Earnings Per Share (Details)	12 Months Ended
Dec. 31, 2018 $ / shares shares
Shares of Common Stock Attributable to Options
Outstanding at beginning of period (in shares) \| shares	0
Granted (in shares) \| shares	421,297
Exercised (in shares) \| shares	0
Forfeited or expired (in shares) \| shares	0
Outstanding at end of period (in shares) \| shares	421,297
Exercisable (in shares) \| shares	58,766
Weighted-Average Exercise Price of Options
Outstanding at beginning of period (usd per share) \| $ / shares	$ 0.00
Granted (usd per share) \| $ / shares	31.61
Exercised (usd per share) \| $ / shares	0.00
Forfeited or expired (usd per share) \| $ / shares	0.00
Outstanding at end of period (usd per share) \| $ / shares	31.61
Exercisable (usd per share) \| $ / shares	$ 31.61

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Gross number of share options (or share units) granted during the period.

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No definition available.

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Number of options outstanding, including both vested and non-vested options.

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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
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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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No definition available.

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Number of share options (or share units) exercised during the current period.

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