Share-Based Payments - Method and Assumptions on Valuation of Stock Options and Awards (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Option Plan
Schedule of Share-based Compensation Assumptions [Line Items]
Expected life (in years)	7 years 8 months 12 days	7 years 10 months 6 days	7 years 7 months 20 days
Volatility	30.89%	30.00%	32.37%
Risk free interest rate	0.70%	1.90%	3.10%
Dividend yield	0.53%	0.76%	0.61%
Weighted-average fair value at the grant date (in dollars per share)	$ 25.93	$ 17.12	$ 21.03
Expected stock volatility rate, low end of range	30.00%	30.00%	31.72%
Expected stock volatility rate, high end of range	39.00%	38.17%	36.73%
Restricted Stock Units (RSUs)
Schedule of Share-based Compensation Assumptions [Line Items]
Volatility	37.39%
Risk free interest rate	0.11%
Dividend yield	0.47%

[Line Items] for Schedule of Share-based Compensation Assumptions [Table]

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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 maximum 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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The estimated measure of the minimum 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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No definition available.

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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

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

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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
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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-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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