Stock-Based Compensation (Flexible Stock Plan Options) (Details) - shares shares in Millions	Dec. 31, 2018	Dec. 31, 2017
Maximum Number of Authorized Shares
Unexercised options	1.6	1.9
Outstanding stock units—unvested	0.8	0.6
Flexible Stock Plan
Shares Available for Issuance
Unexercised options	1.6
Outstanding stock units—vested	3.6
Outstanding stock units—unvested	0.8
Available for grant	7.6
December 31, 2018	13.6
Maximum Number of Authorized Shares
Unexercised options	1.6
Outstanding stock units—vested	7.9
Outstanding stock units—unvested	2.3
Available for grant	7.6
December 31, 2018	19.4

Share-based Compensation Arrangement by Share-based Payment Award, Common Shares Outstanding [Abstract]

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Fully Vested Outstanding

+ References

No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Fully Vested, Outstanding, Prior to Plan Modification

+ References

No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Nonvested Number, Prior to Plan Modification

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No definition available.

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Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized, Prior to Plan Modification

+ References

No definition available.

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Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant, Prior to Plan Modification

+ References

No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding Number, Prior to Plan Modification

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No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Weighted Number of Authorized Common Shares [Abstract]

+ References

No definition available.

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
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- Definition

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).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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