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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Entity Registrant Name dei_EntityRegistrantName THOMPSON IM FUNDS INC
Entity Central Index Key dei_EntityCentralIndexKey 0000795264
Document Creation Date dei_DocumentCreationDate Jan. 24, 2019
Document Effective Date dei_DocumentEffectiveDate Jan. 24, 2019
Prospectus Date rr_ProspectusDate Mar. 31, 2018