Stock Based Awards and Other Equity Instruments - Summary of Stock Option (Details) - Stock Options $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Options Outstanding
Options Outstanding, Beginning balance | shares	5,720
Options Outstanding, Granted | shares	1,064
Options Outstanding, Exercised | shares	(733)	[1]
Options Outstanding, Cancelled or expired | shares	(233)
Options Outstanding, Ending balance | shares	5,818
Options Outstanding, Exercisable | shares	2,796
Weighted Average Exercise Price per share
Options Outstanding, Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 53.71
Options Granted, Weighted Average Exercise Price | $ / shares	63.43
Options Exercised, Weighted Average Exercise Price | $ / shares	31.58	[1]
Options Cancelled or expired, Weighted Average Exercise Price | $ / shares	70.76
Options Outstanding, Weighted Average Exercise Price, Ending balance | $ / shares	57.60
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 42.95
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 6 months
Options Exercisable, Weighted Average Remaining Contractual Life	4 years 3 months 18 days
Options Outstanding, Aggregate Intrinsic Value | $	$ 25
Options Exercisable, Aggregate Intrinsic Value | $	$ 24

[1] Inclusive of 318,773 options, which were not converted into shares due to net share settlement in order to cover the aggregate exercise price and the minimum amount of required employee withholding taxes. Potential shares which had been convertible under stock options that were withheld under net share settlement remain in the authorized but unissued pool under the 2011 Incentive Plan and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the consolidated statements of cash flows.