Share-Based Payments (Stock option activity) (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Outstanding, Beginning Balance (in shares)		4,157,129
Granted (in shares)		446,158
Exercised (in shares)		(1,115,451)
Forfeited (in shares)		(24,212)
Outstanding, Ending Balance (in shares)		3,463,624	4,157,129
Weighted-average Exercise Price Per Share
Outstanding, Beginning Balance (in dollars per share)		$ 43.41
Granted (in dollars per share)		87.87
Exercised (in dollars per share)		35.32
Forfeited (in dollars per share)		58.17
Outstanding, Ending Balance (in dollars per share)		$ 51.64	$ 43.41
Outstanding, Weighted-average Remaining Contractual Term (in years)		6 years 2 months 12 days
Outstanding, Aggregate Intrinsic Value	[1]	$ 280
Exercisable, December 31, 2019		1,846,236
Exercisable, Weighted Average Exercise Price Per Share		$ 35.54
Exercisable, Weighted Average Remaining Contractual Term (in years)		4 years 7 months 6 days
Vested and expected to vest, Aggregate Intrinsic Value	[1]	$ 179
Weighted-average grant date fair value per stock option		$ 21.84	$ 20.30	$ 14.31
Aggregate intrinsic value on exercise		$ 76	$ 66	$ 32
Cash received upon exercise		39	36	35
Share-based Payment Arrangement, Exercise of Option, Tax Benefit		$ 31	$ 23	$ 16

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