Net revenues (Details) - USD ($) $ in Millions	6 Months Ended
Jul. 01, 2018	Jul. 02, 2017
Concentration Risk [Line Items]
Reserve for returns and allowances	$ 4.2	$ 4.5
Reserve for the customer incentive programs, including distributor rebates	$ 13.6	$ 10.7
Sales Revenue, Net \| Hospitals And Healthcare Providers \| Customer Concentration Risk
Concentration Risk [Line Items]
Percentage of total revenue	87.00%
Sales Revenue, Net \| Other Medical Device Manufacturers \| Customer Concentration Risk
Concentration Risk [Line Items]
Percentage of total revenue	9.00%
Sales Revenue, Net \| Home Care Providers \| Customer Concentration Risk
Concentration Risk [Line Items]
Percentage of total revenue	4.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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