Stock-Based Compensation- Stock Option Activity (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock option activity
Outstanding, Beginning Balance, Number of Shares Underlying Options	901,000	1,059,000	1,539,000
Granted, Number of Shares Underlying Options	0	0	0
Exercised, Number of Shares Underlying Options	(53,000)	(94,000)	(446,000)
Forfeited, Number of Shares Underlying Options	(161,000)	(64,000)	(34,000)
Outstanding, Ending Balance, Number of Shares Underlying Options	687,000	901,000	1,059,000	1,539,000
Exercisable, Number of Shares Underlying Options	687,000
Outstanding, Beginning Balance, Weighted Average Exercise Price per Share	$ 38.06	$ 36.31	$ 34.58
Granted, Weighted Average Exercise Price per Share	$ 0	$ 0	$ 0
Exercised, Weighted Average Exercise Price per Share	$ 19.68	$ 19.52	$ 29.54
Forfeited, Weighted Average Exercise Price per Share	$ 37.26	$ 36.19	$ 46.73
Outstanding, Ending Balance, Weighted Average Exercise Price per Share	$ 39.68	$ 38.06	$ 36.31	$ 34.58
Exercisable, Weighted Average Exercise Price per Share	$ 39.68
Weighted average fair value of each option	$ 0	$ 0	$ 0
Outstanding, Beginning Balance, Weighted Average Remaining Contractual Life (In years)	1 year 11 months	3 years 4 months 0 days	4 years 0 months 0 days	4 years 8 months 0 days
Outstanding, Ending Balance, Weighted Average Remaining Contractual Life (In years)	1 year 11 months	3 years 4 months 0 days	4 years 0 months 0 days	4 years 8 months 0 days
Exercisable, Weighted Average Remaining Contractual Life (In years)	1 year 11 months
Outstanding, Beginning Balance, Aggregate Intrinsic Value	$ 1	$ 7	$ 58
Exercised, Aggregate Intrinsic Value	1	1	18
Outstanding, Ending Balance, Aggregate Intrinsic Value	0	1	7	58
Exercisable, Aggregate Intrinsic Value	$ 0