Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

The following tables summarize the fair value of financial assets and liabilities that are measured at fair value and the classification by level of input within the fair value hierarchy:

	FAIR VALUE MEASUREMENTS AS OF MARCH 31, 2018
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents:
Cash and money market funds	$	237,514	$	—	$	—	$	237,514
Commercial paper	—		11,987		—		11,987
Total cash and cash equivalents	$	237,514	$	11,987	$	—	$	249,501
Investments:
Commercial paper	$	—	$	44,209	$	—	$	44,209
Corporate bonds	—		40,267		—		40,267
Total investments	$	—	$	84,476	$	—	$	84,476
Total cash, cash equivalents and investments	$	237,514	$	96,463	$	—	$	333,977

	FAIR VALUE MEASUREMENTS AS OF DECEMBER 31, 2017
(in thousands)	Level 1		Level 2		Level 3		Total
Cash and cash equivalents:
Cash and money market funds	$	197,569	$	—	$	—	$	197,569
Total cash and cash equivalents	$	197,569	$	—	$	—	$	197,569
Investments:
Commercial paper	$	—	$	30,883	$	—	$	30,883
Corporate bonds	—		21,203		—		21,203
Total investments	$	—	$	52,086	$	—	$	52,086
Total cash, cash equivalents and investments	$	197,569	$	52,086	$	—	$	249,655