Stockholder's Equity and Stock-Based Compensation Expense - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares issued or committed for issuance under outstanding stock options (in shares)	569,673	700,759
Stock-based compensation expense	$ 1,637	$ 3,736
Restricted Stock and Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares of restricted stock and shares reserved for restricted stock units outstanding (in shares)	762,277	926,917	908,754
Stock Appreciation Rights
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares issued or committed for issuance under outstanding stock options (in shares)	811,415	963,013	954,679
Stock-based compensation expense	$ (1,000)	$ 2,700

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

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

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