Acquisition - Narrative (Details) $ in Thousands							3 Months Ended		12 Months Ended
	Nov. 18, 2020 USD ($) shares	Jun. 30, 2020 USD ($)	Jun. 15, 2020 USD ($)	Apr. 17, 2020 USD ($)	Feb. 24, 2020 USD ($)	Feb. 27, 2019 USD ($) shares	Dec. 27, 2020 USD ($)	Sep. 27, 2020 USD ($)	Dec. 27, 2020 USD ($)	Dec. 29, 2019 USD ($) shares	Dec. 30, 2018 USD ($)
Business Acquisition [Line Items]
Business acquisition, equity interest issued or issuable, value assigned						$ 27,000
Deferred tax Liabilities, net										$ 9,000
Merger and acquisition related items									$ 1,700	2,300	$ 0
Discount Rate | Income Approach | Level 3
Business Acquisition [Line Items]
Discount rate							0.125		0.125
Royalty Rate | Income Approach | Level 3
Business Acquisition [Line Items]
Discount rate							0.10		0.10
Florida Turbine Technologies, Inc.
Business Acquisition [Line Items]
Business acquisition, percentage of voting Interests acquired						80.10%
FTT Core, LLC
Business Acquisition [Line Items]
Business acquisition, percentage of voting Interests acquired						80.10%
FTT Inc
Business Acquisition [Line Items]
Business acquisition, percentage of voting Interests acquired						80.10%
Purchase price						$ 60,000
Payments to acquire businesses, gross, including amounts to be paid						33,000
Payment paid at close						17,700
Cash paid						20,700
Payments to acquire businesses, amount to be paid						$ 15,300
Payment period						3 years
Business combination, recognized identifiable assets acquired and liabilities assumed, current liabilities						$ 7,500
Deferred tax Liabilities, net						7,000
Business combination, pro forma information, revenue of acquiree since acquisition date, actual										52,500
Business combination, pro forma information, earnings or loss of acquiree since acquisition date, actual										700
Merger and acquisition related items										$ 1,400
FTT Inc | Customer relationships
Business Acquisition [Line Items]
Finite-lived intangible assets acquired						$ 19,700
Acquired finite-lived intangible assets, weighted average useful life						13 years
FTT Inc | In orocess research and development
Business Acquisition [Line Items]
Finite-lived intangible assets acquired						$ 8,500
FTT Inc | Contracts and backlog
Business Acquisition [Line Items]
Finite-lived intangible assets acquired						$ 2,100
Acquired finite-lived intangible assets, weighted average useful life						2 years
FTT Inc | Trade names
Business Acquisition [Line Items]
Finite-lived intangible assets acquired						$ 500
Acquired finite-lived intangible assets, weighted average useful life						2 years
FTT Inc | Common Stock
Business Acquisition [Line Items]
Business acquisition, equity interest issued or issuable, number of shares | shares						1,825,406				1,825,406
Technical Directions, Inc.
Business Acquisition [Line Items]
Cash paid					$ 10,500
Working capital adjustments								$ 300
Optimized Performance Machining, Inc. (OPM)
Business Acquisition [Line Items]
Cash paid				$ 1,800
Working capital adjustments								$ 30
CPI ASC Signal Division, Inc.
Business Acquisition [Line Items]
Cash paid		$ 34,900	$ 35,000
Business combination, recognized identifiable assets acquired and liabilities assumed, current liabilities		9,100
Deferred tax Liabilities, net		$ 1,100
Business combination, pro forma information, revenue of acquiree since acquisition date, actual							$ 21,900
Business combination, pro forma information, earnings or loss of acquiree since acquisition date, actual							$ 1,100
Merger and acquisition related items									$ 1,100
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred			$ 1,400
CPI ASC Signal Division, Inc. | Customer relationships
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		5 years
Intangible assets		$ 2,000
CPI ASC Signal Division, Inc. | Trade names
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		1 year
Intangible assets		$ 100
CPI ASC Signal Division, Inc. | Developed technology and technical know-how
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life		7 years
Intangible assets		$ 2,200
5-D Systems, Inc
Business Acquisition [Line Items]
Purchase price	$ 10,000
Cash paid	$ 5,000
Business acquisition, equity interest issued or issuable, number of shares | shares	250,374
Business acquisition, equity interest issued or issuable, value assigned	$ 5,000