Stock-Based Compensation - Narrative (Details) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares received for each RSU upon vesting	1
Shares reserved for issuance under long-term incentive plans	15,000,000
Pre-tax stock-based compensation expense	$ 39,000,000	$ 35,000,000	$ 34,000,000
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 20.02	$ 20.58	$ 15.14
Aggregate intrinsic value of options exercised	$ 89,000,000	$ 55,000,000	$ 115,000,000
Cash receipts from exercise of options	84,000,000	59,000,000	148,000,000
Total fair value of vested stock option awards	12,000,000	13,000,000	16,000,000
Total fair value of vested restricted stock unit awards	$ 21,000,000	20,000,000	27,000,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period	10 years
Total unrecognized compensation cost related to unvested awards	$ 7,000,000
Weighted-average period to recognize total unrecognized compensation cost	1 year 10 months 25 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested awards	$ 16,000,000
Weighted-average period to recognize total unrecognized compensation cost	1 year 7 months 6 days
Periodic Vesting \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Cliff Vesting \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Cliff Vesting \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Discontinued Operations
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation expense	$ 0	$ 0	$ 5,000,000

Number of shares for each vested RSU or PRSU award.

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- Definition

Share based compensation arrangement by share based payment award equity instruments stock options vested in period fair value.

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- Definition

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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-Publisher FASB
-Name Accounting Standards Codification
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Aggregate number of common shares reserved for future issuance.

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Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

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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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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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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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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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- Definition

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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