Fair Value Of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Of Financial Instruments [Abstract]

Schedule Of Available-For-Sale Securities

		December 31, 2018
		Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	8,481		—		(1)	$	8,480
Total assets measured at fair value	$	8,481	$	—	$	(1)	$	8,480

		December 31, 2017
		Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Commercial paper	$	7,216	$	—	$	(6)	$	7,210
Corporate bonds		19,524		—		(33)		19,491
Asset-backed securities		7,994		—		(12)		7,982
Total assets measured at fair value	$	34,734	$	—	$	(51)	$	34,683

Schedule Of Contractual Maturities

	December 31,
Investments	2018		2017
Due in one year	$	8,480	$	30,096
Due in one to two years		—		4,587
Total	$	8,480	$	34,683

Fair Value Of Financial Assets Measured On A Recurring Basis

			December 31, 2018
Assets	Classification		Level 1		Level 2		Level 3		Total
Money market funds	Cash and cash equivalents	$	50,703		—		—	$	50,703
U.S. Treasury Securities	Investments		—		8,480		—		8,480
Total assets measured at fair value		$	50,703	$	8,480	$	—	$	59,183

			December 31, 2017
Assets	Classification		Level 1		Level 2		Level 3		Total
Money market funds	Cash and cash equivalents	$	2,758	$	—	$	—	$	2,758
Commercial paper	Investments		—		7,210		—		7,210
Corporate bonds	Investments		—		19,491		—		19,491
Asset-backed securities	Investments		—		7,982		—		7,982
Total assets measured at fair value		$	2,758	$	34,683	$	—	$	37,441