Stock-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period from date of grant	10 years
Period of service for immediate vesting upon death, disability or retirement	3 years
Unrecognized compensation cost related to unvested stock option and restricted stock grants	$ 13
Weighted average period over which cost is recognized, years	2 years
2004 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum shares	16,800,000
Expiration period from date of grant	7 years
2002 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum shares	300,000
2000 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum shares	1,250,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for stock awards from grant date	3 years
Deferred tax benefit (liability) recorded	3	4	2
Weighted-average grant-date fair value of options granted	$ 10.16	$ 13.39	$ 16.91
Intrinsic value	4	22	44
Stock-based compensation costs - expensed	5	5	5
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for stock awards from grant date	4 years
Deferred tax benefit (liability) recorded	(10)	(15)	(1)
Unrecognized compensation cost related to the Company's unvested stock option grants, restricted stock grants, and performance units	75
Weighted-average grant-date fair value of options granted	$ 30.89	$ 38.92	$ 34.39
Weighted average period over which cost is recognized, restricted stock (years)	3 years 1 month 6 days
Total fair value of restricted stock grants	40	43	19
Total fair value of shares vested	20	14	13
Stock-based compensation costs - expensed	10	7	6
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for stock awards from grant date	3 years
Deferred tax benefit (liability) recorded	51	45
Stock-based compensation costs - expensed	25	3	19
Equity-Classified Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred tax benefit (liability) recorded	2
Unrecognized compensation cost related to the Company's unvested stock option grants, restricted stock grants, and performance units	24
Weighted average period over which cost is recognized, years	3 years
Weighted-average grant-date fair value of options granted	$ 40.44
Stock-based compensation costs - expensed	$ 3
Maximum [Member] \| 2004 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum shares	20,500,000

Total fair value of restricted stock grants

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As of the latest balance sheet date presented, the total compensation cost related to outstanding, nonvested share-based compensation awards not yet recognized (will be recogized as services are performed or other vesting criteria are met).

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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