Share-Based Payments (Stock option activity) (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Outstanding, Beginning Balance (in shares)		3,463,624
Granted (in shares)		309,974
Exercised (in shares)		(1,201,072)
Forfeited (in shares)		(18,075)
Outstanding, Ending Balance (in shares)		2,554,451	3,463,624
Weighted-average Exercise Price Per Share
Outstanding, Beginning Balance (in dollars per share)		$ 51.64
Granted (in dollars per share)		144.13
Exercised (in dollars per share)		47.80
Forfeited (in dollars per share)		65.81
Outstanding, Ending Balance (in dollars per share)		$ 64.43	$ 51.64
Outstanding, Weighted-average Remaining Contractual Term (in years)		5 years 8 months 12 days
Outstanding, Aggregate Intrinsic Value	[1]	$ 258
Exercisable, December 31, 2020		1,378,614
Exercisable, Weighted Average Exercise Price Per Share		$ 37.05
Exercisable, Weighted Average Remaining Contractual Term (in years)		3 years 8 months 12 days
Vested and expected to vest, Aggregate Intrinsic Value	[1]	$ 177
Weighted-average grant date fair value per stock option		$ 34.22	$ 21.84	$ 20.30
Aggregate intrinsic value on exercise		$ 114	$ 76	$ 66
Cash received upon exercise		57	39	36
Share-based Payment Arrangement, Exercise of Option, Tax Benefit		$ 39	$ 31	$ 23

[1] Market price of underlying Zoetis common stock less exercise price.