Investment Securities Table (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Current	$ 21,863		$ 37,329
Debt Securities, Available-for-sale, Noncurrent	2,017		2,025
Debt Securities, Available-for-sale, Amortized Cost	23,880		39,354
Debt Securities, Available-for-sale, Unrealized Loss	0	$ 0
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value	21,863		37,329
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value	2,017		2,025
Debt Securities, Available-for-sale	23,880		39,354
Available-for-sale Debt Security Current [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		0
Available-for-sale Debt Security Noncurrent [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0		$ 0

Amortized cost 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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