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Fair Value Disclosures - Financial instruments measured at fair value on recurring basis (Details) - Fair value on a recurring basis - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Assets: |  |
Available-for-sale securities - equity securities | $ 132 | $ 237
Investments measured at net asset value - trading securities | 32,039 | 28,476
Level 1 |  |
Assets: |  |
Available-for-sale securities - equity securities | 132 | 237
Level 2 |  |
Assets: |  |
Available-for-sale securities - equity securities | 0 | 0
Level 3 |  |
Assets: |  |
Available-for-sale securities - equity securities | $ 0 | $ 0

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details
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- References No definition available. + Details
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
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