Share-Based Incentive Compensation (details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Share-Based Incentive Compensation disclosure
Stock options vested at end of period, number (in shares)	7,684,929		7,684,929
Stock options vested at end of period, weighted average exercise price (per share)	$ 67.85		$ 67.85
Stock options vested at end of period, weighted average contractual life remaining			6 years 1 month 6 days
Stock options vested at end of period, aggregate intrinsic value	$ 251		$ 251
Stock options exercisable at end of period, number (in shares)	4,625,049		4,625,049
Stock options exercisable at end of period, weighted average exercise price (per share)	$ 53.53		$ 53.53
Stock options exercisable at end of period, weighted average contractual life remaining			4 years 7 months 6 days
Stock options exercisable at end of period, aggregate intrinsic value	$ 213		$ 213
Total compensation cost recognized in earnings for all share-based incentive compensation awards	31	$ 31	109	$ 106
Tax benefit recognized in earnings related to compensation costs	11	$ 10	37	$ 36
Total unrecognized compensation cost related to all nonvested share-based incentive compensation awards	$ 152		$ 152		$ 123
Weighted-average period of recognition for unrecognized compensation cost			1 year 9 months 18 days		1 year 8 months 12 days