Description of Business and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Summary of Fair Value Hierarchy for Financial Assets

The Company’s fair value hierarchy for its cash equivalents and marketable securities as of December 31, 2017 and 2016, respectively, was as follows:

December 31, 2017	Level 1		Level 2		Level 3		Total
Money market securities	$	2,197	$	—	$	—	$	2,197
Commercial paper		—		49,834		—		49,834
Federal agency notes		—		10,715		—		10,715
U.S. treasuries		—		1,996		—		1,996
Corporate notes		—		1,934		—		1,934
Total	$	2,197	$	64,479	$	—	$	66,676

December 31, 2016	Level 1		Level 2		Level 3		Total
Money market securities	$	1,218	$	—	$	—	$	1,218
Federal agency notes		—		16,810		—		16,810
Commercial paper		—		16,757		—		16,757
Corporate notes		—		15,753		—		15,753
Pre-refunded municipal bonds (1)		—		6,716		—		6,716
U.S. treasuries		—		2,515		—		2,515
Total	$	1,218	$	58,551	$	—	$	59,769

(1) Pre-refunded municipal bonds are collateralized by U.S. treasuries.

Summary of Fair Value Maturities for Financial Asset

The fair value maturities of the Company’s cash equivalents and marketable securities as of December 31, 2017 are as follows:

	Maturities by Period
	Total		Lessthan 1 year		1-5 years		5 - 10 years		More than 10 years
Cash equivalents and marketable securities	$	66,676	$	66,676	$	—	$	—	$	—