Balance Sheet Components (Schedule of Available-for-Sale Short-Term Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Cost	$ 1,475	$ 70,479
Unrealized Gains	0	1
Unrealized Losses	0	(17)
Estimated Fair Value	1,475	70,463
U.S. treasuries
Debt Securities, Available-for-sale [Line Items]
Cost	0	70,330
Unrealized Gains	0	1
Unrealized Losses	0	(17)
Estimated Fair Value	0	70,314
Certificates of deposits
Debt Securities, Available-for-sale [Line Items]
Cost	149	149
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	149	149
Convertible debt
Debt Securities, Available-for-sale [Line Items]
Cost	1,326	0
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	$ 1,326	$ 0

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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