Common Stock and Stockholders' Equity - Fair Value Assumptions (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other disclosures
Compensation expense	$ 21,928	$ 17,368	$ 40,243	$ 30,891
Stock options
Fair value assumptions
Volatility, minimum (as a percent)			46.10%	46.90%
Volatility, maximum (as a percent)			51.00%	47.60%
Expected life (in years)			4 years 3 months 18 days	5 years 2 months 12 days
Risk-free interest rate, minimum			0.27%	1.75%
Risk-free interest rate, maximum			1.64%	2.55%
Dividend yield (as a percent)			0.00%	0.00%
Weighted-average fair value of the underlying stock options			$ 49.44	$ 27.34
Other disclosures
Compensation expense	4,200	$ 5,200	$ 8,100	$ 10,700
Unrecognized compensation cost	$ 16,400		$ 16,400
Period over which unrecognized compensation cost is expected to be recognized			1 year 9 months 18 days

The weighted-average fair value of the underlying stock options.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Weighted-average period over which cost not yet recognized is expected to be recognized for 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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Amount of cost to be recognized for option under share-based payment arrangement.

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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 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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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
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