Balance Sheet Components (Tables)

6 Months Ended

Jun. 30, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Cash and cash equivalents consisted of the following (in thousands):

	June 30, 2018		December 31, 2017
Cash	$	63,516	$	103,716
Money market funds		580,287		569,942
Total cash and cash equivalents	$	643,803	$	673,658

Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments

The Company’s investments consist of available-for-sale debt investments and marketable equity investments. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s available-for-sale investments by major investments type are summarized in the tables below (in thousands):

	June 30, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
Corporate bonds	$	28,132	$	—	$	(38	)	$	28,094
Bond and mutual funds		10,341		36		—			10,377
Equity investments		126		84		—			210
Total investments	$	38,599	$	120	$	(38	)	$	38,681

	December 31, 2017
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
Corporate bonds	$	53,985	$	4	$	(46	)	$	53,943
Bond and mutual funds		17,249		1,153		—			18,402
Equity investments		126		95		—			221
Total investments	$	71,360	$	1,252	$	(46	)	$	72,566

Schedule of Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	June 30, 2018		December 31, 2017
Preclinical and clinical trial accruals	$	23,893	$	32,321
Payroll and related accruals		12,631		18,810
Property taxes and other		1,843		4,201
Professional services		2,370		1,991
Other		8,755		6,458
Total accrued liabilities	$	49,492	$	63,781