Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Schedules of concentration of risk

Customers with revenues of 10% or more of the Company's total revenues consist of the following:

	Percentage of Total Revenues For The Years Ended December  31,
	2013		2012		2011
Customers:
Merck	39	%	13	%	10	%
Exela	15	%	—	%	—	%
Novartis	14	%	1	%	1	%
Shell	—	%	51	%	51	%

Schedule of allowance for doubtful accounts

The following is a summary of activity in the Company's allowance for doubtful accounts for the three years ended December 31, 2013, 2012 and 2011 (in thousands):

	Years ended December 31,
	2013			2012			2011
Allowance - beginning of period	$	(150	)	$	(17	)	$	(58	)
Provisions for doubtful accounts	(386		)	(133		)	41
Recoveries from bad debts	76			—			—
Write-off and other	—			—			—
Allowance - end of period	$	(460	)	$	(150	)	$	(17	)

Schedule of estimated ranges of useful lives of property and equipment

Depreciation is calculated using the straight-line method over the following estimated ranges of useful lives:

Asset classification	Estimated useful life
Laboratory equipment	5 years
Computer equipment and software	3 to 5 years
Office equipment and furniture	5 years
Leasehold improvements	Lesser of useful life or lease term

Property and Equipment, net

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

	December 31,
	2013			2012
Laboratory equipment	$	23,949		$	33,776
Leasehold improvements	9,493			4,388
Computer equipment and software	3,196			11,099
Office equipment and furniture	1,228			1,531
Construction in progress (1)	41			28
	37,907			50,822
Less: accumulated depreciation and amortization	(29,461		)	(34,172		)
Property and equipment, net	$	8,446		$	16,650

(1) Construction in progress includes equipment received but not yet placed into service pending installation.

Schedule of calculation of basic and diluted net loss per share of common stock

The following table presents the calculation of basic and diluted net loss per share of common stock (in thousands, except per share amounts):

	Years Ended December 31,
	2013			2012			2011
Numerator:
Net loss	$	(41,303	)	$	(30,857	)	$	(16,550	)
Denominator:
Weighted-average shares of common stock outstanding	38,231			36,768			35,674
Weighted-average shares of common stock used in computing net loss per share, basic and diluted	38,231			36,768			35,674
Net loss per share, basic and diluted	$	(1.08	)	$	(0.84	)	$	(0.46	)

Securities not included in the net loss per common share calculations

The following options to purchase common stock, restricted stock units, performance stock units and warrants to purchase common stock were excluded from the computation of diluted net loss per share of common stock for the periods presented because including them would have had an anti-dilutive effect (in thousands):

	Years Ended December 31,
	2013	2012	2011
Options to purchase common stock	4,126	6,133	7,904
Restricted stock units	2,238	958	546
Performance stock units	358	—	—
Warrants to purchase common stock	75	260	266
Total	6,797	7,351	8,716