Marketable Securities - Schedule of Marketable Securities by Category (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 62,681	$ 109,750
Gross Unrealized Holding Gains	43	0
Gross Unrealized Holding Losses	40	161
Fair Value	62,684	109,589
Municipal Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	62,681	109,750
Gross Unrealized Holding Gains	43	0
Gross Unrealized Holding Losses	40	161
Fair Value	$ 62,684	$ 109,589

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) 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, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) 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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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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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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-Publisher FASB
-Name Accounting Standards Codification
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