Related Party Agreements and Transactions - Narrative (Details) - USD ($) $ in Millions		3 Months Ended												9 Months Ended
		Sep. 30, 2019		Jun. 30, 2019	[1]	Mar. 31, 2019	[1]	Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Separation activities		$ (3.0)	[1]	$ (18.4)		$ (7.0)		$ 58.3	[2]
Restricted cash and payable		11.1						634.9						$ 11.1	$ 634.9	$ 202.7
Transfers (to)/from Lilly, net	[2]							(116.8)		$ (40.3)		$ (69.2)
Lilly
Related Party Transaction [Line Items]
Stock-based compensation								6.9						$ 5.1	20.2
Costs of defined benefit pension plan								1.6							0.3
Lilly | TSA
Related Party Transaction [Line Items]
Mark-up rate														7.00%
Lilly | Manufacturing Support
Related Party Transaction [Line Items]
Revenue from related parties								1.3							3.7
Additional Paid-in Capital
Related Party Transaction [Line Items]
Separation activities		$ (3.0)	[1]	$ (18.4)		$ (7.0)								$ 28.4
Net Parent Company Investment
Related Party Transaction [Line Items]
Separation activities	[2]							2.2
Transfers (to)/from Lilly, net								$ (116.8)	[2]	$ (40.3)	[2]	$ (69.2)	[2]		$ (226.3)

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

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