Net revenues (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Oct. 01, 2017
Concentration Risk [Line Items]
Reserve for returns and allowances	$ 4.6	$ 4.4
Reserve for the customer incentive programs, including distributor rebates	$ 17.1	$ 10.2
Sales Revenue, Net \| Hospitals And Healthcare Providers \| Customer Concentration Risk
Concentration Risk [Line Items]
Percentage of total revenue	86.00%
Sales Revenue, Net \| Other Medical Device Manufacturers \| Customer Concentration Risk
Concentration Risk [Line Items]
Percentage of total revenue	10.00%
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
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Reference 2: 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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