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Restricted Stock Units Issued (Detail) - Restricted Stock Units (RSUs) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Restricted Stock Units
Beginning Restricted Stock Units	61,789	52,224
Restricted Stock Units Granted	6,943	7,892
Dividend Equivalents Earned	1,632	1,673
Restricted Stock Units Settled	0	0
Ending Restricted Stock Units	70,364	61,789
Weighted-Average Stock Price
Beginning Restricted Stock Units	$ 38.25	$ 36.22
Restricted Stock Units Granted	63.50	49.63
Dividend Equivalents Earned	58.15	47.85
Restricted Stock Units Settled
Ending Restricted Stock Units	$ 41.20	$ 38.25

X

- 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

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)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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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.

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- Definition

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- Definition

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