Earnings Per Share - Reconciliation of Basic Shares to Diluted Shares (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 06, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income (loss) attributable to Covetrus		$ (10)	$ 29	$ (23)	$ 51
Basic shares (in shares)		112	71	103	71
Effect of dilutive shares (in shares)	1	0	1	0	1
Diluted shares (in shares)		112	72	103	72
Basic earnings (loss) per share		$ (0.09)	$ 0.40	$ (0.22)	$ 0.72
Diluted earnings (loss) per share		$ (0.09)	$ 0.40	$ (0.22)	$ 0.72