Divestiture and Acquisitions (Divestitures) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Feb. 08, 2019	Sep. 24, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents			$ 7,998.2	$ 6,536.2	$ 4,582.1	$ 3,666.4
Noncontrolling interests			1,080.4	$ 75.7
Elanco Animal Health Incorporated
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of stock sold (in percentage)		19.80%
Cash and cash equivalents			475.0
Noncontrolling interests			$ 1,020.0
IPO | Elanco Animal Health Incorporated
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Initial public offering (in shares)		72,300
Sale of stock, price per share (usd per share)		$ 24
Elanco Animal Health Incorporated | Disposal Group, Disposed of by Means Other than Sale, Not Discontinued Operations, Spinoff
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash transfered from subsidiary to parent		$ 4,200.0
Sale of Elanco Stock (Note 3)		$ 629.2
Subsequent Event | Elanco Animal Health Incorporated | Disposal Group, Disposed of by Means Other than Sale, Not Discontinued Operations, Spinoff
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Shares, Expected to Divest	293,290
Minimum Number of Shares to Divest for Exchange Offer	146,645