Business Segment and Geographical Information - Revenues and Assets (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Jan. 02, 2016	Oct. 03, 2015	Jul. 04, 2015	Apr. 04, 2015	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
Revenues by Product Line:
Revenues	$ 100,241	$ 105,519	$ 111,828	$ 96,538	$ 107,600	$ 91,929	$ 98,327	$ 92,251	$ 414,126	$ 390,107	$ 402,127
Income from Continuing Operations Before Provision for Income Taxes:
Total operating income (loss)									45,573	50,119	42,086
Interest expense, net									(1,024)	(748)	(568)
Income from Continuing Operations Before Provision for Income Taxes									44,549	49,371	41,518
Total Assets:
Total Assets	470,691				415,498				470,691	415,498	413,747
Depreciation and Amortization:
Depreciation and amortization									14,326	10,821	11,189
Capital Expenditures:
Capital expenditures									5,804	5,479	6,755
Long-lived assets	47,704				42,293				47,704	42,293	44,965
United States
Revenues by Product Line:
Revenues									165,335	193,383	174,003
Capital Expenditures:
Long-lived assets	18,482				17,373				18,482	17,373	15,685
China
Revenues by Product Line:
Revenues									43,299	50,814	43,867
Capital Expenditures:
Long-lived assets	10,714				12,278				10,714	12,278	13,996
Germany
Capital Expenditures:
Long-lived assets	5,792				63				5,792	63	85
Other
Revenues by Product Line:
Revenues									205,492	145,910	184,257
Capital Expenditures:
Long-lived assets	12,716				12,579				12,716	12,579	15,199
Operating Segments | Papermaking Systems Segment
Revenues by Product Line:
Revenues									366,461	342,661	348,199
Income from Continuing Operations Before Provision for Income Taxes:
Total operating income (loss)									57,427	56,789	50,485
Total Assets:
Total Assets	407,538				354,417				407,538	354,417	343,937
Depreciation and Amortization:
Depreciation and amortization									11,513	7,898	7,724
Capital Expenditures:
Capital expenditures									5,504	4,639	5,640
Operating Segments | Papermaking Systems Segment | Stock-Preparation
Revenues by Product Line:
Revenues									171,378	148,341	127,496
Operating Segments | Papermaking Systems Segment | Doctoring, Cleaning, & Filtration
Revenues by Product Line:
Revenues									105,938	101,523	117,389
Operating Segments | Papermaking Systems Segment | Fluid-Handling
Revenues by Product Line:
Revenues									89,145	92,797	103,314
Operating Segments | Wood Processing Systems
Revenues by Product Line:
Revenues									36,850	36,387	41,647
Income from Continuing Operations Before Provision for Income Taxes:
Total operating income (loss)									8,327	10,926	6,977
Total Assets:
Total Assets	52,407				53,347				52,407	53,347	55,634
Depreciation and Amortization:
Depreciation and amortization									2,188	2,384	2,977
Corporate and Fiber-based Products
Income from Continuing Operations Before Provision for Income Taxes:
Total operating income (loss)									(20,181)	(17,596)	(15,376)
Total Assets:
Total Assets	$ 10,746				$ 7,734				10,746	7,734	14,176
Depreciation and Amortization:
Depreciation and amortization									625	539	488
Capital Expenditures:
Capital expenditures									300	840	1,115
Corporate and Fiber-based Products | Fiber-based Products
Revenues by Product Line:
Revenues									$ 10,815	$ 11,059	$ 12,281