Stock Options and Other Stock Based Compensation (Details 2)-K - Stock Options - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of Shares
Options outstanding, Beginning balance (in shares)	2,421
Granted (in shares)	688
Exercised (in shares)	(56)
Forfeited or expired (in shares)	(432)
Options outstanding, ending balance (in shares)	2,621	2,421
Options vested or expected to vest (in shares)	2,566
Options exercisable (in shares)	1,563
Weighted Average Exercise Price (per share)
Options outstanding, Beginning balance (in dollars per share)	$ 26.83
Granted (in dollars per share)	23.61
Exercised (in dollars per share)	13.04
Forfeited or expired (in dollars per share)	42.84
Options outstanding, Closing balance (in dollars per share)	23.64	$ 26.83
Options vested or expected to vest (in dollars per share)	23.60
Options exercisable (in dollars per share)	$ 22.16
Weighted Average Remaining Contractual Term (in years)
Options outstanding, Closing balance	3 years 3 months 18 days
Options vested or expected to vest	3 years 2 months 12 days
Options exercisable	1 year 9 months 18 days
Aggregate Intrinsic Value
Options outstanding, Closing balance (in dollars)	$ 4
Options vested or expected to vest (in dollars)	4
Options exercisable (in dollars)	$ 4
Weighted average grant-date fair value of options granted (in dollars per share)	$ 7.79	$ 13.17	$ 12.39
Aggregate intrinsic value of options exercised (in dollars)		$ 3	$ 16
Aggregate cash received from options exercised (in dollars)	$ 1	$ 5	$ 24
Weighted average assumptions used to estimate the fair value of each option grant
Expected life of options (years)	5 years	5 years	5 years
Expected stock price volatility (as a percent)	34.50%	43.00%	55.30%
Risk-free interest rate (as a percent)	1.70%	1.60%	0.90%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%