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, 2016 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	50,994,139	[1]
Weighted average remaining contractual life, vested and expected to vest (in years)	6 years 6 months	[1]
Weighted average exercise price per share, vested and expected to vest (in dollars per share) | $ / shares	$ 41.63	[1]
Intrinsic value, vested and expected to vest (millions of dollars) | $	$ 1,598	[1]
Outstanding options exercisable (in shares) | shares	24,017,386
Weighted average remaining contractual life, options exercisable	4 years 10 months 24 days
Weighted average exercise price per share, options exercisable (in dollars per share) | $ / shares	$ 33.16
Intrinsic value, options exercisable (millions of dollars) | $	$ 956

[1] Includes effects of expected forfeitures of approximately 1 million shares. Excluding the effects of expected forfeitures, the aggregate intrinsic value of stock options outstanding was $1,624 million.