Summary of Significant Accounting Policies - Summary of Estimated Fair Value of Stock Option Grant on Weighted Average Assumptions (Details) - Time-Based Stock Options	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Weighted-average assumptions
Expected stock volatility, minimum (as a percent)	46.00%	44.00%	43.00%
Expected stock volatility, maximum (as a percent)	50.00%	49.00%	47.00%
Risk-free interest rate, minimum (as a percent)	1.34%	2.25%	1.69%
Risk-free interest rate, maximum (as a percent)	2.59%	3.10%	2.38%
Minimum
Weighted-average assumptions
Expected option term	5 years	5 years	5 years
Maximum
Weighted-average assumptions
Expected option term	7 years	8 years	8 years

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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.

+ References

No definition available.

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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.

+ References

No definition available.

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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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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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 (f)(2)(i)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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