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Fair Value Measurements - Narrative (Details) - USD ($) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Other-than-temporary impairments | $ 0 | $ 0 | $ 0 | $ 0
Subsidiary unit awards |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Settlements | $ 0 | $ 0 | 200,000 | $ 2,802,000
Founder and President | Subsidiary unit awards | Repurchase of Subsidiary Units, February 2011 |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |
Settlements |  |  | $ 200,000 |

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- Definition Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 8A -URI http://asc.fasb.org/extlink&oid=118954083&loc=SL6284422-111562 + Details
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