Consolidated Statements of Shareholders' Equity Statement - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Employee Benefit Trust	Accumulated Other Comprehensive Loss	Common Stock in Treasury	Noncontrolling Interest
Beginning balance at Dec. 31, 2015		$ 691.3	$ 5,552.1	$ 16,011.8	$ (3,013.2)	$ (4,580.7)	$ (90.0)	$ 19.0
Shares, Beginning Balance at Dec. 31, 2015		1,106,063					796
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income (loss)				2,737.6				16.3
Other comprehensive income (loss), net of tax	$ (693.3)					(693.3)		48.2
Cash dividends declared				(2,167.6)
Retirement of treasury shares, shares		(7,306)					(7,306)
Retirement of treasury shares		$ (4.6)		(535.5)			$ 540.1
Purchase of treasury shares, shares							7,306
Purchase of treasury shares	(540.1)		(60.0)				$ (540.1)
Issuance of stock under employee stock plans, net, shares		2,829					(85)
Issuance of stock under employee stock plans, net		$ 1.8	(106.8)				$ 9.5
Stock-based compensation			255.3
Other	(10.7)
Shares, Ending Balance at Dec. 31, 2016		1,101,586					711
Ending balance at Dec. 31, 2016		$ 688.5	5,640.6	16,046.3	(3,013.2)	(5,274.0)	$ (80.5)	72.8
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income (loss)				(204.1)				30.5
Other comprehensive income (loss), net of tax	199.0					199.0		(24.5)
Cash dividends declared				(2,234.6)
Retirement of treasury shares, shares		(4,390)					(4,390)
Retirement of treasury shares		$ (2.7)		(357.1)			$ 359.8
Purchase of treasury shares, shares							4,390
Purchase of treasury shares	(359.8)		60.0				$ (359.8)
Issuance of stock under employee stock plans, net, shares		3,476					(47)
Issuance of stock under employee stock plans, net		$ 2.1	(164.1)				$ 4.7
Stock-based compensation			281.3
Other	(3.1)
Shares, Ending Balance at Dec. 31, 2017		1,100,672					664
Ending balance at Dec. 31, 2017	11,667.9	$ 687.9	5,817.8	13,894.1	(3,013.2)	(5,718.6)	$ (75.8)	75.7
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net income (loss)				3,232.0				3.7
Other comprehensive income (loss), net of tax	72.6					85.6		(2.0)
Cash dividends declared				(2,372.0)
Retirement of treasury shares, shares		(45,882)					(45,882)
Retirement of treasury shares		$ (28.7)		(4,122.0)			$ 4,150.7
Purchase of treasury shares, shares							45,882
Purchase of treasury shares	(4,150.0)						$ (4,150.7)
Issuance of stock under employee stock plans, net, shares		2,849					(60)
Issuance of stock under employee stock plans, net		$ 1.8	(139.0)				$ 6.4
Stock-based compensation			279.5
Sale of Elanco Stock (Note 3)			629.2			9.0		1,017.2
Other				(3.9)				(14.2)
Shares, Ending Balance at Dec. 31, 2018		1,057,639					604
Ending balance at Dec. 31, 2018	$ 10,909.1	$ 661.0	$ 6,583.6	$ 11,395.9	$ (3,013.2)	(5,729.2)	$ (69.4)	$ 1,080.4
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Reclassification of stranded tax effects and Adoption of new accounting standards (Note 2)						$ (105.2)