Summary of significant accounting policies (Details) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($) segment	Dec. 31, 2017 USD ($)
Accounting Policies [Abstract]
Number of operating segments \| segment	1
Accumulated depreciation and amortization on property, plant and equipment	$ 8,000	$ 7,600
Change in estimate of sales deductions for prior period sales as a pct of total sales deductions (less than)	1.00%
Sales return provisions as a percentage of gross product sales (less than)	1.00%
New Accounting Pronouncement, Early Adoption [Line Items]
Accumulated deficit	$ (15,987)	(5,072)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Accumulated deficit		$ 25

Sales Deductions On Prior Period Sales Due To Change In Estimate

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Sales Return Provisions As Percentage Of Product Sales

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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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