v3.26.1
Loss Per Unit (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 27, 2026
Jun. 28, 2025
Jun. 27, 2026
Jun. 28, 2025
Class A Units [Member]        
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]        
Income attributable to USPB available to unitholders (numerator) $ (525) $ (474) $ (1,224) $ (1,533)
Weighted average outstanding units, Basic 735,385 735,385 735,385 735,385
Weighted average outstanding units, Diluted 735,385 735,385 735,385 735,385
Income per unit, Basic $ (0.71) $ (0.64) $ (1.66) $ (2.08)
Per unit, Diluted $ (0.71) $ (0.64) $ (1.66) $ (2.08)
Class B Units [Member]        
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]        
Income attributable to USPB available to unitholders (numerator) $ (4,722) $ (4,268) $ (11,016) $ (13,793)
Weighted average outstanding units, Basic 755,385 755,385 755,385 755,385
Weighted average outstanding units, Diluted 755,385 755,385 755,385 755,385
Income per unit, Basic $ (6.25) $ (5.65) $ (14.58) $ (18.26)
Per unit, Diluted $ (6.25) $ (5.65) $ (14.58) $ (18.26)