Relypsa (RLYP) 10-Q 11 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Aug. 01, 2014
Document And Entity Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'RLYP	'
Entity Registrant Name	'Relypsa Inc	'
Entity Central Index Key	'0001416792	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	33,996,807

Condensed_Balance_Sheets

Condensed Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$120,951	$94,759
Short-term investments	39,442	'
Restricted cash	268	'
Other receivables	117	241
Prepaid expenses and other current assets	1,039	1,657
Total current assets	161,817	96,657
Restricted cash	686	'
Property and equipment, net	6,143	5,624
Intangible assets	6	14
Other assets	3,325	3,736
Total assets	171,977	106,031
Current liabilities:	'	'
Accounts payable	4,215	4,736
Accrued payroll and related expenses	2,181	1,794
Accrued liabilities	3,525	5,947
Deferred rent, current portion	4,334	640
Line of credit, current portion	875	408
Capital loan, current portion	705	4,304
Total current liabilities	15,835	17,829
Long-term liabilities:	'	'
Deferred rent, long-term	968	4,394
Line of credit	'	630
Capital loan	13,979	8,328
Total liabilities	30,782	31,181
Commitments and contingencies	'	'
Stockholders’ equity:	'	'
Preferred stock: $0.001 par value; 5,000 shares authorized at June 30, 2014 and December 2013; no shares issued and outstanding at June 30, 2014 and December 31, 2013	'	'
Common stock: $0.001 par value; 300,000 shares authorized at June 30, 2014 and December 31, 2013; 33,912 and 29,710 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively	34	30
Additional paid-in capital	399,800	300,660
Accumulated other comprehensive income	6	'
Accumulated deficit	-258,645	-225,840
Total stockholders’ equity	141,195	74,850
Total liabilities and stockholders’ equity	$171,977	$106,031

Condensed_Balance_Sheets_Paren

Condensed Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, except Per Share data, unless otherwise specified
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	300,000	300,000
Common stock, shares issued	33,912	29,710
Common stock, shares outstanding	33,912	29,710

Condensed_Statements_of_Operat

Condensed Statements of Operations (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating expenses:	'	'	'	'
Research and development	$11,075	$13,295	$21,976	$35,899
General and administrative	5,322	2,988	10,125	5,523
Total operating expenses	16,397	16,283	32,101	41,422
Loss from operations	-16,397	-16,283	-32,101	-41,422
Interest and other income (expense), net	36	-3,549	64	-4,413
Interest expense	-376	-388	-768	-636
Net loss	($16,737)	($20,220)	($32,805)	($46,471)
Net loss per share, basic and diluted	($0.51)	($64.87)	($1.04)	($149.42)
Weighted average common shares used to compute net loss per share, basic and diluted	33,141,384	311,703	31,435,378	311,015

Condensed_Statements_of_Compre

Condensed Statements of Comprehensive Loss (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net loss	($16,737)	($20,220)	($32,805)	($46,471)
Other comprehensive income (loss):	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, net of tax	2	-10	6	-21
Total comprehensive loss	($16,735)	($20,230)	($32,799)	($46,492)

Condensed_Statements_of_Cash_F

Condensed Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Operating activities	'	'
Net loss	($32,805)	($46,471)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation and amortization	559	571
Stock-based compensation	4,063	840
Amortization of debt issuance costs	16	13
Amortization of debt discount	75	57
Accretion of final debt payment	159	151
Accrued interest on capital loan	71	'
Investment premium amortization	312	'
Revaluation of convertible preferred stock warrant liability	'	4,470
Changes in assets and liabilities:	'	'
Other receivables	124	2,983
Prepaid expenses and other current assets	602	244
Other assets and restricted cash	-544	-225
Accounts payable	-521	2,290
Accrued and other liabilities	-2,035	2,334
Deferred rent	268	622
Net cash used in operating activities	-29,656	-32,121
Investing activities	'	'
Purchase of short-term investments	-49,984	-10,142
Proceeds from maturities of short-term investments	10,236	31,056
Purchase of property and equipment	-1,069	-3,513
Net cash (used in) provided by investing activities	-40,817	17,401
Financing activities	'	'
Net proceeds from public offerings	94,607	'
Proceeds from common stock option exercise	240	5
Net proceeds from capital loan	3,549	12,404
Repayment of capital loan	-1,530	'
Net proceeds from equipment line of credit	'	1,225
Repayment of equipment line of credit	-201	-33
Net cash provided by financing activities	96,665	13,601
Net increase (decrease) in cash and cash equivalents	26,192	-1,119
Cash and cash equivalents at beginning of period	94,759	15,221
Cash and cash equivalents at end of period	120,951	14,102
Noncash investing and financing activities	'	'
Change in unrealized (loss) gain on short-term investments	6	-21
Line of Credit	'	'
Noncash investing and financing activities	'	'
Issuance of warrants	'	25
Capital Loan	'	'
Noncash investing and financing activities	'	'
Issuance of warrants	$234	$193

Description_of_Business_and_Si

Description of Business and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2014
Description of Business and Significant Accounting Policies	'
	1.  Description of Business and Significant Accounting Policies
	Organization
	Relypsa, Inc. (Relypsa or the Company) is a biopharmaceutical company dedicated to the development and commercialization of new non-absorbed polymeric drugs for important applications in renal, cardiovascular and metabolic disease. The Company commenced operations on October 29, 2007. The Company’s principal operations are based in Redwood City, California and it operates in one segment.
	The information included in this quarterly report on Form 10-Q should be read in conjunction with the financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 filed with the U.S. Securities Exchange Commission (SEC).
	On April 16, 2014, the Company completed an underwritten public offering of 4,130,611 shares of common stock at an offering price of $24.50 per share. The Company received aggregate net proceeds of $94.6 million, after deducting the underwriting discounts and offering related transaction costs.
	Basis of Presentation
	There have been no material changes to the Company’s significant accounting policies during the six months ended June 30, 2014 as compared to the significant accounting policies described in the Company’s audited financial statements included in the Company’s Annual Report on Form 10-K filed with the SEC for the year ended December 31, 2013.
	The accompanying financial information for the three and six months ended June 30, 2014 is unaudited. These unaudited interim condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP and applicable rules and regulations of the SEC regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. In management’s opinion, the unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013, and include all adjustments, which include only normal recurring adjustments necessary for the fair presentation of our statement of financial position as of June 30, 2014, our statements of operations and comprehensive loss for the three and six months ended June 30, 2014 and our statements of cash flows for the six months ended June 30, 2014. The results for the three and six months ended June 30, 2014 are not necessarily indicative of the results expected for the full fiscal year or any other period(s).
	Use of Estimates
	The preparation of these unaudited interim condensed financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of assets and liabilities, income taxes, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
	Recent Accounting Pronouncements
	On June 10, 2014, FASB issued Accounting Standards Update No. 2014-10, Development Stage Entities: Elimination of Certain Financial Reporting Requirements. The update removes the definition of a development stage entity from FASB ASC 915 and eliminates the requirement for development stage entities to present inception-to-date information on the statements of operations, cash flows and stockholders’ deficit. The Company early adopted this standard for the period covered by the report herein.
	Liquidity
	In the course of its development activities, the Company has sustained significant operating losses and expects such losses to continue over the next few years. The Company’s success depends on the outcome of its research and development activities. From inception through June 30, 2014, the Company has incurred cumulative net losses of $248.9 million. Management expects to incur additional losses in the future to conduct product research and development and commercialization activities. Additional funding will be needed to support the planned commercial launch in the United States and as the Company builds out its sales capabilities. The Company intends to raise such funding through the issuance of additional equity, debt financings or other sources, such as strategic collaborations. However, if such financing is not available at adequate levels or on acceptable terms, the Company could be required to significantly reduce operating expenses and delay, reduce the scope of or eliminate some of its development programs or its commercialization efforts, enter into a collaboration or other similar arrangement with respect to commercialization rights to patiromer or any of its other product candidates, out-license intellectual property rights to patiromer or its other product candidates and sell unsecured assets, or a combination of the above, which may have a material adverse effect on the Company’s business, results of operations, financial condition and/or its ability to fund its scheduled obligations on a timely basis or at all.
	Cash Equivalents
	The Company considers all highly liquid investments purchased with original maturities of 90 days or less at the date of purchase to be cash equivalents.
	Short-Term Investments
	Short-term investments consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of acquisition. Short-term investments are carried at fair value based upon quoted market prices or pricing models for similar securities. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of accumulated comprehensive income (loss). Realized gains or losses on the sale of all such securities are reported in interest and other income (expense), net and computed using the specific identification method.
	Restricted Cash
	Restricted cash related to the Company’s leases consists of irrevocable letters of credit that are collateralized by a restricted deposits held at the Company’s bank over a term that is consistent with the corresponding lease.
	Research and Development Expenses
	Research and development costs are charged to expense as incurred and consist of costs incurred to further the Company’s research and development activities including salaries and related employee benefits, costs associated with clinical trials, nonclinical research and development activities, regulatory activities, research-related overhead expenses and fees paid to external service providers and contract research and manufacturing organizations that conduct certain research and development activities on behalf of the Company.
	Clinical Trial Accruals
	Clinical trial costs are a component of research and development expenses. The Company accrues and expenses clinical trial activities performed by third parties based upon actual work completed in accordance with agreements established with clinical research organizations and clinical sites. The Company determines the actual costs through discussions with internal personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services.
	Contract Manufacturing Accruals
	Contract Manufacturing costs are a component of research and development expenses. The Company accrues and expenses contract manufacturing activities performed by third parties based upon actual or the estimated amount of work completed in accordance with agreements established with contract manufacturing organizations. The Company determines the actual costs or it estimates the costs through discussions with internal personnel and external service providers as to the manufacturing activities that were performed or completed and the agreed-upon fee to be paid for such services.
	Stock-Based Compensation
	The Company accounts for stock-based compensation based on the fair value of the share-based awards that are ultimately expected to vest. The fair value of employee stock options granted is estimated on the date of grant using the Black-Scholes option pricing model, and is recognized in expense over the service period using the straight-line method, net of estimated forfeitures. Forfeiture estimates are adjusted to the extent that actual forfeitures differ from the prior estimates.
	The fair value of restricted stock unit awards used in our expense recognition method is based on the number of shares granted and the closing price of our common stock on the date of the grant. Such value is recognized as an expense over the service period using the straight-line method, net of estimated forfeitures.
	The Company records the expense attributed to nonemployee services paid with share-based awards based on the estimated fair value of the awards determined using the Black-Scholes option pricing model. The measurement of stock-based compensation for nonemployees is subject to periodic adjustments as the options vest, and the expense is recognized over the period during which services are received.
	Net Loss per Common Share
	Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per common share is calculated by dividing the net loss by the weighted-average number of common stock equivalents outstanding for the period using the treasury stock method.
	The following outstanding shares of common stock equivalents were excluded from the computations of diluted net loss per common share attributable to common stockholders for the periods presented as the effect of including such securities would be antidilutive (in thousands):
		June 30,
		2014		2013
	Convertible preferred stock — as converted to common stock		—		17,281
	Warrants to purchase convertible preferred stock — as converted to common stock		—		2,298
	Warrants to purchase common stock		56		—
	Options to purchase common stock		3,643		2,168
	Restricted stock units		19		—
	Common stock subject to repurchase		3		5
			3,721		21,752

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2014
Fair Value Measurements	'
	2.  Fair Value Measurements
	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value should maximize the use of observable inputs and minimize the use of unobservable inputs. There is a three-level valuation hierarchy for disclosure of fair value measurements, as follows:
	Level 1 – Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.
	Level 2 – Inputs (other than quoted market prices included in Level 1) that are either directly or indirectly observable, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instrument’s anticipated life.
	Level 3 – Unobservable inputs that are supported by little or no market activity and reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.
	A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.
	The following tables set forth the fair value of the Company’s financial instruments that were measured at fair value on a recurring basis as of June 30, 2014 and December 31, 2013 (in thousands):
		Level 1			Level 2		Level 3		Total
	30-Jun-14
	Financial assets:
	Money market funds	$	119,695		$	—	$	—	$	119,695
	Corporate bonds		—			17,544		—		17,544
	Commercial paper		—			21,898		—		21,898
	Total financial assets	$	119,695		$	39,442	$	—	$	159,137
	Liabilities:
	Contingent put option liability	$	—		$	—	$	110	$	110
	Total liabilities	$	—		$	—	$	110	$	110
		Level 1			Level 2		Level 3		Total
	31-Dec-13
	Financial assets:
	Money market funds	$	93,523		$	—	$	—	$	93,523
	Total financial assets	$	93,523		$	—	$	—	$	93,523
	As of June 30, 2014, the Company’s Level 3 liability is comprised of a contingent put option liability. The following table sets forth a summary of the changes in the estimated fair value of the Company’s contingent put option, which are measured at fair value on a recurring basis (in thousands):
	Balance as of December 31, 2013		$	—
	Contingent put option liability			110
	Balance as of June 30, 2014		$	110
	Where quoted prices are available in an active market, securities are classified as Level 1. The Company classifies money market funds as Level 1. When quoted market prices are not available for the specific security, then the Company estimates fair value by using benchmark yields, reported trades, broker/dealer quotes, and issuer spreads; these securities are classified as Level 2. The Company classifies corporate bonds, commercial paper and certificates of deposit as Level 2. In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3. The Company classified a contingent put option liability as a Level 3 liability. See Note 4 “Borrowings,” for further description. The fair value of the contingent put option liability was determined by using a risk-neutral valuation model, wherein the fair value of the underlying debt facility is estimated both with and without the presence of the default provisions, holding all other assumptions constant. The resulting difference between the two estimated fair values is the estimated fair value of the default provisions, or the contingent put option. The fair value of the underlying debt facility is estimated by calculating the expected cash flows in consideration of an estimated probability of default and expected recovery rate in default, and discounting such cash flows back to the reporting date using a risk-free rate. Changes to the estimated fair value of the contingent put option will be recorded in interest and other income (expense), net in the condensed statement of operations.
	The carrying values of the Company’s financial instruments, such as cash equivalents, other receivables, accounts payable, accrued liabilities and line of credit approximate fair value due to the short-term nature of these items.
	There were no transfers between Level 1 and Level 2 during the periods presented.

Cash_Cash_Equivalents_and_Shor

Cash, Cash Equivalents, and Short-Term Investments	6 Months Ended
	Jun. 30, 2014
Cash, Cash Equivalents, and Short-Term Investments	'
	3.  Cash, Cash Equivalents, and Short-Term Investments
	The following is a summary of cash, cash equivalents, and short-term investments (in thousands):
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	30-Jun-14
	Cash and money market funds	$	120,951	$	—	$	—		$	120,951
	Corporate bonds		17,545		—		(1	)		17,544
	Commercial paper		21,891		7		—			21,898
	Total financial assets	$	160,387	$	7	$	(1	)	$	160,393
	Reported as:
	Cash and cash equivalents								$	120,951
	Short-term investments									39,442
									$	160,393
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	31-Dec-13
	Cash and money market funds	$	94,759	$	—	$	—		$	94,759
	Total financial assets	$	94,759	$	—	$	—		$	94,759
	Reported as:
	Cash and cash equivalents								$	94,759
									$	94,759
	For the six months ended June 30, 2014 and 2013 and the year ended December 31, 2013, there were no realized gains or losses on the available-for-sale securities. All available-for-sale marketable securities held at June 30, 2014 have maturity dates less than one year. There were no available-for-sale marketable securities held by the Company at December 31, 2013.
	All of the Company’s available-for-sale marketable securities are subject to a periodic impairment review. The Company considers a marketable debt security to be impaired when its fair value is less than its carrying cost, in which case the Company would further review the investment to determine whether it is other-than-temporarily impaired. When the Company evaluates an investment for other-than-temporary impairment, the Company reviews factors such as the length of time and extent to which fair value has been below cost basis, the financial condition of the issuer and any changes thereto, intent to sell, and whether it is more likely than not the Company will be required to sell the investment before the recovery of its cost basis. If an investment is other-than-temporarily impaired, the Company writes it down through earnings to its impaired value and establishes that as a new cost basis for the investment. The Company did not identify any of its available-for-sale marketable securities as other-than-temporarily impaired in any of the periods presented. As of June 30, 2014, no investment was in a continuous unrealized loss position for more than one year, the unrealized losses were not due to change in credit risk and the Company believes that is more likely than not the investments will be held until maturity or a forecasted recovery of fair value.

Borrowings

Borrowings	6 Months Ended
	Jun. 30, 2014
Borrowings	'
	4.  Borrowings
	Capital Loan
	On May 30, 2014, the Company entered into an Amended and Restated Loan and Security Agreement (the Amended Loan Agreement) with Oxford Finance LLC and Silicon Valley Bank to amend and restate in its entirety the Loan and Security Agreement, (the Original Agreement), dated January 31, 2013. Per the terms of the Amended Loan Agreement, upon closing, the Company immediately drew $15.0 million, of which approximately $11.0 million was used to repay the outstanding debt under the Original Agreement, and approximately $0.4 million was used to satisfy the accrued portion of the final payment fee under the Original Agreement. Payments on the new $15.0 million will be interest only through April 2015, followed by 38 months of equal monthly payments of interest and principal. Upon acceptance of the company’s New Drug Application for patiromer by the U.S. Food and Drug Administration, the interest only payment period will be extended to December 2015 and the company may, at its option, draw an additional $20.0 million between July 1, 2015 and December 31, 2015. The Company will be required to make a final payment upon loan maturity of 8.5% of the amounts advanced and the unaccrued portion of the final payment fee under the Original Agreement in the amount of approximately $0.4 million. The interest rate for the first tranche is 7.40% and the interest rate on the second tranche will be equal to the greater of (i) the three month LIBOR rate plus 7.17% or (ii) 7.40%.
	On January 31, 2013, the Company issued warrants to purchase 54,437 shares of Series C-1 convertible preferred stock in connection with the Original Agreement. Upon the Company’s IPO in November 2013, the warrants to purchase convertible preferred stock were converted to warrants to purchase common stock.
	On May 30, 2014, the Company issued warrants to purchase 12,661 shares of common stock in connection with the first $15.0 million tranche under the Amended Loan Agreement. The fair value of the warrants was $0.2 million at the issuance date and was estimated using the Black-Scholes model with the following assumptions: a risk-free interest rate of 2.06%, a life of 7 years, a volatility factor of 91.67%, and no dividend yield. This amount is recorded as a debt discount, which will be amortized into interest expense over the repayment period. Interest expense was $0.4 million and $0.4 million for the three months ended June 30, 2014 and 2013 and $0.7 million and $0.6 million for the six months ended June 30, 2014 and 2013.
	Upon an event of default, Oxford Finance LLC and Silicon Valley Bank have the option to accelerate repayment of the Amended Loan Agreement, including payment of any applicable prepayment charges, which range from 1%-3% of the outstanding loan balance and accrued interest, as well as a final payment fee. This option is considered a contingent put option liability, as the holder of the loan may exercise the option in the event of default, and is considered an embedded derivative, which must be valued and separately accounted for in the Company’s financial statements. As of June 30, 2014 the estimated fair value of the contingent put option liability was $0.1 million, which was determined by using a risk-neutral valuation model, wherein the fair value of the underlying debt facility is estimated both with and without the presence of the default provisions, holding all other assumptions constant. The resulting difference between the two estimated fair values is the estimated fair value of the default provisions, or the contingent put option. The fair value of the underlying debt facility is estimated by calculating the expected cash flows in consideration of an estimated probability of default and expected recovery rate in default, and discounting such cash flows back to the reporting date using a risk-free rate. The contingent put option liability was recorded as a debt discount to the loan and is reported as part of the carrying value of the capital loan. The contingent put option liability is revalued at the end of each reporting period and any change in the fair value is recognized in interest and other income (expense), net.
	The Amended Loan Agreement includes customary operating but non-financial covenants, including limitations on the Company’s ability to incur additional indebtedness, issue dividends and transfer or encumber any collateral securing the debt, as well as a cross-default provision with regard to the Company’s equipment line of credit. As of June 30, 2014, principal of $15.0 million was outstanding under the Amended Loan Agreement, and the Company was in compliance with all required covenants.
	Line of Credit
	In May 2013, the Company entered into a $1.6 million equipment line of credit with a bank. The terms of repayment are 36 monthly payments, and the interest rate is fixed at 5.75%. The Company will be required to make a final payment of 9.25% of the amounts advanced. The outstanding balance on the credit line is secured by a first priority lien over all equipment purchased using the line of credit. In connection with the Company’s equipment line of credit, the Company issued a warrant to purchase 6,968 shares of Series C-1 convertible preferred stock. Upon the Company’s IPO in November 2013, the warrants to purchase convertible preferred stock were converted to warrants to purchase common stock.
	The fair value of the warrants of $25,000 at the issuance date was estimated using the Black-Scholes model with the following assumptions: a risk-free interest rate of 1.07%, a life of 7 years, a volatility factor of 91.6%, and no dividend yield. This amount is recorded as a debt discount, which is being amortized into interest expense over the repayment period. Interest expense was approximately $34,000  and $24,000 for the three months ended June 30, 2014 and 2013 and $71,000 and $24,000 for the six months ended June 30, 2014 and 2013.
	The equipment line of credit includes customary operating but non-financial covenants, including limitations on the Company’s ability to incur additional indebtedness, issue dividends and transfer or encumber any collateral securing the debt, as well as a cross-default provision with regard to the Company’s term loan. The Company utilized $1.3 million of the line of credit in the second quarter of 2013, and the remaining $0.3 million balance available under the line of credit expired unused on June 30, 2013. As of June 30, 2014, principal of $0.8 million was outstanding under the line of credit, and the Company was in compliance with all required covenants.

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies	'
	5.  Commitments and Contingencies
	Lanxess Corporation
	On November 27, 2012, Relypsa entered into a Memorandum of Understanding (MOU) with Lanxess Corporation (Lanxess), pursuant to which Lanxess serves as a commercial manufacturer and commercial supplier of the active pharmaceutical ingredient of patiromer. The MOU was amended on June 27, 2013 and September 30, 2013 (the Amended MOU) to include updated estimates of costs and timing of activities being conducted by the Company and Lanxess.
	On January 9, 2014, the Company entered into a Manufacturing and Supply Agreement (the Supply Agreement) with Lanxess that supersedes the Amended MOU. Under the Supply Agreement, Lanxess has agreed to manufacture and supply for commercial sale the drug substance for patiromer. The Supply Agreement terminates on December 31, 2020 unless terminated earlier. The Company may extend the Supply Agreement for an additional five years with notice. The Supply Agreement may be terminated (i) by the Company with notice if it abandons development or manufacturing of patiromer or fails to obtain FDA approval or the parties disagree regarding the feasibility or price of certain specification changes, or with notice at least 24 months in advance, which may be given after October 1, 2015, (ii) by Lanxess with notice if the Company fails to issue certain purchase orders, or with notice at least 24 months in advance, which may be given after October 1, 2015 and (iii) by either party with notice in the event of certain delays by the other party in performing its material obligations, or with notice if the parties fail to timely agree on certain price terms beginning in September 2015. Under the Supply Agreement, Lanxess is obligated to manufacture the Company’s commercial supply of patiromer, and the Company is obligated to purchase from Lanxess such products manufactured, pursuant to the terms and conditions of the Supply Agreement.
	During 2013 and 2014, the Company paid Lanxess for plant modifications that are required to support the manufacturing scale up of patiromer in anticipation of commercial launch. These payments are recorded in other assets these payments are being amortized to research and development expenses in accordance with the period over which the Company expects to derive future economic value. Lanxess will have full ownership of the purchased equipment and may manufacture other products with the modified plant when not occupied by the drug substance for patiromer.
	DSM Fine Chemicals
	On May 14, 2014, the Company entered into a Manufacturing and Supply Agreement (the DSM Supply Agreement) with DSM Fine Chemicals Austria NFG GMBH & Co. KG (DSM Fine Chemicals). Under the DSM Supply Agreement, DSM Fine Chemicals has agreed to manufacture and supply for commercial sale the active pharmaceutical ingredient (API) for patiromer.      Under the DSM Supply Agreement, the Company is obligated to make certain minimum purchases of API. The DSM Supply Agreement may be terminated (i) by the Company with notice if it abandons development or commercialization of patiromer or fails to obtain FDA approval, or with 12 months’ notice and without cause after DSM Fine Chemicals’ manufacture and release of certain quantity of API; (ii) by DSM Fine Chemicals within 24 months’ notice and without cause after its manufacture and release of a certain quantity of API; and (iii) by either party with notice for the other party’s uncured material breach, insolvency, liquidation, bankruptcy or dissolution.
	DSM Fine Chemicals has agreed to make plant modifications under the DSM Supply Agreement and will be the exclusive owner of the purchased equipment. DSM Fine Chemicals may manufacture other products with the modified plant when not occupied by the drug substance for patiromer. Under the DSM Supply Agreement, the Company has agreed to reimburse DSM Fine Chemicals up to a specified amount for plant modifications. These payments will be recorded in other assets and upon being placed into service, these payments will be amortized to research and development expenses in accordance with the period over which the Company expects to derive future economic value.
	The following are the combined future minimum payments under the terms of the Lanxess Supply Agreement and the DSM Supply Agreement as of June 30, 2014.  These amounts are estimates based on future market demand, quantity discounts, and manufacturing efficiencies (in thousands):
	2014	$	9,433
	2015		38,630
	2016		31,540
	2017		41,400
	2018		43,340
	Thereafter		91,792
	Total future minimum payments	$	256,135
	Operating Lease
	On June 26, 2014, the Company entered into a new lease (the Lease) for office and laboratory facilities in Redwood City, California that will serve as the Company’s new principal executive offices. The Company currently leases office and laboratory space located in Redwood City, California pursuant to a lease dated September 7, 2012 (the Existing Lease) that commenced on January 1, 2013.
	The Existing Lease provided the Company with a tenant improvement allowance in order for the Company to complete an office renovation and a lab build out. The Company accounted for the aggregate tenant improvement allowance received as leasehold improvement assets and as a deferred rent liability. These leasehold improvement assets were being amortized to depreciation expense over the shorter of the period from which the improvements were placed into service until the end of their useful life or until the end of the lease term.  The deferred rent liability was being amortized over the lease term as a credit to rent expense. Per the terms of the Lease, the Existing Lease will terminate 60 days after the lease commencement date of the Lease, which is estimated to be March 31, 2015. As of June 30, 2014, the $5.5 million net book value of the leasehold improvements and other assets to be abandoned upon the termination of the Existing Lease and the remaining deferred rent liability of $4.3 million will be amortized or depreciated over the estimated remaining nine months of the Existing Lease.
	The Lease commences on the later of (i) February 1, 2015 and (ii) the date the premises are ready for occupancy by the Company following Landlord’s construction of certain improvements to the premises required under the Lease.  The Existing Lease terminates 60 days after the lease commencement date, and the Company will not be obligated to pay any base rent, expenses or other fees under the Existing Lease during the 60-day period after the Lease commences. The Lease terminates 10 years after commencement and the Company has an option to extend the Lease for an additional five years upon written notice to Landlord.
	The Lease contains rent escalation provisions over the term of the Lease. In accordance with the terms of the Lease the Company provided a security deposit in the form of a $0.7 million irrevocable letter of credit that is collateralized by a $0.7 million restricted deposit at the Company’s bank. The total rent obligation will be expensed ratably over the term of the Lease.
	Future minimum operating lease payments at June 30, 2014, assuming the lease commences February 1, 2015 are as follows (in thousands):
	2015	$	2,178
	2016		3,178
	2017		3,340
	2018		3,440
	2019		3,543
	Thereafter		20,064
	Total future minimum payments	$	35,743
	The Company will be entitled to a one-time allowance of approximately $0.6 million for costs related to relocation, cabling, furniture, fixtures and equipment. The Company will also be entitled, at its election, to an additional allowance of approximately $2.2 million for certain move and tenant improvement related costs incurred by the Company prior to the second anniversary of the Lease commencement. In the event the Company elects to use all or any portion of the additional allowance, the base rent will increase.

Technology_Agreement

Technology Agreement	6 Months Ended
	Jun. 30, 2014
Technology Agreement	'
	6.  Technology Agreement
	During 2007, the Company acquired certain assets from Ilypsa, Inc. (Ilypsa), a wholly owned subsidiary of Amgen, Inc. (Amgen), consisting of certain property and equipment and intangible assets primarily relating to Ilypsa’s non-absorbed polymer therapeutics clinical development programs. In consideration for such transfer the Company issued 476,686 shares of Series A convertible preferred stock to Amgen valued at $8.2 million. This transaction was accounted for as an asset acquisition with the cost of the acquisition allocated to the individual assets acquired on a relative fair value basis.
	During November 2009, the Company purchased from Ilypsa certain rights Ilypsa had retained in one of the clinical development programs that the Company had acquired in 2007 under an amended intellectual property agreement. In consideration, the Company issued to Ilypsa 214,186 shares of Series A convertible preferred stock with a fair value of $2.0 million. This amount was recorded as in-process research and development and was recognized in expense, as the related clinical program is still in development and has no alternative future use.
	During February 2013, the Company dosed its first patient in a pivotal clinical trial that is evaluating patiromer for the treatment of hyperkalemia. Upon achieving this milestone the Company was required to make a one-time milestone payment of $12.5 million to Ilypsa (Amgen). The Company recognized a one-time charge to research and development expense of $12.5 million related to the required milestone payment. Upon a change in control transaction, an additional payment could be owed to Ilypsa (Amgen) ranging from 6.7% to 10% of the purchase price, less certain expenses, up to a total of $30.0 million. The Company has no obligation to make any further milestone payments or to pay royalties on future sales of patiromer to Ilypsa (Amgen).

Equity_Compensation_Plans_and_

Equity Compensation Plans and Stock Based Compensation	6 Months Ended
	Jun. 30, 2014
Equity Compensation Plans and Stock Based Compensation	'
	7.  Equity Compensation Plans and Stock Based Compensation
	The Company adopted the 2007 Equity Incentive Plan (the 2007 Plan) which provides for the granting of stock options to employees, directors and consultants of the Company. Options granted under the 2007 Plan may be either incentive stock options or nonqualified stock options. Incentive stock options may be granted only to Company employees. Nonqualified stock options may be granted to Company employees, outside directors and consultants. Options under the 2007 Plan may be granted for periods of up to ten years and are exercisable immediately, subject to rights of repurchase by the Company, which lapse over the period the applicable shares vest. Employee options granted by the Company generally vest over four years.
	In November 2013, the Company’s stockholders approved the 2013 Equity Incentive Plan (the 2013 Plan). The number of shares which may be issued or transferred under the 2013 Plan shall be equal to the sum of 1,276,587 shares and any of the shares available for issuance under the 2007 Plan. Options granted under the 2013 Plan may be granted for periods of up to ten years and are generally exercisable when vested. As of June 30, 2014, the Company has reserved 1,057,826 shares of common stock for issuance under the 2013 Plan. In June 2014, the Company’s board of directors approved the 2014 Employment Commencement Incentive Plan under which 1,000,000 shares were reserved.
	The following table summarizes option activity under the 2013 Plan and related information (in thousands, except per share and contractual term amounts):
		Shares			Shares Subject		Weighted-		Weighted-		Aggregate
		Available			to Outstanding		Average		Average		Intrinsic
		for			Options		Exercise Price		Remaining		Value
		Grant							Contractual
									Term
									(in years)
	Options Outstanding at December 31, 2013		1,233			3,545	$	5.63
	Options granted		(208	)		208		27.85
	Restricted stock units granted		(19	)		—		—
	Options exercised		—			-58		4.01
	Options forfeited		52			-52		10.36
	Balances at June 30, 2014		1,058			3,643	$	6.86		8.2	$	64,529
	Vested and expected to vest at June 30, 2014					3,519	$	6.75		8.2	$	62,688
	Vested at June 30, 2014					1,562	$	4.56		7.4	$	30,856
	The weighted-average grant-date estimated fair value of options granted during the three months ended June 30, 2014 was $17.22. No options were granted during the three months ended June 30, 2013. During the six months ended June 30, 2014 and 2013, the weighted-average grant-date estimated fair value of options granted was $22.13 and $3.78 per share, respectively. At June 30, 2014 and December 31, 2013, there were 3,389 and 5,125 shares of common stock outstanding, respectively, subject to the Company’s right of repurchase at prices ranging from $3.96 to $7.40 per share. At June 30, 2014 and December 31, 2013, the Company recorded $16,000 and $23,000, respectively, as liabilities associated with shares issued with repurchase rights. The aggregate intrinsic value of options outstanding and exercisable, vested and expected to vest were calculated as the difference between the exercise price of the options and the fair value of Relypsa’s common stock of $24.32 per share as of June 30, 2014.
	Stock-Based Compensation
	Stock-based compensation expense included in the Company’s statements of operations is as follows (in thousands):
		Three Months Ended June 30,					Six Months Ended June 30,
		2014			2013		2014		2013
	Research and development:
	Employees	$	269		$	141	$	494	$	285
	Nonemployee consultants		969			80		2,178		108
	General and administrative:
	Employees		813			225		1,378		447
	Nonemployee consultants		13			—		13		—
	Total stock-based compensation expense	$	2,064		$	446	$	4,063	$	840
	As of June 30, 2014, the Company had $18.3 million of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over an estimated weighted-average period of 2.72 years.
	The estimated grant date fair value of employee stock options was calculated using the Black-Scholes valuation model, based on the following assumptions:
		Three Months Ended June 30,					Six Months Ended June 30,
		2014			2013		2014		2013
	Expected volatility		87.24% - 93.10%			—		87.24% - 109%		94.70%
	Expected dividends		0%			—		0%		0%
	Expected term (in years)		5.5 - 6.25			—		5.5 - 6.25		6.25
	Risk-free rate		1.79% –1.94 %			—		1.79% –1.94 %		1.14%
	The fair value of nonemployee stock options was calculated using the Black-Scholes valuation model, based on the following assumptions:
		Three Months Ended June 30,					Six Months Ended June 30,
			2014		2013		2014		2013
	Expected volatility		103.76%			91.09.%-93.52%		103.76% -122.32%		91.10%-93.5%
	Expected dividends		0%			0%		0%		0%
	Expected term (in years)		6.9 – 9.1			8.1 - 9.2		6.1 – 9.3		8.1-9.5
	Risk-free rate		1.97% – 2.36 %			1.28%-2.35%		1.96% – 2.59%		1.28%-2.35%
	Restricted Stock Units
	The Company began granting restricted stock unit awards subject to performance vesting criteria to employees starting in 2014 from the 2013 Plan. Restricted stock unit awards consist of the right to receive shares of common stock, subject to achievement of time-based criteria and certain corporate performance-related goals over a specified period. The fair value of restricted stock unit awards is measured based on the number of shares granted and the closing market price of our common stock on the date of grant.
	The following table summarizes restricted stock unit activity for the six months ended June 30, 2014 (in thousands, except per share amounts):
		Restricted Stock Units
		Number of Shares			Weighted Average
					Grant Date Fair
					Value Per Share
	Nonvested at December 31, 2013		—		$	—
	Granted		19			26.23
	Vested		—			—
	Canceled		—			—
	Nonvested at June 30, 2014		19		$	26.23
	As of June 30, 2014, none of the restricted stock units granted by the Company have vested.

Description_of_Business_and_Si1

Description of Business and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2014
Organization	'
	Organization
	Relypsa, Inc. (Relypsa or the Company) is a biopharmaceutical company dedicated to the development and commercialization of new non-absorbed polymeric drugs for important applications in renal, cardiovascular and metabolic disease. The Company commenced operations on October 29, 2007. The Company’s principal operations are based in Redwood City, California and it operates in one segment.
	The information included in this quarterly report on Form 10-Q should be read in conjunction with the financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 filed with the U.S. Securities Exchange Commission (SEC).
	On April 16, 2014, the Company completed an underwritten public offering of 4,130,611 shares of common stock at an offering price of $24.50 per share. The Company received aggregate net proceeds of $94.6 million, after deducting the underwriting discounts and offering related transaction costs.
Basis of Presentation	'
	Basis of Presentation
	There have been no material changes to the Company’s significant accounting policies during the six months ended June 30, 2014 as compared to the significant accounting policies described in the Company’s audited financial statements included in the Company’s Annual Report on Form 10-K filed with the SEC for the year ended December 31, 2013.
	The accompanying financial information for the three and six months ended June 30, 2014 is unaudited. These unaudited interim condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP and applicable rules and regulations of the SEC regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. In management’s opinion, the unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013, and include all adjustments, which include only normal recurring adjustments necessary for the fair presentation of our statement of financial position as of June 30, 2014, our statements of operations and comprehensive loss for the three and six months ended June 30, 2014 and our statements of cash flows for the six months ended June 30, 2014. The results for the three and six months ended June 30, 2014 are not necessarily indicative of the results expected for the full fiscal year or any other period(s).
Use of Estimates	'
	Use of Estimates
	The preparation of these unaudited interim condensed financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of assets and liabilities, income taxes, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	On June 10, 2014, FASB issued Accounting Standards Update No. 2014-10, Development Stage Entities: Elimination of Certain Financial Reporting Requirements. The update removes the definition of a development stage entity from FASB ASC 915 and eliminates the requirement for development stage entities to present inception-to-date information on the statements of operations, cash flows and stockholders’ deficit. The Company early adopted this standard for the period covered by the report herein.
Liquidity	'
	Liquidity
	In the course of its development activities, the Company has sustained significant operating losses and expects such losses to continue over the next few years. The Company’s success depends on the outcome of its research and development activities. From inception through June 30, 2014, the Company has incurred cumulative net losses of $248.9 million. Management expects to incur additional losses in the future to conduct product research and development and commercialization activities. Additional funding will be needed to support the planned commercial launch in the United States and as the Company builds out its sales capabilities. The Company intends to raise such funding through the issuance of additional equity, debt financings or other sources, such as strategic collaborations. However, if such financing is not available at adequate levels or on acceptable terms, the Company could be required to significantly reduce operating expenses and delay, reduce the scope of or eliminate some of its development programs or its commercialization efforts, enter into a collaboration or other similar arrangement with respect to commercialization rights to patiromer or any of its other product candidates, out-license intellectual property rights to patiromer or its other product candidates and sell unsecured assets, or a combination of the above, which may have a material adverse effect on the Company’s business, results of operations, financial condition and/or its ability to fund its scheduled obligations on a timely basis or at all.
Cash Equivalents	'
	Cash Equivalents
	The Company considers all highly liquid investments purchased with original maturities of 90 days or less at the date of purchase to be cash equivalents.
Short-Term Investments	'
	Short-Term Investments
	Short-term investments consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of acquisition. Short-term investments are carried at fair value based upon quoted market prices or pricing models for similar securities. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of accumulated comprehensive income (loss). Realized gains or losses on the sale of all such securities are reported in interest and other income (expense), net and computed using the specific identification method.
Restricted Cash	'
	Restricted Cash
	Restricted cash related to the Company’s leases consists of irrevocable letters of credit that are collateralized by a restricted deposits held at the Company’s bank over a term that is consistent with the corresponding lease.
Research and Development Expenses	'
	Research and Development Expenses
	Research and development costs are charged to expense as incurred and consist of costs incurred to further the Company’s research and development activities including salaries and related employee benefits, costs associated with clinical trials, nonclinical research and development activities, regulatory activities, research-related overhead expenses and fees paid to external service providers and contract research and manufacturing organizations that conduct certain research and development activities on behalf of the Company.
Clinical Trial Accruals	'
	Clinical Trial Accruals
	Clinical trial costs are a component of research and development expenses. The Company accrues and expenses clinical trial activities performed by third parties based upon actual work completed in accordance with agreements established with clinical research organizations and clinical sites. The Company determines the actual costs through discussions with internal personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services.
Contract Manufacturing Accruals	'
	Contract Manufacturing Accruals
	Contract Manufacturing costs are a component of research and development expenses. The Company accrues and expenses contract manufacturing activities performed by third parties based upon actual or the estimated amount of work completed in accordance with agreements established with contract manufacturing organizations. The Company determines the actual costs or it estimates the costs through discussions with internal personnel and external service providers as to the manufacturing activities that were performed or completed and the agreed-upon fee to be paid for such services.
Stock-Based Compensation	'
	Stock-Based Compensation
	The Company accounts for stock-based compensation based on the fair value of the share-based awards that are ultimately expected to vest. The fair value of employee stock options granted is estimated on the date of grant using the Black-Scholes option pricing model, and is recognized in expense over the service period using the straight-line method, net of estimated forfeitures. Forfeiture estimates are adjusted to the extent that actual forfeitures differ from the prior estimates.
	The fair value of restricted stock unit awards used in our expense recognition method is based on the number of shares granted and the closing price of our common stock on the date of the grant. Such value is recognized as an expense over the service period using the straight-line method, net of estimated forfeitures.
	The Company records the expense attributed to nonemployee services paid with share-based awards based on the estimated fair value of the awards determined using the Black-Scholes option pricing model. The measurement of stock-based compensation for nonemployees is subject to periodic adjustments as the options vest, and the expense is recognized over the period during which services are received.
Net Loss per Common Share Attributable to Common Stockholders	'
	Net Loss per Common Share
	Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per common share is calculated by dividing the net loss by the weighted-average number of common stock equivalents outstanding for the period using the treasury stock method.
	The following outstanding shares of common stock equivalents were excluded from the computations of diluted net loss per common share attributable to common stockholders for the periods presented as the effect of including such securities would be antidilutive (in thousands):
		June 30,
		2014		2013
	Convertible preferred stock — as converted to common stock		—		17,281
	Warrants to purchase convertible preferred stock — as converted to common stock		—		2,298
	Warrants to purchase common stock		56		—
	Options to purchase common stock		3,643		2,168
	Restricted stock units		19		—
	Common stock subject to repurchase		3		5
			3,721		21,752

Description_of_Business_and_Si2

Description of Business and Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2014
Schedule of Shares Excluded from Computations of Diluted Net Loss per Common Share	'
	The following outstanding shares of common stock equivalents were excluded from the computations of diluted net loss per common share attributable to common stockholders for the periods presented as the effect of including such securities would be antidilutive (in thousands):
		June 30,
		2014		2013
	Convertible preferred stock — as converted to common stock		—		17,281
	Warrants to purchase convertible preferred stock — as converted to common stock		—		2,298
	Warrants to purchase common stock		56		—
	Options to purchase common stock		3,643		2,168
	Restricted stock units		19		—
	Common stock subject to repurchase		3		5
			3,721		21,752

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2014
Fair Value of Financial Instruments Measured at Fair Value on Recurring Basis	'
	The following tables set forth the fair value of the Company’s financial instruments that were measured at fair value on a recurring basis as of June 30, 2014 and December 31, 2013 (in thousands):
		Level 1			Level 2		Level 3		Total
	30-Jun-14
	Financial assets:
	Money market funds	$	119,695		$	—	$	—	$	119,695
	Corporate bonds		—			17,544		—		17,544
	Commercial paper		—			21,898		—		21,898
	Total financial assets	$	119,695		$	39,442	$	—	$	159,137
	Liabilities:
	Contingent put option liability	$	—		$	—	$	110	$	110
	Total liabilities	$	—		$	—	$	110	$	110
		Level 1			Level 2		Level 3		Total
	31-Dec-13
	Financial assets:
	Money market funds	$	93,523		$	—	$	—	$	93,523
	Total financial assets	$	93,523		$	—	$	—	$	93,523
Fair Value Contingent Liability Measured on Recurring Basis	'
	As of June 30, 2014, the Company’s Level 3 liability is comprised of a contingent put option liability. The following table sets forth a summary of the changes in the estimated fair value of the Company’s contingent put option, which are measured at fair value on a recurring basis (in thousands):
	Balance as of December 31, 2013		$	—
	Contingent put option liability			110
	Balance as of June 30, 2014		$	110

Cash_Cash_Equivalents_and_Shor1

Cash, Cash Equivalents, and Short-Term Investments (Tables)	6 Months Ended
	Jun. 30, 2014
Summary of Cash, Cash Equivalents, and Short-Term Investments	'
	The following is a summary of cash, cash equivalents, and short-term investments (in thousands):
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	30-Jun-14
	Cash and money market funds	$	120,951	$	—	$	—		$	120,951
	Corporate bonds		17,545		—		(1	)		17,544
	Commercial paper		21,891		7		—			21,898
	Total financial assets	$	160,387	$	7	$	(1	)	$	160,393
	Reported as:
	Cash and cash equivalents								$	120,951
	Short-term investments									39,442
									$	160,393
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	31-Dec-13
	Cash and money market funds	$	94,759	$	—	$	—		$	94,759
	Total financial assets	$	94,759	$	—	$	—		$	94,759
	Reported as:
	Cash and cash equivalents								$	94,759
									$	94,759

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2014
Schedule of Future Minimum Payments Under Supply Agreement	'
	The following are the combined future minimum payments under the terms of the Lanxess Supply Agreement and the DSM Supply Agreement as of June 30, 2014.  These amounts are estimates based on future market demand, quantity discounts, and manufacturing efficiencies (in thousands):
	2014	$	9,433
	2015		38,630
	2016		31,540
	2017		41,400
	2018		43,340
	Thereafter		91,792
	Total future minimum payments	$	256,135
Schedule of Future Minimum Payments Under Operating Lease	'
	Future minimum operating lease payments at June 30, 2014, assuming the lease commences February 1, 2015 are as follows (in thousands):
	2015	$	2,178
	2016		3,178
	2017		3,340
	2018		3,440
	2019		3,543
	Thereafter		20,064
	Total future minimum payments	$	35,743

Equity_Compensation_Plans_and_1

Equity Compensation Plans and Stock Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2014
Summary of Option Activity	'
	The following table summarizes option activity under the 2013 Plan and related information (in thousands, except per share and contractual term amounts):
		Shares			Shares Subject		Weighted-		Weighted-		Aggregate
		Available			to Outstanding		Average		Average		Intrinsic
		for			Options		Exercise Price		Remaining		Value
		Grant							Contractual
									Term
									(in years)
	Options Outstanding at December 31, 2013		1,233			3,545	$	5.63
	Options granted		(208	)		208		27.85
	Restricted stock units granted		(19	)		—		—
	Options exercised		—			-58		4.01
	Options forfeited		52			-52		10.36
	Balances at June 30, 2014		1,058			3,643	$	6.86		8.2	$	64,529
	Vested and expected to vest at June 30, 2014					3,519	$	6.75		8.2	$	62,688
	Vested at June 30, 2014					1,562	$	4.56		7.4	$	30,856
Schedule of Stock-Based Compensation Expense	'
	Stock-based compensation expense included in the Company’s statements of operations is as follows (in thousands):
		Three Months Ended June 30,					Six Months Ended June 30,
		2014			2013		2014		2013
	Research and development:
	Employees	$	269		$	141	$	494	$	285
	Nonemployee consultants		969			80		2,178		108
	General and administrative:
	Employees		813			225		1,378		447
	Nonemployee consultants		13			—		13		—
	Total stock-based compensation expense	$	2,064		$	446	$	4,063	$	840
Summary of Restricted Stock Unit Activity	'
	The following table summarizes restricted stock unit activity for the six months ended June 30, 2014 (in thousands, except per share amounts):
		Restricted Stock Units
		Number of Shares			Weighted Average
					Grant Date Fair
					Value Per Share
	Nonvested at December 31, 2013		—		$	—
	Granted		19			26.23
	Vested		—			—
	Canceled		—			—
	Nonvested at June 30, 2014		19		$	26.23
Employee Stock Option	'
Schedule of Valuation Assumptions Used to Calculate Fair Value of Stock Options	'
	The estimated grant date fair value of employee stock options was calculated using the Black-Scholes valuation model, based on the following assumptions:
		Three Months Ended June 30,					Six Months Ended June 30,
		2014			2013		2014		2013
	Expected volatility		87.24% - 93.10%			—		87.24% - 109%		94.70%
	Expected dividends		0%			—		0%		0%
	Expected term (in years)		5.5 - 6.25			—		5.5 - 6.25		6.25
	Risk-free rate		1.79% –1.94 %			—		1.79% –1.94 %		1.14%
Non Employee Stock Option	'
Schedule of Valuation Assumptions Used to Calculate Fair Value of Stock Options	'
	The fair value of nonemployee stock options was calculated using the Black-Scholes valuation model, based on the following assumptions:
		Three Months Ended June 30,					Six Months Ended June 30,
			2014		2013		2014		2013
	Expected volatility		103.76%			91.09.%-93.52%		103.76% -122.32%		91.10%-93.5%
	Expected dividends		0%			0%		0%		0%
	Expected term (in years)		6.9 – 9.1			8.1 - 9.2		6.1 – 9.3		8.1-9.5
	Risk-free rate		1.97% – 2.36 %			1.28%-2.35%		1.96% – 2.59%		1.28%-2.35%

Description_of_Business_and_Si3

Description of Business and Significant Accounting Policies - Additional Information (Details) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended		80 Months Ended
In Thousands, except Share data, unless otherwise specified	Apr. 16, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014
				Segment
Description Of Business And Significant Accounting Policies [Line Items]	'	'	'	'	'	'
Number of business segments	'	'	'	1	'	'
Issuance of common stock, shares	4,130,611	'	'	'	'	'
Shares issued, price per share	$24.50	'	'	'	'	'
Aggregate net proceeds from issuance of common stock	$94,600	'	'	$94,607	'	'
Cumulative net losses	'	$16,737	$20,220	$32,805	$46,471	$248,900

Description_of_Business_and_Si4

Description of Business and Significant Accounting Policies - Schedule of Shares Excluded from Computations of Diluted Net Loss per Common Share (Details)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computations of diluted net loss per common share	3,721	21,752
Convertible Preferred Stock - As Converted to Common Stock	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computations of diluted net loss per common share	'	17,281
Warrants to Purchase Convertible Preferred Stock - As Converted to Common Stock	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computations of diluted net loss per common share	'	2,298
Warrants To Purchase Common Stock	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computations of diluted net loss per common share	56	'
Options to Purchase Common Stock	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computations of diluted net loss per common share	3,643	2,168
Restricted Stock Units	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computations of diluted net loss per common share	19	'
Common Stock Subject to Repurchase	'	'
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]	'	'
Common stock equivalents excluded from computations of diluted net loss per common share	3	5

Fair_Value_Measurements_Fair_V

Fair Value Measurements - Fair Value of Financial Instruments Measured at Fair Value on Recurring Basis (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial assets:	'	'
Total financial assets	$159,137	$93,523
Liabilities:	'	'
Total liabilities	110	'
Contingent Put Option Liability	'	'
Liabilities:	'	'
Total liabilities	110	'
Level 1	'	'
Financial assets:	'	'
Total financial assets	119,695	93,523
Level 2	'	'
Financial assets:	'	'
Total financial assets	39,442	'
Level 3	'	'
Liabilities:	'	'
Total liabilities	110	'
Level 3 | Contingent Put Option Liability	'	'
Liabilities:	'	'
Total liabilities	110	'
Corporate Bonds	'	'
Financial assets:	'	'
Total financial assets	17,544	'
Corporate Bonds | Level 2	'	'
Financial assets:	'	'
Total financial assets	17,544	'
Money Market Funds	'	'
Financial assets:	'	'
Total financial assets	119,695	93,523
Money Market Funds | Level 1	'	'
Financial assets:	'	'
Total financial assets	119,695	93,523
Commercial Paper	'	'
Financial assets:	'	'
Total financial assets	21,898	'
Commercial Paper | Level 2	'	'
Financial assets:	'	'
Total financial assets	$21,898	'

Fair_Value_Measurements_Contin

Fair Value Measurements - Contingent Put Option Measured at Fair Value on Recurring Basis (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Contingent liability	$110	'
Contingent Put Option Liability	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Contingent liability	110	'
Level 3	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Contingent liability	110	'
Level 3 | Contingent Put Option Liability	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Contingent liability	110	'
Estimated Fair Value | Level 3	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Contingent liability	110	'
Estimated Fair Value | Level 3 | Contingent Put Option Liability	'	'
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]	'	'
Contingent liability	$110	'

Cash_Cash_Equivalents_and_Shor2

Cash, Cash Equivalents, and Short-Term Investments - Summary of Cash, Cash Equivalents, and Short-Term Investments (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Cash And Cash Equivalents [Line Items]	'	'	'	'
Amortized Cost	$160,387	$94,759	'	'
Gross Unrealized Gains	7	'	'	'
Gross Unrealized Losses	-1	'	'	'
Estimated Fair Value	160,393	94,759	'	'
Cash and cash equivalents	120,951	94,759	14,102	15,221
Short-term investments	39,442	'	'	'
Total financial assets	160,393	94,759	'	'
Cash and Money Market Funds	'	'	'	'
Cash And Cash Equivalents [Line Items]	'	'	'	'
Amortized Cost	120,951	94,759	'	'
Gross Unrealized Gains	'	'	'	'
Gross Unrealized Losses	'	'	'	'
Estimated Fair Value	120,951	94,759	'	'
Commercial Paper	'	'	'	'
Cash And Cash Equivalents [Line Items]	'	'	'	'
Amortized Cost	21,891	'	'	'
Gross Unrealized Gains	7	'	'	'
Estimated Fair Value	21,898	'	'	'
Corporate Bonds	'	'	'	'
Cash And Cash Equivalents [Line Items]	'	'	'	'
Amortized Cost	17,545	'	'	'
Gross Unrealized Losses	-1	'	'	'
Estimated Fair Value	$17,544	'	'	'

Cash_Cash_Equivalents_and_Shor3

Cash, Cash Equivalents, and Short-Term Investments - Additional Information (Details) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Cash And Cash Equivalents [Line Items]	'	'	'
Realized gain or losses on available-for-sale securities	$0	$0	$0
Maximum	'	'	'
Cash And Cash Equivalents [Line Items]	'	'	'
Available-for-sale marketable securities maturity dates	'1 year	'	'

Borrowings_Additional_Informat

Borrowings - Additional Information (Details) (USD $)

6 Months Ended

3 Months Ended

6 Months Ended

0 Months Ended

3 Months Ended

6 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

31-May-13

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

31-May-13

30-May-14

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2014

Jan. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Line of Credit

Line of Credit

Line of Credit

Line of Credit

Series C-1 Convertible Preferred Stock

Capital Loan

Capital Loan

Capital Loan

Capital Loan

Capital Loan

Capital Loan

Capital Loan

Capital Loan

Capital Loan

Capital Loan

Payment

Payment

Line of Credit

Payment

Payment

Minimum

Maximum

Series C-1 Convertible Preferred Stock

Initial advance

Second Tranche

Three Month LIBOR Rate

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from advance

$3,549,000

$12,404,000

'

'

'

'

'

'

$15,000,000

'

'

'

'

'

'

'

'

'

Repayment of outstanding debt

'

'

'

'

'

'

'

'

'

'

'

11,000,000

'

'

'

'

'

'

Final payment fee

'

'

'

'

'

'

'

'

'

400,000

'

400,000

'

'

'

'

'

'

Advance not yet received

'

'

'

'

'

'

'

'

'

20,000,000

'

20,000,000

'

'

'

'

'

'

Debt instrument, payment terms

'

'

'

'

'

'

'

'

'

'

'

'Payments on the new $15.0 million will be interest only through April 2015, followed by 38 months of equal monthly payments of interest and principal.

'

'

'

'

'

'

Number of debt repayments

'

'

'

36

'

36

'

'

'

38

'

38

'

'

'

'

'

'

Final payment as a percentage of amounts borrowed

'

'

'

'

'

9.25%

'

'

'

'

'

8.50%

'

'

'

'

'

'

Debt instrument, interest rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7.40%

'

Debt instrument, basis spread on variable rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7.17%

Warrants issued to purchase preferred stock

'

'

'

'

'

'

'

6,968

'

'

'

'

'

'

'

54,437

'

'

Warrant issued to purchase common stock

'

'

'

'

'

'

'

'

12,661

'

'

'

'

'

'

'

'

'

Fair value of warrants

'

'

'

25,000

'

25,000

'

'

'

200,000

'

200,000

'

'

'

'

'

'

Warrants, fair value assumptions, interest rate

'

'

'

'

'

1.07%

'

'

'

'

'

2.06%

'

'

'

'

'

'

Warrants, fair value assumptions, expected life

'

'

'

'

'

'7 years

'

'

'

'

'

'7 years

'

'

'

'

'

'

Warrants, fair value assumptions, volatility factor

'

'

'

'

'

91.60%

'

'

'

'

'

91.67%

'

'

'

'

'

'

Warrants, fair value assumptions, dividend yield

'

'

'

'

'

0.00%

'

'

'

'

'

0.00%

'

'

'

'

'

'

Interest expense

'

'

'

34,000

24,000

71,000

24,000

'

'

400,000

400,000

700,000

600,000

'

'

'

'

'

Prepayment charges of outstanding loan

'

'

'

'

'

'

'

'

'

'

'

'

'

1.00%

3.00%

'

'

'

Estimated fair value of contingent put option liability

'

'

'

'

'

'

'

'

'

100,000

'

100,000

'

'

'

'

'

'

Principal amount outstanding on loan

'

'

'

'

'

'

'

'

'

15,000,000

'

15,000,000

'

'

'

'

'

'

Line of credit amount

'

'

1,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit, terms of repayment

'The terms of repayment are 36 monthly payments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit, interest rate

5.75%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit, utilized amount

'

'

'

'

1,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit, remaining and expired amount

'

300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit, expiry date

30-Jun-13

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit principal amount outstanding

$800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Details) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014
Loss Contingencies [Line Items]	'
MOU first amendment date	27-Jun-13
MOU second amendment date	30-Sep-13
Supply agreement term	'The Supply Agreement terminates on December 31, 2020 unless terminated earlier. The Company may extend the Supply Agreement for an additional five years with notice.
Agreement termination date	31-Dec-20
Extended agreement period	'5 years
Additional lease allowance	$2.20
One-time lease improvement allowance	0.6
Lease commencement date	1-Feb-15
Lease termination period	'60 days
Operating lease, term of contract	'10 years
Operating lease, renewal term	'5 years
Irrevocable Letter of Credit	'
Loss Contingencies [Line Items]	'
Security deposit	$0.70
DSM Fine Chemicals	'
Loss Contingencies [Line Items]	'
Supply agreement term	'The Agreement terminates on May 14, 2021 unless earlier terminated.
Agreement termination date	14-May-21

Commitments_and_Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Payments Under Supply Agreement(Details) (DSM Fine Chemicals and Lanxess, USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
DSM Fine Chemicals and Lanxess	'
Long Term Purchase Commitment [Line Items]	'
2014	$9,433
2015	38,630
2016	31,540
2017	41,400
2018	43,340
Thereafter	91,792
Total future minimum payments	$256,135

Commitments_and_Contingencies_3

Commitments and Contingencies - Schedule of Future Minimum Payments Under Operating Lease (Details) (USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Operating Leased Assets [Line Items]	'
2015	$2,178
2016	3,178
2017	3,340
2018	3,440
2019	3,543
Thereafter	20,064
Total future minimum payments	$35,743

Technology_Agreement_Additiona

Technology Agreement - Additional Information (Details) (USD $)	1 Months Ended			12 Months Ended	1 Months Ended
In Millions, except Share data, unless otherwise specified	Feb. 28, 2013	Feb. 28, 2013	Feb. 28, 2013	Dec. 31, 2007	Nov. 30, 2009
		Minimum	Maximum	Series A Convertible Preferred Stock	Series A Convertible Preferred Stock
					Intellectual Property Rights
Finite Lived Intangible Assets [Line Items]	'	'	'	'	'
Shares issued during period for assets acquired	'	'	'	476,686	214,186
Shares issued during period for assets acquired, value	'	'	'	$8.20	$2
Research and development expense	12.5	'	'	'	'
Transaction cost, additional payment percentage on purchase price	'	6.70%	10.00%	'	'
Acquisition expenses	$30	'	'	'	'

Equity_Compensation_Plans_and_2

Equity Compensation Plans and Stock Based Compensation - Additional Information (Details) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended			0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Nov. 30, 2013	Jun. 30, 2014	Jun. 30, 2014
						Minimum	Maximum	2007 Equity Incentive Plan	2013 Equity Incentive Plan	2013 Equity Incentive Plan	2014 Employment Commencement Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Option granted period	'	'	'	'	'	'	'	'10 years	'10 years	'	'
Option vest over period	'	'	'	'	'	'	'	'4 years	'	'	'
Share issued or transferred under the Plan	'	'	'	'	'	'	'	'	1,276,587	'	'
Common stock reserved for issuance	'	'	'	'	'	'	'	'	'	1,057,826	1,000,000
Weighted-average grant-date fair value of options grant	$17.22	'	$22.13	$3.78	'	'	'	'	'	'	'
Common stock outstanding, right of repurchase shares	3,389	'	3,389	'	5,125	'	'	'	'	'	'
Repurchase price per share	'	'	'	'	'	$3.96	$7.40	'	'	'	'
Per share price of aggregate intrinsic value of options	$24.32	'	$24.32	'	'	'	'	'	'	'	'
Liabilities associated with shares issued with repurchase rights	$16,000	'	$16,000	'	$23,000	'	'	'	'	'	'
Shares Available for Grant, Options granted	'	0	208,000	'	'	'	'	'	'	'	'
Unrecognized compensation cost	$18,300,000	'	$18,300,000	'	'	'	'	'	'	'	'
Expected period of compensation expense recognized	'	'	'2 years 8 months 19 days	'	'	'	'	'	'	'	'

Equity_Compensation_Plans_and_3

Equity Compensation Plans and Stock Based Compensation - Summary of Option Activity (Details) (USD $)	3 Months Ended	6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'
Shares Available for Grant, Options Outstanding, beginning balance	'	1,233
Shares Available for Grant, Options granted	0	-208
Shares Available for Grant, Restricted stock units granted	'	-19
Shares Available for Grant, Options forfeited	'	52
Shares Available for Grant, Options Outstanding, ending balance	'	1,058
Shares Subject to Outstanding Options, Options Outstanding, beginning balance	'	3,545
Shares Subject to Outstanding Options, Options granted	'	208
Shares Subject to Outstanding Options, Options exercised	'	-58
Shares subject to Outstanding Options, Options forfeited	'	-52
Shares Subject to Outstanding Options, Options Outstanding, ending balance	'	3,643
Shares Subject to Outstanding Options, Vested and expected to vest	'	3,519
Shares Subject to Outstanding Options, Vested	'	1,562
Weighted-Average Exercise Price, Options Outstanding, beginning balance	'	$5.63
Weighted-Average Exercise Price, Options granted	'	$27.85
Weighted-Average Exercise Price, Options exercised	'	$4.01
Weighted-Average Exercise Price, Options forfeited	'	$10.36
Weighted-Average Exercise Price, Options Outstanding, ending balance	'	$6.86
Weighted-Average Exercise Price, Vested and expected to vest	'	$6.75
Weighted-Average Exercise Price, Vested	'	$4.56
Weighted-Average Remaining Contractual Term, Options Outstanding	'	'8 years 2 months 12 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	'	'8 years 2 months 12 days
Weighted-Average Remaining Contractual Term, Vested	'	'7 years 4 months 24 days
Aggregate Intrinsic Value, Options Outstanding	'	$64,529
Aggregate Intrinsic Value, Vested and expected to vest	'	62,688
Aggregate intrinsic value, Vested	'	$30,856

Equity_Compensation_Plans_and_4

Equity Compensation Plans and Stock Based Compensation - Schedule of Stock-Based Compensation Expense (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Stock-based compensation	$2,064	$446	$4,063	$840
Research and Development | Employees	'	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Stock-based compensation	269	141	494	285
Research and Development | Nonemployee Consultants	'	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Stock-based compensation	969	80	2,178	108
General and Administrative | Employees	'	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Stock-based compensation	813	225	1,378	447
General and Administrative | Nonemployee Consultants	'	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Stock-based compensation	$13	'	$13	'

Equity_Compensation_Plans_and_5

Equity Compensation Plans and Stock Based Compensation - Schedule of Valuation Assumptions Used to Calculate Fair Value of Employee Stock Options (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'
Expected volatility	'	'	94.70%
Expected dividends	0.00%	0.00%	0.00%
Expected term (in years)	'	'	'6 years 3 months
Risk-free rate	'	'	1.14%
Risk-free rate, minimum	1.79%	1.79%	'
Risk-free rate, maximum	1.94%	1.94%	'
Minimum	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'
Expected volatility	87.24%	87.24%	'
Expected term (in years)	'5 years 6 months	'5 years 6 months	'
Maximum	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'
Expected volatility	93.10%	109.00%	'
Expected term (in years)	'6 years 3 months	'6 years 3 months	'

Equity_Compensation_Plans_and_6

Equity Compensation Plans and Stock Based Compensation - Schedule of Valuation Assumptions Used to Calculate Fair Value of Nonemployee Stock Options (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Expected volatility	103.76%	'	'	'
Expected dividends	0.00%	0.00%	0.00%	0.00%
Expected term (in years)	'	'	'	'
Risk-free rate	'	1.14%	'	'
Minimum	'	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Expected volatility	'	91.09%	103.76%	91.10%
Expected term (in years)	'6 years 10 months 24 days	'8 years 1 month 6 days	'6 years 1 month 6 days	'8 years 1 month 6 days
Risk-free rate	1.97%	1.28%	1.96%	1.28%
Maximum	'	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'	'	'	'
Expected volatility	'	93.52%	122.32%	93.50%
Expected term (in years)	'9 years 1 month 6 days	'9 years 2 months 12 days	'9 years 3 months 18 days	'9 years 6 months
Risk-free rate	2.36%	2.35%	2.59%	2.35%

Equity_Compensation_Plans_and_7

Equity Compensation Plans and Stock Based Compensation - Summary of Restricted Stock Unit Activity (Details) (USD $)	6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]	'
Number of Shares, Nonvested at Beginning	'
Number of Shares, Granted	19
Number of Shares, Vested	'
Number of Shares, Canceled	'
Number of Shares, Nonvested at Ending	19
Weighted Average Grant Date Fair Value Per Share, Nonvested at Beginning	'
Weighted Average Grant Date Fair Value Per Share, Granted	$26.23
Weighted Average Grant Date Fair Value Per Share, Vested	'
Weighted Average Grant Date Fair Value Per Share, Canceled	'
Weighted Average Grant Date Fair Value Per Share, Nonvested at Ending	$26.23