Summary of Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019		Dec. 29, 2018
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 1,121	$ 1,126	$ 1,026	$ 1,065	$ 1,008	$ 1,018	$ 1,009	$ 941	$ 4,339	$ 3,976		$ 3,778
Gross profit	206	197	192	202	188	191	193	177	798	749		684
Goodwill impairment	0	0	0	0	(1)	939	0	0	0	938		0
Operating (loss) income	(19)	(27)	(4)	(20)	(25)	(958)	(5)	(9)	(69)	(997)		137
Net income (loss) attributable to Covetrus	$ (4)	$ (35)	$ 54	$ (33)	$ (37)	$ (920)	$ (10)	$ (13)	$ (19)	$ (980)	[1]	$ 101
Earnings (loss) per share:
Basic (in usd per share)	$ (0.04)	$ (0.33)	$ 0.40	$ (0.30)	$ (0.33)	$ (8.22)	$ (0.09)	$ (0.14)	$ (0.22)	$ (9.14)		$ 1.41
Diluted (in usd per share)	$ (0.04)	$ (0.33)	$ 0.40	$ (0.30)	$ (0.33)	$ (8.22)	$ (0.09)	$ (0.14)	$ (0.22)	$ (9.14)		$ 1.40

[1] (a) 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