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Financial Instruments Financial Instruments (Details Textual 2) - USD ($) shares in Millions, $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Jun. 05, 2018
Strategic Investments
Business Acquisition [Line Items]
Strategic investment portfolio	$ 1,049.7
Ionis Pharmaceuticals
Business Acquisition [Line Items]
Investment in common stock, shares purchased			11.5
Purchase of common stock			$ 625.0
Other current assets | Strategic Investments
Business Acquisition [Line Items]
Strategic investment portfolio	$ 90.1
Other noncurrent assets | Strategic Investments
Business Acquisition [Line Items]
Strategic investment portfolio		$ 676.3

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