Equity Compensation Plan - Assumptions for Fair Value of Stock-Based Awards (Detail)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
2017 Award Grants
Assumptions:
Dividend yield	13.10%
Expected volatility	27.70%
Risk-free interest rate	3.80%
2017 Award Grants \| $5.66
Assumptions:
Expected lives	10 years
2016 Award Grants
Assumptions:
Dividend yield	13.10%
Expected volatility	27.70%
Risk-free interest rate	3.80%
Expected lives		3 years

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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

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.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 50
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-Publisher FASB
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-Section S99
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-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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