Stock-Based Compensation- Stock Option Activity (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2014	Dec. 31, 2013
Stock option activity
Outstanding, Beginning Balance, Number of Shares Underlying Options	687
Granted, Number of Shares Underlying Options	0
Exercised, Number of Shares Underlying Options	(134)
Forfeited, Number of Shares Underlying Options	(236)
Outstanding, Ending Balance, Number of Shares Underlying Options	317	687
Exercisable, Number of Shares Underlying Options	317
Outstanding, Beginning Balance, Weighted Average Exercise Price per Share	$ 39.68
Granted, Weighted Average Exercise Price per Share	$ 0
Exercised, Weighted Average Exercise Price per Share	$ 29.32
Forfeited, Weighted Average Exercise Price per Share	$ 40.22
Outstanding, Ending Balance, Weighted Average Exercise Price per Share	$ 43.64	$ 39.68
Exercisable, Weighted Average Exercise Price per Share	$ 43.64
Weighted average fair value of each option	$ 0
Outstanding, Beginning Balance, Weighted Average Remaining Contractual Life (In years)	2 years 4 months	1 year 11 months
Outstanding, Ending Balance, Weighted Average Remaining Contractual Life (In years)	2 years 4 months	1 year 11 months
Exercisable, Weighted Average Remaining Contractual Life (In years)	2 years 4 months
Outstanding, Beginning Balance, Aggregate Intrinsic Value	$ 0
Exercised, Aggregate Intrinsic Value	1
Outstanding, Ending Balance, Aggregate Intrinsic Value	0	0
Exercisable, Aggregate Intrinsic Value	$ 0

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Weighted average price of options that were either forfeited or expired.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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