Stock Compensation Plans (Narrative) (Details) - $ / shares shares in Millions	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Stock awards
Stock rights, weighted-average grant date fair value	$ 201.85
Stock awards, vested in the period	0.3	0.2
Stock awards, transferred for employee withholding taxes	0.1	0.1
Restricted performance stock rights
Stock awards
Stock rights, granted	0.1	0.1
Stock rights, weighted-average grant date fair value	$ 210.26	$ 260.69
Restricted performance stock rights \| Minimum
Stock awards
Restricted performance stock rights ultimate vesting percentage	0.00%
Restricted performance stock rights \| Maximum
Stock awards
Restricted performance stock rights ultimate vesting percentage	200.00%

Ultimate vesting percentages based on continued performance targets.

No definition available.

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- Definition

Number of shares transferred by employees to the company during the period to satisfy minimum tax obligations resulting from share-based compensation arrangements.

+ References

No definition available.

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- Definition

Stock Awards [Abstract]

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No definition available.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ 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)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

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

+ 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)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

Net number of non-option equity instruments granted to participants.

+ 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)(1)(iv)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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