Stock-Based Compensation - Restricted stock units activity (Details) - Restricted Stock Units $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($) $ / shares shares
Number of shares
Non vested outstanding at beginning of period \| shares	6,066
Restricted stock units granted (in shares) \| shares	125
Non vested at end of period \| shares	6,191
Weighted-average grant date fair value
Non vested outstanding at beginning of period (per share) \| $ / shares	$ 16.49
Restricted stock units granted (per share) \| $ / shares	58.06
Non vested outstanding at end of period (per share) \| $ / shares	$ 17.32
Total unrecognized stock-based compensation expense \| $	$ 0.1
Weighted-average period over which unrecognized stock-based compensation expense is expected to be recognized	26 days

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 nonvested award under share-based payment arrangement. Excludes share and unit options.

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- Definition

The number of grants made 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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- Definition

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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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-Publisher FASB
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