Summary of Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 29, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 29, 2018	Dec. 30, 2017
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 1,008	$ 1,018	$ 1,009	$ 941	$ 903	$ 923	$ 1,005	$ 947	$ 3,976		$ 3,778	$ 3,580
Gross profit	188	191	193	177	159	166	183	176	749		684	652
Goodwill impairment	(1)	939	0	0					938		0	0
Operating (loss) income	(25)	(958)	(5)	(9)	33	34	38	32	(997)		137	135
Net (loss) income attributable to Covetrus	$ (37)	$ (959)	$ (10)	$ (13)	$ 33	$ 16	$ 29	$ 23	$ (1,019)	[1]	$ 101	$ 64
Earnings (loss) per share:
Basic (in usd per share)	$ (0.33)	$ (8.56)	$ (0.09)	$ (0.14)	$ 0.47	$ 0.22	$ 0.40	$ 0.32	$ (9.50)		$ 1.41	$ 0.90
Diluted (in usd per share)	$ (0.33)	$ (8.56)	$ (0.09)	$ (0.14)	$ 0.46	$ 0.22	$ 0.40	$ 0.31	$ (9.50)		$ 1.40	$ 0.89

[1] Net income earned from January 1, 2019 through February 7, 2019 is attributed to the former parent as it was the sole shareholder prior to February 7, 2019