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

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

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Share-Based Compensation (Details) - USD ($)	3 Months Ended						9 Months Ended
Share-Based Compensation (Details) - USD ($)	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based Compensation Expense	$ 900,000			$ 1,000,000.0			$ 2,600,000	$ 1,800,000
Unamortized portion of the estimated fair value of non-vested RSAs and PSUs	4,100,000						$ 4,100,000
Weighted average period expected to be recognized							1 year 4 months 24 days
Amount paid to restricted stock award holders under distribution equivalent rights	15,000	$ 12,000	$ 42,000	43,000	$ 56,000	$ 15,000
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Amount paid to restricted stock award holders under distribution equivalent rights	$ 100,000			$ 100,000			$ 100,000	$ 100,000
Class A common stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate common stock available for issuance	8,600,000						8,600,000