Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 58	$ 87	$ 166	$ 175
Options, grants in period (in shares)			4,000,000
Options, grants in period, weighted average grant date fair value (in dollars per share)			$ 13.02
Options, grants in period, weighted average exercise price (in dollars per share)			$ 104.75
Options, outstanding (in shares)	24,000,000		24,000,000
Options, outstanding, weighted average exercise price (in dollars per share)	$ 68.31		$ 68.31
Options, outstanding, weighted average remaining contractual term (in years)			3 years 11 months 9 days
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 20	22	$ 60	67
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 38	$ 65	$ 106	$ 108
Equity instruments other than options, grants in period (in shares)			2,000,000
Equity instruments other than options, grants in period, weighted average grant date fair value (in dollars per share)			$ 103.47
Equity instruments other than options, nonvested (in shares)	5,000,000		5,000,000
Equity instruments other than options, nonvested, weighted average grant date fair value (in dollars per share)	$ 56.20		$ 56.20