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

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Number of additional shares authorized for issuance under share-based payment arrangement.

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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Stock-Based Compensation - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended		85 Months Ended	198 Months Ended
	May 31, 2021	May 31, 2014	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	May 31, 2021	Jun. 30, 2021	Dec. 31, 2020	May 20, 2020	May 19, 2020	Dec. 31, 2008	Dec. 31, 2004
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 1,106	$ 1,292	$ 2,114	$ 2,927
Stock-based compensation expense to be recognized through results of operations			$ 4,684		$ 4,684			$ 4,684
Employee Stock Award Plan-2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance (in shares)			1,234,701		1,234,701			1,234,701	700,680			1,900,000
Additional shares authorized (in shares)	650,000	1,500,000			650,000		2,150,000
Employee Stock Award Plan-2008 \| Options Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period					10 years
Employee Stock Award Plan-2008 \| Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage					20.00%
Employee Stock Award Plan-2008 \| Share-based Compensation Award, Tranche One \| Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					3 years
Employee Stock Award Plan-2008 \| Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage					33.30%
Employee Stock Award Plan-2008 \| Share-based Compensation Award, Tranche Two \| Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					5 years
Director Plan - 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance (in shares)			144,352		144,352			144,352	160,135	450,000	300,000		300,000
Additional shares authorized (in shares)					0			150,000