Stock Compensation Plans, Weighted Average Assumptions Used in Valuing Stock Options Granted (Details) - Stock Options [Member]	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted average assumptions used in valuing stock options [Abstract]
Risk-free interest rate	2.57%	1.89%	1.23%
Expected dividend yield	0.00%	0.00%	0.00%
Expected life	5 years	5 years	5 years
Expected price volatility	14.44%	22.88%	28.41%

No definition available.

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- Definition

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.

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- Definition

Weighted average expected volatility rate of share-based compensation awards.

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the 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
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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