Share-Based Compensation - Schedule of Additional Information on Restricted Stock Units (Details) - Restricted stock units (RSUs) [member] - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Additional Information On Restricted Stock Units [Line Items]
Number of shares granted	942	963	912
Weighted average grant date fair value per share, granted	$ 93.48	$ 83.47	$ 79.31
Aggregate intrinsic value of shares vested	$ 97	$ 92	$ 123