Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Hierarchy

The following table represents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value (in thousands):

	Fair Value at March 31, 2018						Fair Value at December 31, 2017
	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
Assets
Money market funds(1)	$	31,056	$	—	$	—	$	36,762	$	—	$	—
Asset-backed securities(2)		—		28,496		—		—		29,750		—
Corporate debt securities(3)		—		70,760		—		—		80,309		—
Total assets	$	31,056	$	99,256	$	—	$	36,762	$	110,059	$	—
Liabilities
Convertible notes payable	$	—	$	228,621	$	—	$	—	$	152,396	$	—

(1) Classified as cash and cash equivalents as of March 31, 2018 and December 31, 2017, respectively (see Note 3).

(2) Includes $18,750 and $16,007 classified as cash and cash equivalents as of March 31, 2018 and December 31, 2017, respectively (see Note 3).

(3) Includes $50,148 and $43,056 classified as cash and cash equivalents as of March 31, 2018 and December 31, 2017, respectively (see Note 3).