Share-Based Payments - Stock Option Activities (Details) - Stock Option Plan $ / shares in Units, shares in Thousands, $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($) $ / shares shares
Stock option activity, shares
Stock options at the beginning of the period (in shares) | shares	11,297
Stock options, granted (in shares) | shares	709
Stock options, exercised (in shares) | shares	(1,412)
Stock options, forfeited (in shares) | shares	(486)
Stock options, expired (in shares) | shares	(17)
Stock options at the end of the period (in shares) | shares	10,091
Stock options, vested and expected to vest (in shares) | shares	9,596
Stock options, exercisable (in shares) | shares	2,898
Weighted-average exercise price per stock option
Stock options, weighted-average strike price at the beginning of the period (in dollars per share) | $ / shares	$ 53.84
Stock options, weighted-average exercise price, granted (in dollars per share) | $ / shares	93.35
Stock options, weighted-average exercise price, exercised (in dollars per share) | $ / shares	46.55
Stock options, weighted-average exercise price, forfeited (in dollars per share) | $ / shares	64.65
Stock options, weighted-average exercise price, expired (in dollars per share) | $ / shares	56.39
Stock options, weighted-average strike price at the end of the period (in dollars per share) | $ / shares	57.11
Stock options, weighted-average exercise price, vested and expected to vest (in dollars per share) | $ / shares	56.17
Stock options, weighted-average exercise price, exercisable (in dollars per share) | $ / shares	$ 41.43
Stock options, weighted-average remaining contractual term	7 years 5 months 1 day
Stock options, weighted-average remaining contractual term, vested and expected to vest	7 years 4 months 2 days
Stock options, weighted-average remaining contractual term, exercisable	5 years 1 month 28 days
Stock options, aggregate intrinsic value | $	$ 387
Stock options, aggregate intrinsic value, vested and expected to vest | $	377
Stock options, aggregate intrinsic value, exercisable | $	157
Share-based compensation, unrecognized compensation | $	$ 56
Share-based compensation, unrecognized compensation weighted-average period of recognition	1 year 3 months 10 days