Stock-Based Compensation (Narrative) (Details) - USD ($)	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of service for immediate vesting upon death, disability or retirement	3 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
2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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
Expiration period from date of grant	10 years
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 asset (liability) recorded	$ 2,000,000	$ 3,000,000	$ 4,000,000
Unrecognized compensation cost related to the Company's unvested stock option grants, restricted stock grants, and performance units	$ 13,000,000
Weighted average period over which cost is recognized, years	2 years
Weighted-average grant-date fair value of options granted	$ 3.16	$ 10.16	$ 13.39
Stock options, exercised, number of options	0	402,000	833,000
Intrinsic value		$ 4,000,000	$ 22,000,000
Stock-based compensation costs - expensed	$ 5,000,000	5,000,000	5,000,000
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 asset (liability) recorded	$ 11,000,000	(10,000,000)	(15,000,000)
Unrecognized compensation cost related to the Company's unvested stock option grants, restricted stock grants, and performance units	$ 88,000,000
Weighted average period over which cost is recognized, restricted stock (years)	3 years
Total fair value of restricted stock grants	$ 47,000,000	40,000,000	43,000,000
Total fair value of shares vested	29,000,000	20,000,000	14,000,000
Stock-based compensation costs - expensed	$ 14,000,000	10,000,000	7,000,000
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for stock awards from grant date	3 years
Stock-based compensation costs - expensed	$ 31,000,000	25,000,000	3,000,000
Performance unit liability recorded	8,000,000	51,000,000
Equity-Classified Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred tax asset (liability) recorded	4,000,000	2,000,000	$ 0
Unrecognized compensation cost related to the Company's unvested stock option grants, restricted stock grants, and performance units	$ 14,000,000
Weighted average period over which cost is recognized, years	2 years
Stock-based compensation costs - expensed	$ 6,000,000	$ 3,000,000
Maximum [Member] \| 2013 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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Amount of increase (decrease) in additional paid in capital (APIC) resulting from a tax benefit (deficiency) associated with an share-based compensation plan other than an employee stock ownership plan (ESOP).

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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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Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements. Represents currently earned compensation under cash arrangements (such as a profit-sharing plan, rabbi trust, and employee contract--excluding equity-based arrangements) that is not actually paid until a later date.

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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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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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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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

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