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Fair Value Measurements - Schedule of Changes in Level 3 Investments (Details) - USD ($) $ in Thousands | 9 Months Ended
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Sep. 30, 2019 | Sep. 30, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Dividend income from investments in preferred stock | $ 38 | $ 14,575
Significant Unobservable Inputs (Level 3) |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Beginning balance | 191 |
Retained interest in deconsolidated subsidiary | 14,239 |
Dividend income from investments in preferred stock | 38 |
Net unrealized appreciation in the fair value of the investments in equity securities and preferred stock | 2,242 |
Ending balance | $ 16,710 |

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- Definition Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Increase Due to Deconsolidation of Subsidiary + References No definition available. + Details
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- Definition Amount of dividend income included in net income that results in no cash flow. + References No definition available. + Details
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