Basis of Presentation and Principles of Consolidation - Schedule of Basic And Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Apr. 14, 2021	Jul. 04, 2021	Jun. 28, 2020	Jul. 04, 2021	Jun. 28, 2020	Apr. 04, 2021	Jan. 03, 2021	Mar. 29, 2020	Dec. 29, 2019
Numerator:
Net loss attributable to SkyWater Technology, Inc.		$ (6,979)	$ (5,293)	$ (9,790)	$ (6,665)
Undistributed preferred return to Class B preferred unitholders, basic		(39)		(398)
Undistributed preferred return to Class B preferred unitholders, diluted		(39)		(398)
Net loss attributable to common shareholders, basic		(7,018)		(10,188)
Net loss attributable to common shareholders, diluted		$ (7,018)		$ (10,188)
Denominator:
Weighted average shares outstanding, basic (in shares)		34,707,758		18,884,051
Weighted average shares outstanding, diluted (in shares)		34,707,758		18,884,051
Net loss per share, basic (in USD per share)		$ (0.20)		$ (0.54)
Net loss per share, diluted (in USD per share)		$ (0.20)		$ (0.54)
Common Units
Denominator:
Number of units converted (in shares)	2,105,936
Units outstanding (in shares)		0	0	0	0	2,106,000	2,108,000	0	0
Common Stock
Denominator:
Conversion of units (in shares)	31,055,743
Common Stock | Common Unit Holders
Denominator:
Conversion of units (in shares)	3,060,343
Common Stock | Class B Preferred Unitholders
Denominator:
Conversion of units (in shares)	27,995,400
Class B Units
Denominator:
Weighted average shares outstanding, basic (in shares)			18,000,000		18,000,000
Weighted average shares outstanding, diluted (in shares)			18,000,000		18,000,000
Net loss per share, basic (in USD per share)			$ (0.29)		$ (0.37)
Net loss per share, diluted (in USD per share)			$ (0.29)		$ (0.37)
Number of units converted (in shares)	18,000,000
Units outstanding (in shares)		0	18,000,000	0	18,000,000	18,000,000	18,000,000	18,000,000	18,000,000