Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | |
|---|---|---|---|
Sep. 30, 2019 |
Dec. 31, 2019 |
Dec. 31, 2020 |
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| Assets and liabilities measured at fair value on a recurring basis | |||
| Marketable securities in deferred compensation plan | $ 3,060 | $ 3,027 | |
| Fair Value, Recurring | Deferred compensation plan | Trustees and Management | |||
| Assets and liabilities measured at fair value on a recurring basis | |||
| Maximum percentage of participants' compensation which is deferrable (as a percent) | 100.00% | ||
| Marketable securities in deferred compensation plan | $ 3,100 | $ 3,000 | |
| Fair Value, Nonrecurring | Frederick, Maryland | |||
| Assets and liabilities measured at fair value on a recurring basis | |||
| Impairment losses | $ 327 |
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- Definition Represents the maximum percentage of participants' compensation that is deferrable by participants under the deferred compensation plan. No definition available.
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- Definition Carrying amount as of the balance sheet date of assets held under deferred compensation agreements. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition The charge against earnings in the period to reduce the carrying amount of real property to fair value. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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