Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity and Share-Based Compensation - Summary of Share-based Compensation from Options, Warrants and Stock Awards (Details)

v2.4.1.9
Stockholders' Equity and Share-Based Compensation - Summary of Share-based Compensation from Options, Warrants and Stock Awards (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Jan. 03, 2015
Dec. 28, 2013
Dec. 29, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Share-based compensation expense $ 2,371us-gaap_ShareBasedCompensation $ 1,263us-gaap_ShareBasedCompensation $ 1,673us-gaap_ShareBasedCompensation
Adjustment related to performance stock options     279prts_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceBasedCriteriaNotAchieved
Marketing expense      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Share-based compensation expense 540us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SellingAndMarketingExpenseMember 		285us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SellingAndMarketingExpenseMember 		505us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_SellingAndMarketingExpenseMember
General and administrative expense      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Share-based compensation expense 1,476us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_GeneralAndAdministrativeExpenseMember 		805us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_GeneralAndAdministrativeExpenseMember 		1,119us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_GeneralAndAdministrativeExpenseMember
Fulfillment expense      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Share-based compensation expense 220us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= prts_FulfillmentMember 		102us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= prts_FulfillmentMember 		(38)us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= prts_FulfillmentMember
Technology expense      
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Share-based compensation expense $ 135us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= prts_TechnologyExpenseMember 		$ 71us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= prts_TechnologyExpenseMember 		$ 87us-gaap_ShareBasedCompensation
/ us-gaap_IncomeStatementLocationAxis
= prts_TechnologyExpenseMember