XML 43 R32.htm IDEA: XBRL DOCUMENT v3.19.1
Loss Per Share - Summary of Loss Per Share Calculation (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Mar. 31, 2019
Apr. 01, 2018
Loss Per Share [Line Items]    
Net loss attributable to Potbelly Corporation $ (18,439) $ (2,194)
Weighted average common shares outstanding-basic 24,133,038 25,144,855
Weighted average common shares outstanding-diluted 24,133,038 25,144,855
Loss per share available to common stockholders-basic $ (0.76) $ (0.09)
Loss per share available to common stockholders-diluted $ (0.76) $ (0.09)
Common Share Options [Member]    
Loss Per Share [Line Items]    
Potentially dilutive shares that are considered anti-dilutive 2,386,820 3,101,447