Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Available for sale securities, aggregate cost			$ 3,400
Available-for-sale securities, unrealized gains		$ 100	700
Fair value of available for sale securities			4,100
Available for sale securities distributed		3,300
Proceeds from sale of equity securities	$ 0	933	17,896
Gain on sale and distribution of equity securities	$ 0	$ 823	$ (4,222)

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with interest rate reset through auction process, sold at par value.

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Amount of unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of gain (loss) on sale or disposal of equity in securities of subsidiaries or equity method investee.

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Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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