Earnings Per Common Share And Share Awards Share-Based Valuation Assumptions (Details) - $ / shares	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	28.50%	30.20%
Interest rate	0.70%	2.30%
Yield rate	1.20%	1.00%
Share-based Compensation Arrangement by Share-based Payment Award, Grants in Period, Weighted Average Grant Date Fair Value	$ 34.45	$ 51.88
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years	6 years 2 months 12 days	7 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years	7 years	7 years

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

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- Definition

Rate of weighted-average expected volatility for award under share-based payment arrangement.

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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

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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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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