Nature of Operations and Summary of Significant Accounting Policies - Revenue Recognition by Product Line, Product Type, Geography and Revenue Recognition Method (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 159,127	$ 171,316
Parts and Consumables
Disaggregation of Revenue [Line Items]
Revenues	105,098	112,850
Capital
Disaggregation of Revenue [Line Items]
Revenues	54,029	58,466
Point in Time
Disaggregation of Revenue [Line Items]
Revenues	136,092	148,276
Over Time
Disaggregation of Revenue [Line Items]
Revenues	23,035	23,040
North America
Disaggregation of Revenue [Line Items]
Revenues	93,823	100,876
Europe
Disaggregation of Revenue [Line Items]
Revenues	36,014	38,985
Asia
Disaggregation of Revenue [Line Items]
Revenues	15,908	17,078
Rest of World
Disaggregation of Revenue [Line Items]
Revenues	$ 13,382	$ 14,377