Stock-Based Compensation Plans (Weighted-Average Assumptions for the ESOP) (Details) - $ / shares	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Dividend yield	1.83%	1.98%	1.86%	1.99%
Expected volatility	27.47%	27.72%	27.67%	27.38%
Risk-free interest rate	0.98%	0.28%	0.92%	0.31%
Expected term of options	4 years 1 month 20 days	4 years 1 month 28 days	4 years 1 month 24 days	4 years 1 month 28 days
Weighted average grant-date fair value (in dollars per share)	$ 6.32	$ 4.64	$ 6.49	$ 4.38

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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 estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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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

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.

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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)
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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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