Stock Compensation - Options Vested and Expected to Vest (Details) - Long-term incentive and director compensation plans - Employee Stock Option $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding shares, vested and expected to vest (in shares) | shares	27,596,705	[1]
Weighted average remaining contractual life, vested and expected to vest (in years)	5 years 9 months 18 days	[1]
Weighted average exercise price per share, vested and expected to vest (in dollars per share) | $ / shares	$ 79.13	[1]
Intrinsic value, vested and expected to vest (millions of dollars)	$ 2,346	[1]
Outstanding options exercisable (in shares) | shares	17,221,451
Weighted average remaining contractual life, options exercisable	4 years 4 months 24 days
Weighted average exercise price per share, options exercisable (in dollars per share) | $ / shares	$ 59.33
Intrinsic value, options exercisable (millions of dollars)	$ 1,805
Aggregate intrinsic value of stock options outstanding, excluding the effects of expected forfeitures	$ 2,360

[1] Includes effects of expected forfeitures. Excluding the effects of expected forfeitures, the aggregate intrinsic value of stock options outstanding was $2.36 billion.