Employee Stock-Based Incentives - RSUs, Employee Stock Options and SARS Activities (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock Units (RSUs)
RSU Number of Shares:
Outstanding, January 1	121,241
Granted	37,817
Vested	(54,265)
Forfeited	(4,225)
Outstanding, December 31	100,568	121,241
RSU's Weighted-Average Grant Date Fair Value (in dollars per share):
Outstanding, January 1	$ 41.47
Granted	$ 57.88
Vested	$ 40.67
Forfeited	$ 47.32
Outstanding, December 31	$ 47.81	$ 41.47
Employee Stock Options and SARs Weighted-Average Exercise Price (in dollars per share):
Total fair value of RSUs that vested	$ 3,200,000,000	$ 2,900,000,000	$ 2,800,000,000
Employee Stock Options and SARs [Member]
Employee Stock Options and SARs Number of Shares:
Outstanding, January 1	87,075
Granted	101
Exercised	(24,950)
Forfeited	(2,059)
Canceled	(972)
Outstanding, December 31	59,195	87,075
Exercisable, December 31	37,171
Employee Stock Options and SARs Weighted-Average Exercise Price (in dollars per share):
Outstanding, January 1	$ 44.24
Granted	$ 59.18
Exercised	$ 36.59
Forfeited	$ 41.90
Canceled	$ 200.86
Outstanding, December 31	$ 45.00	$ 44.24
Exercisable, December 31	$ 46.46
Employee stock option and SARs activity, Weighted-average remaining contractual life (in years), Outstanding, December 31	5 years 2 months 12 days
Employee stock option and SARs activity, Weighted-average remaining contractual life (in years), Exercisable, December 31	4 years 3 months 18 days
Employee stock option and SARs activity, Aggregate intrinsic value, Outstanding, December 31	1,313,939,000
Employee stock option and SARs activity, Aggregate intrinsic value, Exercisable, December 31	862,374,000
Weighted average grant date per share of stock options and SARs granted		$ 9.58	$ 8.89
Employee Stock Option
Employee Stock Options and SARs Weighted-Average Exercise Price (in dollars per share):
Total intrinsic value of options exercised	$ 539,000,000	$ 507,000,000	$ 283,000,000