XML 65 R43.htm IDEA: XBRL DOCUMENT v3.20.4
Earnings (Loss) Per Share - Summary of Earnings (Loss) Per Share Calculation (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 27, 2020
Sep. 27, 2020
Jun. 28, 2020
Mar. 29, 2020
Dec. 29, 2019
Sep. 29, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 27, 2020
Dec. 29, 2019
Dec. 30, 2018
Earnings Per Share [Abstract]                      
Net loss attributable to Potbelly Corporation $ (16,427) $ (13,412) $ (22,216) $ (13,336) $ (1,332) $ (2,355) $ (1,866) $ (18,439) $ (65,391) $ (23,992) $ (8,878)
Weighted average common shares outstanding-basic                 23,899 23,850 25,173
Weighted average common shares outstanding-diluted                 23,899 23,850 25,173
Loss per share available to common stockholders-basic $ (0.68) $ (0.56) $ (0.93) $ (0.56) $ (0.06) $ (0.10) $ (0.08) $ (0.76) $ (2.74) $ (1.01) $ (0.35)
Loss per share available to common stockholders-diluted $ (0.68) $ (0.56) $ (0.93) $ (0.56) $ (0.06) $ (0.10) $ (0.08) $ (0.76) $ (2.74) $ (1.01) $ (0.35)
Potentially dilutive shares that are considered anti-dilutive                 2,754 2,334 2,499