Segment Information (Reportable Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2015	Oct. 04, 2015	Jul. 05, 2015	Apr. 05, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net revenues	$ 158,236	$ 134,833	$ 146,392	$ 150,798	$ 164,243	$ 159,258	$ 166,906	$ 165,860	$ 590,259	$ 656,267	$ 841,446
Revenues									994	1,124	1,783
Operating income (loss)									10,918	26,174	64,757
Other Operating Income									42,410	62,487	86,210
Restructuring Costs and Asset Impairment Charges									14,321	21,959	8,715
Restructuring related inventory charges									8,975	4,634	5,246
Impairment charges									208	2,502	726
Special charges									8,196	9,720
Interest expense									3,310	2,844	2,652
Other income, net									(2,072)	902	(1,156)
Income before income taxes									9,680	22,428	63,261
Identifiable assets	820,756				669,915				820,756	669,915	724,722
Capital expenditures									14,692	12,711	12,810
Depreciation and amortization									25,619	23,935	19,562
Energy [Member]
Segment Reporting Information [Line Items]
Net revenues									322,046	383,655	552,973
Operating income (loss)									34,619	50,386	79,742
Restructuring related inventory charges									3,185	2,903	1,963
Special charges									2,920	8,648
Identifiable assets	658,749				463,359				658,749	463,359	545,216
Capital expenditures									3,902	6,176	6,157
Depreciation and amortization									8,755	7,102	8,503
Aerospace [Member]
Segment Reporting Information [Line Items]
Net revenues									268,213	272,612	288,473
Operating income (loss)									33,463	33,811	29,883
Identifiable assets	407,035				486,369				407,035	486,369	291,821
Capital expenditures									8,535	6,324	5,412
Depreciation and amortization									15,555	15,624	9,949
Corporate/Eliminations [Member]
Segment Reporting Information [Line Items]
Net revenues									(994)	(1,124)	(1,783)
Operating income (loss)									(25,672)	(21,710)	(23,415)
Identifiable assets	(245,028)				(279,813)				(245,028)	(279,813)	(112,315)
Capital expenditures									1,775	814	1,241
Depreciation and amortization									1,309	1,209	1,110
Corporate Identifiable Assets After Elimination Of Intercompany Assets [Member]
Segment Reporting Information [Line Items]
Identifiable assets	$ 50,500				$ 46,700				50,500	46,700	48,800
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Restructuring related inventory charges									2,846	9,391	7,989
Impairment charges									208	2,502	726
Special restructuring charges, net									8,975	4,634	5,246
Acquisition amortization									9,901	6,838	0
Special other charges, net									8,196	9,720	7,491
Special charges									17,171	14,354	12,737
Brazil restatement impact									0	3,228	0
Restatement Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Capital expenditures									$ 14,212	$ 13,314	$ 12,810