Stock-Based and Employee Savings Plans - Stock Option Activity (Details) - Employee Stock Option shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares
Stock Option Activity
Stock options outstanding, beginning of period (in shares)	10
Granted and assumed (in shares)	2
Exercised (in shares)	(6)
Forfeited/expired/canceled (in shares)	(1)
Adjustment due to the Distribution (in shares)	2
Stock options outstanding, end of period (in shares)	7	10
Expected to vest (in shares)	6
Options exercisable (in shares)	4
Weighted Average Exercise Price
Weighted average exercise price, outstanding at beginning of period (in usd per share) | $ / shares	$ 34.14
Weighted average exercise price, granted and assumed (in usd per share) | $ / shares	49.59
Weighted average exercise price, exercised (in usd per share) | $ / shares	$ 18.46
Weighted average exercise price, forfeited/expired/canceled (in usd per share) | $ / shares	29.44
Weighted average exercise price, outstanding at end of period (in usd per share) | $ / shares	20.05	$ 34.14
Weighted average exercise price, expected to vest (in usd per share) | $ / shares	19.88
Weighted average exercise price, options exercisable (in usd per share) | $ / shares	$ 17.44
Weighted average remaining contractual term, outstanding	4 years 3 months 22 days
Weighted average remaining contractual term, expected to vest	4 years 2 months 20 days
Weighted average remaining contractual term, options exercisable	2 years 11 months 23 days
Aggregate intrinsic value, options outstanding | $	$ 50
Aggregate intrinsic value, expected to vest | $	48
Aggregate intrinsic value, options exercisable | $	$ 37
Additional Disclosures
Options to purchase common shares in the money (in shares)	7
Weighted average grant date fair value of options granted, during period (in usd per share) | $ / shares	$ 6.84	$ 13.59	$ 15.39
Aggregate intrinsic value of options exercised determined as of the date of option exercise | $	$ 130	$ 159	$ 292