Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Assets Measured at Fair Value on Recurring Basis

The following table presents our fair value hierarchy for our assets measured at fair value on a recurring basis as of March 31, 2019 (in thousands): 

	Level 1		Level 2		Total
Cash equivalents:
Money market funds	$	330,113	$	—	$	330,113
Commercial paper	—		67,733		67,733
Certificates of deposit	—		15,351		15,351
Marketable securities:
Commercial paper	—		137,618		137,618
Corporate notes and bonds	—		1,407,972		1,407,972
Certificates of deposit	—		60,380		60,380
U.S. government and agency securities	—		91,054		91,054
Total	$	330,113	$	1,780,108	$	2,110,221

The following table presents our fair value hierarchy for our assets measured at fair value on a recurring basis as of December 31, 2018 (in thousands): 

	Level 1		Level 2		Total
Cash equivalents:
Money market funds	$	229,047	$	—	$	229,047
Commercial paper	—		16,961		16,961
Certificates of deposit	—		2,465		2,465
Marketable securities:
Commercial paper	—		108,061		108,061
Corporate notes and bonds	—		1,229,714		1,229,714
Certificates of deposit	—		73,585		73,585
U.S. government and agency securities	—		102,214		102,214
Total	$	229,047	$	1,533,000	$	1,762,047