Goodwill and Other Intangible Assets - Schedule of Goodwill and Fair Value by Reporting Unit (Details) - USD ($) $ in Millions	Dec. 31, 2017	Oct. 01, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 27, 2015
Goodwill [Line Items]
Goodwill	$ 4,175.4		$ 4,049.4	$ 5,152.7	$ 4,721.2
CHCI
Goodwill [Line Items]
Goodwill	1,205.7		1,070.8	1,983.2	1,530.2
CHCI | BCH
Goodwill [Line Items]
Goodwill	1,026.0
Reporting unit, percentage of fair value in excess of carrying amount (less than)		6.60%
CHCI | UK AUS
Goodwill [Line Items]
Goodwill	53.1
Reporting unit, percentage of fair value in excess of carrying amount (less than)		18.30%
CHCA
Goodwill [Line Items]
Goodwill	1,847.4		$ 1,810.6	$ 1,814.3	$ 1,817.2
CHCA | Animal health
Goodwill [Line Items]
Goodwill	$ 178.9
Reporting unit, percentage of fair value in excess of carrying amount (less than)		23.60%