Stock Based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value of Stock Options (Details) - shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Additional Disclosures for equity-based plans
Expected Term (in Years)			15 days
Expected Dividend Yield	0.00%	0.00%	0.00%
Shares Issued under ESPP	207,324	175,966	224,928
Minimum
Additional Disclosures for equity-based plans
Expected Volatility	27.00%	27.00%	28.00%
Risk-Free Interest Rate	1.60%	1.42%	0.62%
Maximum
Additional Disclosures for equity-based plans
Expected Volatility	42.00%	37.00%	37.00%
Risk-Free Interest Rate	2.50%	2.50%	1.42%

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

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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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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- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

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