Asset Impairment, Restructuring, and Other Special Charges (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unusual or Infrequent Item [Line Items]
Severance									$ 142.6	$ 697.4	$ 126.7
Asset impairment (gains from facility sales) and other special charges:									339.4	462.5	255.8
Asset impairment, restructuring, and other special charges	$ 246.0	$ 83.3	$ 74.4	$ 78.3	$ 1,003.2	$ 406.5	$ 50.0	$ 213.9	482.0	1,673.6	382.5
Human pharmaceutical products
Unusual or Infrequent Item [Line Items]
Severance									127.8	601.0	85.9
Asset impairment (gains from facility sales) and other special charges:									46.0	81.7	(13.0)
Animal health products
Unusual or Infrequent Item [Line Items]
Severance									14.8	96.4	40.8
Asset impairment (gains from facility sales) and other special charges:									293.4	380.8	268.8
United States
Unusual or Infrequent Item [Line Items]
Total pension and post-retirement medical charges associated with U.S. voluntary early retirement program									0.0	513.7	0.0
United States | Human pharmaceutical products
Unusual or Infrequent Item [Line Items]
Total pension and post-retirement medical charges associated with U.S. voluntary early retirement program									0.0	446.7	0.0
United States | Animal health products
Unusual or Infrequent Item [Line Items]
Total pension and post-retirement medical charges associated with U.S. voluntary early retirement program									$ 0.0	$ 67.0	$ 0.0