Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Summary of the Levels of the Fair Value Hierarchy into Which the Company's Financial Assets Fall

The following table summarizes the levels of the fair value hierarchy into which the Company’s financial assets fall as of March 31, 2019:

	Total		Level 1			Level 2			Level 3
Financial assets:
Included in cash and cash equivalents
Government securities money market		36,429		—				36,429		—
Investments
U.S. treasury instruments		9,273			9,273		—			—
Common stock		191			191		—				—
Total financial assets	$	45,893	$		9,464	$		36,429	$		—

The following table summarizes the levels of the fair value hierarchy into which the Company’s financial assets fall as of December 31, 2018:

	Total		Level 1			Level 2			Level 3
Financial assets:
Included in cash and cash equivalents
U.S. treasury instruments		110,529			100,500			10,029		—
Government securities money market		90,866		—				90,866		—
Investments
Government debt securities (1)		1,105			—			1,105			—
U.S. treasury instruments		79,395			7,977			71,418		—
Common stock		150			150		—				—
Total financial assets	$	282,045	$		108,627	$		173,418	$		—

(1) Consists of municipal bonds and agency bonds.