v2.4.0.8
Stock-based compensation (Narrative) (Details) (USD $)
9 Months Ended
Sep. 28, 2013
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross 1,054,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value $ 4.44
Share-based Compensation Arrangement by Share-based Payment Award, Method of Measuring Cost of Award Black-Scholes
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights ratably
Share Based Compensation Arrangement By Share Based Payment Award Expiration Period tenth
Minimum [Member]
 
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 1 year
Maximum [Member]
 
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 5 years