Stock-Based Compensation - Assumptions Used to Calculate Fair Value of Options (Details) - $ / shares	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Weighted average assumptions
Dividend yield	0.00%
Options
Weighted average assumptions
Dividend yield	0.00%	0.00%
Weighted average fair value (in dollars per share)	$ 35.10	$ 26.55
Options \| Minimum
Weighted average assumptions
Expected life	5 years 6 months	5 years 6 months
Expected volatility	42.30%	47.70%
Risk-free interest rate	0.36%	1.87%
Options \| Maximum
Weighted average assumptions
Expected life	6 years 3 months	6 years 3 months
Expected volatility	49.30%	50.60%
Risk-free interest rate	1.42%	2.63%

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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

Price of a single share of a number of saleable stocks of a company.

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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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