Stock-based Compensation Plans (Schedule of Stock-based Compensation Arrangements by Share-based Payment Award - LTPP) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at end of period	2,800
Tax benefit realized related to vested awards	$ 35	$ 29	$ 30
Long-Term Performance Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period	584	723	665
Granted	145	117	142
Increase due to expected performance	96	71	193
Vested	(236)	(303)	(273)
Forfeited	(10)	(24)	(4)
Outstanding at end of period	579	584	723
Weighted-average grant date fair value of stock outstanding at beginning of the period	$ 150.15	$ 127.16	$ 110.32
Weighted-average grant date fair value of stock granted	176.13	205.76	152.29
Weighted-average grant date fair value of long-term performance plan stock increase due to expected performance	187.90	135.27	125.14
Weighted-average grant date fair value of stock vested	120.52	112.15	97.59
Weighted-average grant date fair value of stock forfeited	170.42	164.58	137.57
Weighted-average grant date fair value of stock outstanding at the end of the period	$ 174.72	$ 150.15	$ 127.16
Fair value of LTPP awards vested	$ 45	$ 67	$ 44
Tax benefit realized related to vested awards	10	24	15
Excess Tax Benefits Realized	$ 3	$ 13	$ 7
Expected dividend equivalent units [Member] \| Long-Term Performance Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period	33	28
Outstanding at end of period	33	33	28

The weighted average fair value at grant date for the increase/ decrease of nonvested equity-based awards.

No definition available.

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- Definition

The increase (decrease) in number of shares under a share-based incentive award plan.

+ References

No definition available.

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Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=117330312&loc=d3e23163-113944

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- Definition

Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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- Definition

The number of grants made 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).

+ References

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- Definition

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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- 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.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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-Publisher FASB
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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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- Definition

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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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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