Asset Impairment, Restructuring, and Other Special Charges (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Asset impairment (gain) and other special charges	$ (20.0)	$ 497.8	$ 139.1
Loxo Oncology, Inc.
Restructuring Cost and Reserve [Line Items]
Asset impairment (gain) and other special charges		$ 400.7