Director Deferred Stock Ownership Plan Amount to be credited to deferred stock accounts.

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- Definition

Share Delivery Term if Elected

+ References

No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Award Cost Recognition Period

+ References

No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Compensation Costs Recognized

+ References

No definition available.

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- Definition

Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 20
-Section 55
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=96864182&loc=d3e11374-113907

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

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.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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Stock-Based Compensation - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Director deferred stock ownership plan amount to be credited to deferred stock accounts	50.00%
Share delivery term if elected	5 years
Award vesting period	3 years
Shares, granted (in shares)		0
Total fair value of stock options, vested	$ 4	$ 7	$ 11
Employee withholding tax on share-based payments	$ (49)	$ (55)	$ (92)
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Award expiration period	10 years
Employee Stock Option \| Graded Vesting Method
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Employee Stock Option \| Ratable Vest One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award cost recognition period	12 months
Percentage of compensation costs recognized	33.33%
Employee Stock Option \| Ratable Vest Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award cost recognition period	24 months
Percentage of compensation costs recognized	33.33%
Employee Stock Option \| Ratable Vest Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award cost recognition period	36 months