5.	Balance Sheet Components

Cash and Cash Equivalents

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

	December 31,
	2015		2014
Cash	$	75,685	$	151,653
Money market funds		77,639		13,802
Total cash and cash equivalents	$	153,324	$	165,455

Property and Equipment

Property and equipment consisted of the following (in thousands):

	December 31,
	2015			2014
Laboratory equipment	$	18,233		$	17,114
Computer equipment		5,701			5,106
Furniture and fixtures		5,361			5,082
Leasehold improvements		93,380			92,790
Building shell (Refer to Note 8)		53,879			53,879
Construction in progress		193			519
Total property and equipment	$	176,747		$	174,490
Less: accumulated depreciation		(47,727	)		(42,319	)
Property and equipment, net	$	129,020		$	132,171

Depreciation expense for the years ended December 31, 2015, 2014 and 2013 was $5.7 million, $4.5 million, and $5.1 million, respectively.

Investments

All investments are classified as available-for-sale. 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):

	December 31, 2015
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
Corporate bonds	$	126,522	$	54	$	(473	)	$	126,103
Certificate of deposits		8,217		—		(2	)		8,215
Bond and mutual funds		25,052		—		—			25,052
Equity investments		126		71		—			197
Total investments	$	159,917	$	125	$	(475	)	$	159,567

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

The contractual maturities of available-for-sale investments were as follows (in thousands):

	December 31,
	2015
Within one year	$	12,797
After one year through four years		121,521
Total debt investments		134,318
Bond and mutual funds		25,052
Equity investments		197
Total investments		159,567

Available-for-sale investments are reported at fair value and as such, their associated unrealized gains and losses are reported as a separate component of stockholders’ equity within accumulated other comprehensive income (loss).

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	December 31,
	2015		2014
Preclinical and clinical trial accruals	$	27,973	$	25,418
Payroll and related accruals		13,535		15,608
Professional services		1,662		2,401
Other		4,762		5,558
Total accrued liabilities	$	47,932	$	48,985