Fair value measurement Valuation technique and inputs used to determine fair value of assets or liabilities (Details) - Jun. 28, 2015 - USD ($) $ in Millions	Total	Total
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration liability	$ 3.0	$ 3.0
Probability Of Payment
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration, weighted average		57.30%
Probability Of Payment | Minimum
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration		0.00%
Probability Of Payment | Maximum
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration		100.00%
Market Approach Valuation Technique [Member]
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration, weighted average		7.70%
Market Approach Valuation Technique [Member] | Minimum
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration		1.60%
Market Approach Valuation Technique [Member] | Maximum
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration		10.00%