Stockholders' Equity - Stock Compensation - Performance-Based Restricted Stock Units - Fair Value Assumptions (Details) - Performance Based Restricted Stock Units ("PSUs") - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assumptions
Weighted average estimated fair value of the PSUs granted (in dollars per share)	$ 76.88	$ 101.82	$ 141.61
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Risk-free interest rate (as a percent)	0.68%	2.35%	2.37%
Expected volatility, minimum (as a percent)	20.00%	58.00%	20.00%
Expected volatility, maximum (as a percent)	70.00%	82.00%	82.00%
Arithmetic Average
Fair Value Assumptions
Expected volatility (as a percent)	35.00%	78.00%	35.00%

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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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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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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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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-Publisher FASB
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- Definition

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

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