4.	Balance Sheet Components

Cash and Cash Equivalents

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

	September 30, 2015		December 31, 2014
Cash	$	95,488	$	151,653
Certificates of deposits		8,468		—
Money market funds		104,694		13,802
Total cash and cash equivalents	$	208,650	$	165,455

Investments

All investments are classified as available-for-sale. The amortized cost, gross unrealized holding gains or losses, and fair value of our available-for-sale investments by major investments type are summarized in the tables below (in thousands):

	September 30, 2015
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Corporate bonds	$	132,302	$	316	$	(179	)	$	132,439
Certificated of deposits		8,217		5		—			8,222
Equity investments		124		62		—			186
Total investments	$	140,643	$	383	$	(179	)	$	140,847

	December 31, 2014
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Corporate bonds	$	158,692	$	254	$	(514	)	$	158,432
Equity investments		124		77		—			201
Total investments	$	158,816	$	331	$	(514	)	$	158,633

At September 30, 2015, all of the available-for-sale investments had contractual maturities within four years. We periodically review our available-for-sale investments for other-than-temporary impairment. We consider factors such as the duration, severity and the reason for the decline in value, the potential recovery period and our intent to sell. For debt securities, we also consider whether (i) it is more likely than not that we will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. During the quarters and nine months ended September 30, 2015 and 2014, we did not recognize any other-than-temporary impairment loss.

At September 30, 2015, a total of $29.2 million of our cash and cash equivalents were held outside of the U.S. in our foreign subsidiaries to be used primarily for our China operations.

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	September 30, 2015		December 31, 2014
Preclinical and clinical trial accruals	$	24,388	$	25,418
Payroll and related accruals		11,480		15,608
Professional services		1,764		2,401
Other		4,142		5,558
Total accrued liabilities	$	41,774	$	48,985