Share-Based Payments (Stock option activity) (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares
Outstanding, Beginning Balance (in shares)		4,905,884
Granted (in shares)		538,820
Exercised (in shares)		(1,185,867)
Forfeited (in shares)		(101,708)
Outstanding, Ending Balance (in shares)		4,157,129	4,905,884
Weighted-average Exercise Price Per Share
Outstanding, Beginning Balance (in dollars per share)		$ 37.10
Granted (in dollars per share)		73.32
Exercised (in dollars per share)		30.38
Forfeited (in dollars per share)		49.46
Outstanding, Ending Balance (in dollars per share)		$ 43.41	$ 37.10
Outstanding, Weighted-average Remaining Contractual Term (in years)		6 years 6 months
Outstanding, Aggregate Intrinsic Value	[1]	$ 175
Exercisable, December 31, 2018		2,198,213
Exercisable, Weighted Average Exercise Price Per Share		$ 32.90
Exercisable, Weighted Average Remaining Contractual Term (in years)		5 years 1 month
Vested and expected to vest, Aggregate Intrinsic Value	[1]	$ 116
Weighted-average grant date fair value per stock option		$ 20.30	$ 14.31	$ 11.34
Aggregate intrinsic value on exercise		$ 66	$ 32	$ 23
Cash received upon exercise		36	35	36
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options		$ 23	$ 16	$ 15

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