2,604	4,892
Depreciation, Depletion and Amortization	3,211	3,941	6,682	7,882
Corporate/Eliminations [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	(5,396)	(5,431)	(10,874)	(11,919)
Identifiable assets	(241,251)	(230,980)	(241,251)	(230,980)
Capital expenditures	260	123	743	229
Depreciation, Depletion and Amortization	346	332	695	657
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Special Restructuring Charges	3,566	3,259	5,025	4,422
Special Other Charges	(5,520)	1,335	(7,788)	2,111
Other Nonrecurring (Income) Expense	(1,954)	4,594	(2,763)	6,533
Restructuring Charges	0	75	0	2,032
Special Acquisition Amortization	2,599	1,910	5,150	3,779
Restatement Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Capital expenditures	$ 2,612	$ 3,426	$ 4,843	$ 6,676