Stock-Based Compensation (Details 3) - Stock Options - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Stock Options
Vesting period	5 years
Expiration period	10 years
Shares
Outstanding at the beginning of the period (in shares)	18,000,000	24,000,000
Granted (in shares)	452,380
Exercised (in shares)	3,000,000	2,000,000
Forfeited (in shares)	3,150,790	3,000,000
Modification upon spin off	2,000,000
Outstanding at the end of the period (in shares)	14,000,000	19,000,000
Option shares vested and expected to vest at the end of the period	14,000,000	19,000,000
Option shares exercisable at the end of the period	12,000,000	16,000,000
Weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 21	$ 22
Granted (in dollars per share)	26	22
Exercised (in dollars per share)	17	16
Forfeited (in dollars per share)	29	28
Forfeitures upon spin off (in dollars per share)	19
Outstanding at the end of the period (in dollars per share)	17	21
Option shares vested and expected to vest at the end of the period (in dollars per share)	17	21
Option shares exercisable at the end of the period (in dollars per share)	$ 18	$ 22
Aggregate intrinsic value
Exercised	$ 32	$ 17
Option shares vested and expected to vest at the end of the period	111	102
Option shares exercisable at the end of the period	$ 96	$ 80
Weighted average remaining option term
Outstanding at the end of the period	4 years	4 years
Option shares vested and expected to vest at the end of the period	4 years	4 years
Option shares exercisable at the end of the period	3 years	3 years
Additional disclosures
Total unrecognized compensation expense	$ 6	$ 7
Weighted average remaining vesting period	2 years	2 years