Equity Compensation Plans - Assumptions Of Black-Scholes Option Grant (Details) - $ / shares	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Risk-free interest rate	2.30%
Volatility, minimum	98.00%
Volatility, maximum	105.00%
Dividend yield	0.00%	0.00%
Forfeiture rate	11.33%
Weighted average fair value	$ 49.88
Minimum
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (in years)	5 years 3 months
Maximum
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (in years)	6 years 29 days

Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Forfeiture Rate

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- Definition

Share Based Payment Award Stock Options Valuation Assumptions [Line Items]

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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 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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- Definition

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

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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