Stockholders' Equity - Sales of the Company's Stock (Details) $ / shares in Units, $ in Millions	1 Months Ended
May 31, 2018 USD ($) $ / shares shares
Sale of Company Stock by Employees and Former Employees
Class of Stock [Line Items]
Common stock sold by employees and former employees (in shares) \| shares	1,300,000
Share price of stock sold by employees (in dollars per shares) \| $ / shares	$ 13.12
Aggregate purchase price	$ 17.2
Stock Compensation Plan
Class of Stock [Line Items]
Excess of purchase price over fair value recognized as compensation expense	$ 2.2

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

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