Unaudited Condensed Consolidated and Combined Statements of Equity - USD ($) shares in Thousands, $ in Millions		Total	Aratana	Common Stock	Common Stock Aratana		Additional Paid-in Capital	Additional Paid-in Capital Aratana	Net Parent Company Investment	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Foreign Currency Translation	Defined Benefit Pension and Retiree Health Benefit Plans
Balance at beginning of period (in shares) at Dec. 31, 2017				293,300
Balance at beginning of period at Dec. 31, 2017		$ 7,780.3		$ 0.0			$ 0.0		$ 8,036.9	$ 0.0	$ (256.6)	$ (227.2)	$ (29.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		72.7							72.7
Other comprehensive income (loss), net of tax		118.6									118.6	119.2	(0.6)
Transfers (to)/from Lilly, net	[1]	(69.2)							(69.2)
Balance at end of period (in shares) at Mar. 31, 2018				293,300
Balance at end of period at Mar. 31, 2018		7,902.1		$ 0.0			0.0		8,040.1	0.0	(138.0)	(108.0)	(30.0)
Balance at beginning of period (in shares) at Dec. 31, 2017				293,300
Balance at beginning of period at Dec. 31, 2017		7,780.3		$ 0.0			0.0		8,036.9	0.0	(256.6)	(227.2)	(29.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		70.1
Other comprehensive income (loss), net of tax		(9.8)
Transfers (to)/from Lilly, net									(226.3)
Balance at end of period (in shares) at Sep. 30, 2018				365,600
Balance at end of period at Sep. 30, 2018		5,137.1		$ 0.0			5,347.4		0.0	0.0	(210.3)	(191.7)	(18.6)
Balance at beginning of period (in shares) at Mar. 31, 2018				293,300
Balance at beginning of period at Mar. 31, 2018		7,902.1		$ 0.0			0.0		8,040.1	0.0	(138.0)	(108.0)	(30.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		(62.8)							(62.8)
Other comprehensive income (loss), net of tax		(222.9)									(222.9)	(224.9)	2.0
Transfers (to)/from Lilly, net	[1]	(40.3)							(40.3)
Balance at end of period (in shares) at Jun. 30, 2018				293,300
Balance at end of period at Jun. 30, 2018		7,576.1		$ 0.0			0.0		7,937.0	0.0	(360.9)	(332.9)	(28.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		60.2							60.2
Other comprehensive income (loss), net of tax		94.5									94.5	85.1	9.4
Transfers (to)/from Lilly, net	[1]	(116.8)							(116.8)
Separation activities	[1]	58.3							2.2		56.1	56.1
Issuance of common stock (in shares)				72,300
Issuance of common stock		1,659.7					1,659.7
Consideration to Lilly in connection with the Separation		(4,194.9)					(4,194.9)
Reclassification of net parent company investment		0.0					7,882.6		(7,882.6)
Balance at end of period (in shares) at Sep. 30, 2018				365,600
Balance at end of period at Sep. 30, 2018		5,137.1		$ 0.0			5,347.4		0.0	0.0	(210.3)	(191.7)	(18.6)
Balance at beginning of period (in shares) at Dec. 31, 2018				365,600
Balance at beginning of period at Dec. 31, 2018		5,197.5		$ 0.0			5,403.3		0.0	16.4	(222.2)	(218.2)	(4.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		31.5								31.5
Other comprehensive income (loss), net of tax		(28.2)									(28.2)	(30.2)	2.0
Separation activities	[2]	(7.0)					(7.0)
Stock compensation		2.4					2.4
Issuance of stock under employee stock plans, net in connection with Aratana acquisition (in shares)				100
Balance at end of period (in shares) at Mar. 31, 2019				365,700
Balance at end of period at Mar. 31, 2019		5,196.2		$ 0.0			5,398.7		0.0	47.9	(250.4)	(248.4)	(2.0)
Balance at beginning of period (in shares) at Dec. 31, 2018				365,600
Balance at beginning of period at Dec. 31, 2018		5,197.5		$ 0.0			5,403.3		0.0	16.4	(222.2)	(218.2)	(4.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		77.4
Other comprehensive income (loss), net of tax		(30.3)
Separation activities							28.4
Balance at end of period (in shares) at Sep. 30, 2019				373,000
Balance at end of period at Sep. 30, 2019		5,487.7		$ 0.0			5,646.4		0.0	93.8	(252.5)	(271.9)	19.4
Balance at beginning of period (in shares) at Mar. 31, 2019				365,700
Balance at beginning of period at Mar. 31, 2019		5,196.2		$ 0.0			5,398.7		0.0	47.9	(250.4)	(248.4)	(2.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		35.9								35.9
Other comprehensive income (loss), net of tax		35.6									35.6	35.4	0.2
Separation activities	[2]	(18.4)					(18.4)
Stock compensation		14.3					14.3
Other		1.9					1.9
Balance at end of period (in shares) at Jun. 30, 2019				365,700
Balance at end of period at Jun. 30, 2019		5,265.5		$ 0.0			5,396.5		0.0	83.8	(214.8)	(213.0)	(1.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		10.0								10.0
Other comprehensive income (loss), net of tax		(37.7)									(37.7)	(58.9)	21.2
Separation activities	[2]	(3.0)					(3.0)
Stock compensation		11.3					11.3
Issuance to Aratana shareholders for acquisition (in shares)	[3]				7,200
Issuance to Aratana shareholders for acquisition	[3]		$ 238.0					$ 238.0
Accelerated vesting of equity awards (in shares)			100		100	[3]
Accelerated vesting of equity awards	[3]		$ 3.6					$ 3.6
Balance at end of period (in shares) at Sep. 30, 2019				373,000
Balance at end of period at Sep. 30, 2019		$ 5,487.7		$ 0.0			$ 5,646.4		$ 0.0	$ 93.8	$ (252.5)	$ (271.9)	$ 19.4

[1] See Note 17: Related Party Agreements and Transactions for further discussion.

[2] See Note 17: Related Party Agreements and Transactions for further discussion.

[3] See Note 6: Acquisitions for further discussion.