ZS Pharma (ZSPH) 10-Q 14 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Aug. 14, 2014
Document And Entity Information [Abstract]	'	'
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	'ZSPH	'
Entity Registrant Name	'ZS Pharma, Inc.	'
Entity Central Index Key	'0001459266	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	20,818,771

Condensed_Balance_Sheets

Condensed Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$130,002	$9,170
Restricted cash	150	150
Other current assets	610	77
Total current assets	130,762	9,397
Property and equipment, net	9,950	4,625
Other assets	25	24
Total assets	140,737	14,046
Current liabilities:	'	'
Accounts payable	6,779	1,489
Accrued liabilities	4,173	3,114
Current portion of capital lease obligation	304	73
Total current liabilities	11,256	4,676
Deferred rent	71	67
Lease incentive	138	184
Capital lease obligation	279	'
Total liabilities	11,744	7,594
Commitments and contingencies	'	'
Shareholders' equity (deficit):	'	'
Convertible preferred stock	0	0
Common stock, par $0.001; 250,000,000 and 49,574,865 shares authorized at June 30, 2014 and December 31, 2013, respectively; 20,818,771 and 1,628,976 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively	21	2
Additional paid-in capital	206,072	3,854
Accumulated deficit	-77,100	-50,234
Total shareholders' equity (deficit)	128,993	-45,182
Total liabilities and shareholders' equity (deficit)	140,737	14,046
Series B Preferred Stock [Member]	'	'
Current liabilities:	'	'
Series B redeemable preferred stock warrant liability	'	2,667
Shareholders' equity (deficit):	'	'
Convertible preferred stock	0	8,387
Series C Preferred Stock [Member]	'	'
Shareholders' equity (deficit):	'	'
Convertible preferred stock	0	43,247
Series A Preferred Stock [Member]	'	'
Shareholders' equity (deficit):	'	'
Convertible preferred stock	$0	$1,196

Condensed_Balance_Sheets_Paren

Condensed Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	5,000,000	0
Convertible preferred stock, shares issued	0	0
Convertible preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	250,000,000	49,574,865
Common stock, shares issued	20,818,771	1,628,976
Common stock, shares outstanding	20,818,771	1,628,976
Series B Preferred Stock [Member]	'	'
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	'	6,768,033
Convertible preferred stock, shares issued	'	2,261,488
Convertible preferred stock, shares outstanding	'	2,261,488
Convertible preferred stock, liquidation value	'	$8,409
Series C Preferred Stock [Member]	'	'
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	'	17,692,308
Convertible preferred stock, shares issued	'	6,899,275
Convertible preferred stock, shares outstanding	'	6,899,275
Convertible preferred stock, liquidation value	'	$46,000
Series A Preferred Stock [Member]	'	'
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	'	1,494,966
Convertible preferred stock, shares issued	'	582,965
Convertible preferred stock, shares outstanding	'	582,965

Condensed_Statements_of_Operat

Condensed Statements of Operations (Unaudited) (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
Costs and expenses:	'	'	'	'
Research and development	$9,976	$6,335	$15,235	$10,744
General and administrative	4,554	972	8,571	1,687
Total cost and expenses	14,530	7,307	23,806	12,431
Loss from operations	-14,530	-7,307	-23,806	-12,431
Other (income) expense:	'	'	'	'
Interest income	-10	-8	-16	-20
Interest expense	5	4	8	9
Expense to mark warrants to market	1,774	12	3,071	121
Other	'	'	-3	'
Net loss	-16,299	-7,315	-26,866	-12,541
Preferred stock accretion	-129	-172	-310	-342
Net loss attributable to common shareholders	($16,428)	($7,487)	($27,176)	($12,883)
Net loss per share attributable to common shareholders, basic and diluted	($4.72)	($4.81)	($10.61)	($8.27)
Weighted-average common shares used to compute net loss per share attributable to common shareholders, basic and diluted	3,482,340	1,557,643	2,560,778	1,557,643

Statement_of_Cash_Flows_Unaudi

Statement of Cash Flows (Unaudited) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Operating activities	'	'
Net loss	($26,866)	($12,541)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation and amortization	522	232
Amortization of lease incentive	-46	'
Share-based expenses	2,918	92
Series B warrant mark-to-market expense	3,071	121
Changes in operating assets and liabilities:	'	'
Prepaid expenses and other assets	-534	-57
Accounts payable	3,758	777
Accrued expenses	1,059	278
Deferred rent	4	24
Net cash used in operating activities	-16,114	-11,075
Investing activities	'	'
Purchases of property and equipment	-3,732	-2,163
Net cash used in investing activities	-3,732	-2,163
Financing activities	'	'
Proceeds from exercise of warrants	3,780	'
Proceeds from issuance of common stock, net of issuance costs	112,195	'
Principal payments on capital lease	-73	-70
Net cash provided by financing activities	140,678	-70
Net increase (decrease) in cash and cash equivalents	120,832	-13,308
Cash and cash equivalents at beginning of period	9,170	24,401
Cash and cash equivalents at end of period	130,002	11,093
Series D Preferred Stock [Member]	'	'
Financing activities	'	'
Proceeds from issuance of Series D preferred stock, net of issuance costs	24,776	'
Series B Warrant [Member]	'	'
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Series B warrant mark-to-market expense	$3,071	$120

Nature_of_Business_and_Summary

Nature of Business and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Nature of Business and Summary of Significant Accounting Policies	'
	1	Nature of Business and Summary of Significant Accounting Policies
	Organization
	ZS Pharma Inc. is a biopharmaceutical company focused on the development and commercialization of highly selective, non-absorbed drugs to treat renal, cardiovascular, liver and metabolic diseases. Our proprietary zirconium silicate technology allows us to create highly selective ion traps that can reduce toxic levels of specific electrolytes without disturbing the balance of other electrolytes. We are currently conducting a Phase III study with our lead product candidate, ZS9 for the treatment of hyperkalemia, a life-threatening condition in which elevated levels of potassium increase the risk of muscle dysfunction, including cardiac arrhythmias and sudden cardiac death.
	On June 17, 2014, our registration statement on Form S-1 (File No. 333-195961) relating to our initial public offering (IPO) of our common stock was declared effective by the Securities and Exchange Commission (SEC). Our shares began trading on The NASDAQ Global Select Market on June 18, 2014. The public offering price of the shares sold in the offering was $18.00 per share. The IPO closed on June 23, 2014 and included 6,836,111 shares of common stock, which included 891,667 shares of common stock issued pursuant to the option granted to the underwriters to purchase additional shares. We received total proceeds from the offering of $114.4 million, net of underwriting discounts and commissions of $8.6 million. After deducting offering expenses of approximately $2.2 million, net proceeds were approximately $112.2 million. Upon the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 11,979,479 shares of common stock.
	Upon the effectiveness of the Amended and Restated Certificate of Incorporation of the Company on June 23, 2014, the number of shares of capital stock the Company is authorized to issue was increased to 255,000,000 shares, of which 250,000,000 shares are common stock and 5,000,000 shares are preferred stock. Both the common stock and preferred stock have a par value of $0.001 per share. There were no shares of preferred stock outstanding at June 30, 2014.
	Basis of Presentation
	The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements.
	The condensed interim balance sheet as of June 30, 2014, and the interim condensed statements of operations for the three and six months ended June 30, 2014 and 2013, and the condensed statements of cash flows for the six months ended June 30, 2014 and 2013, are unaudited. The unaudited interim condensed financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly our financial position as of June 30, 2014, and our results of operations for the three and six months ended June 30, 2014 and 2013, and cash flows for the six months ended June 30, 2014 and 2013. The financial data and the other financial information disclosed in these notes to the financial statements related to the three-month periods and the six-month periods, are also unaudited. The results of operations for the three months ended June 30, 2014, are not necessarily indicative of the results to be expected for the year ending December 31, 2014, or for any other future annual or interim period. The condensed balance sheet as of December 31, 2013 included herein was derived from the audited financial statements as of that date. These financial statements should be read in conjunction with our audited financial statements included in our prospectus dated June 17, 2014, filed with the SEC pursuant to Rule 424(b)(4) of the Securities Act.
	Reverse Stock Split
	In June 2014, our board of directors and our stockholders approved an amendment to our amended and restated certificate of incorporation to effect a reverse split of shares of our common stock on a 1-for-2.56437 basis (the Reverse Stock Split). The par values and the authorized shares of the common and convertible preferred stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock, convertible preferred stock, options for common stock, warrants for common and preferred stock, and per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The Reverse Stock Split was made effective on June 11, 2014.
	Use of Estimates
	The preparation of the financial statements in accordance with U.S. GAAP requires management to make certain estimates and judgments that affect the reported amounts of assets, liabilities, and expenses. Actual results could differ from those estimates.
	We estimate our clinical trial expense accrual for a given period based on the number of patients enrolled at each site and the length of time each patient has been in the trial, less amounts previously billed, plus any ancillary clinical trial expenses that have been incurred but not yet recorded.
	We measure and recognize compensation expense for all stock options granted to our employees and directors, based on the estimated fair value of the award on the grant date. We use the Black-Scholes valuation model to estimate the fair value of stock option awards. The fair value is recognized as expense, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award on a straight-line basis. We believe that the fair value of stock options granted to non-employees is more reliably measured than the fair value of the services received. As such, the fair value of the unvested portion of the options granted to non-employees is re-measured each period. The resulting increase in value, if any, is recognized as expense during the period the related services are rendered. The determination of the grant-date fair value of options using an option-pricing model is affected by our estimated common stock fair value, as well as assumptions regarding a number of other complex and subjective variables.
	Cash and Cash Equivalents
	We consider all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. We place our cash with institutions with high credit quality. However, at certain times such cash may be in excess of Federal Deposit Insurance Corporation and Securities Investor Protection Corporation insurance limits. The carrying amount of cash approximates fair value.
	Restricted Cash
	On November 22, 2013, we executed an agreement to pledge, assign, transfer, and grant a security interest to J.P. Morgan Bank to secure the payment and performance of our credit card program. We have agreed to maintain $150,000 in a restricted cash account, given we are a pre-revenue company.
	Redeemable Preferred Stock Warrant Liability
	Freestanding warrants for shares that were either puttable or redeemable were classified as liabilities on the balance sheet and were carried at their estimated fair value. The Series B Redeemable Preferred Stock, which was able to be purchased with the warrants, was redeemable at a future date in 2017. As such, these warrants were classified as liabilities, and at the end of each reporting period, changes in the estimated fair value during the period were recorded in other income (expense). Prior to June 17, 2014, the warrants were all exercised into Series B Redeemable Preferred Stock, which was converted into Common Stock upon the IPO, and the amount of warrant liability was reclassified to shareholders’ equity.
	Fair Value Measurements
	ASC 820, Fair Value Measurement, provides a comprehensive framework for measuring the fair value of assets and liabilities, which provides for consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases require, estimates of fair market value.
	Financial assets and liabilities that have recurring fair value measurements are shown below (in thousands):
						Fair Value Measurements at
						December 31, 2013, Using
						Quoted		Significant		Significant
						Prices in		Other		Unobservable
						Active		Observable		Inputs
						Markets for		Inputs
						Identical
						Assets
	Description		Total			Level 1		Level 2		Level 3
	Financial liabilities:
	Series B Redeemable Preferred Stock warrants		$	2,667		$	—	$	—	$	2,667
	Total financial liabilities		$	2,667		$	—	$	—	$	2,667
	Level 3 liabilities comprise redeemable preferred stock warrant liabilities. These warrants were classified as liabilities because the Series B Redeemable Preferred shares that were able to be purchased by these warrants were redeemable and, therefore, are classified as temporary equity. The following table sets forth a summary of the changes in the estimated fair value of our redeemable preferred stock warrants, which were measured at fair value on a recurring basis (in thousands):
	Balance as of December 31, 2013		$	2,667
	Net increase in fair value			3,071
	Amount reclassified to shareholders’ equity upon exercise			(5,738	)
	Balance as of June 30, 2014		$	—
	The fair value of the outstanding Series B Redeemable Preferred Stock warrants was measured using the Black-Scholes option-pricing model. Inputs used to determine estimated fair value included the estimated fair value of the warrant, as determined by the fair value of the underlying stock relative to the warrant exercise price at the valuation measurement date, volatility of the price of the underlying stock, the remaining contractual term of the warrants, risk-free interest rates, and expected dividends.
	We believe the recorded values of cash and cash equivalents, other current assets, accounts payable, and accrued expenses approximate fair value because of the short maturity of these financial instruments.
	Income Taxes
	We account for income taxes using the asset and liability approach in accordance with the provision of ASC 740, Income Taxes. Under this approach, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We continue to record a valuation allowance for the full amount of deferred tax assets, which would otherwise be recorded for tax benefits relating to the operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not.
	We account for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, we recognize the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. As of June 30, 2014 and 2013, we had no uncertain tax positions and no interest or penalties have been charged us from inception through June 30, 2014. If incurred, we will classify any interest and penalties as a component of tax expense.
	In April 2014, we determined that we had a change of ownership, as defined under Internal Revenue Code Section 382 (Section 382), at the time of the closing of the first tranche of Series C Redeemable Preferred Stock in October 2012. According to the provisions of Section 382, our net operating losses and research credits will be subject to an annual limitation. We have not yet determined the amount of the annual limitations to our net operating losses or research credits.
	Comprehensive Income (Loss)
	Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions, and other events and circumstances from non-owner sources. For the three months ended June 30, 2014 and 2013 and the six months ended June 30, 2014 and 2013, net loss equaled comprehensive loss.
	Net Loss per Common Share Attributable to Common Shareholders
	Basic net loss per share attributable to common shareholders is calculated by dividing the net loss attributable to common shareholders by the weighted-average number of common shares outstanding during the period without consideration for common stock equivalents. Diluted net loss per share of common stock is the same as basic net loss per share of common stock, since the effects of potentially dilutive securities are antidilutive. The net loss per share of common stock attributable to common shareholders was computed using the two-class method required for participating securities. All series of our convertible preferred stock were considered to be participating securities as they were entitled to participate in undistributed earnings with shares of common stock. Due to our net loss, there was no impact on the earnings per share calculation in applying the two-class method since the participating securities had no legal requirement to share in any losses.
	The following outstanding shares of common stock equivalents were excluded from the computations of diluted net loss per common share attributable to common shareholders for the periods presented as the effect of including such securities would be antidilutive:
			Six Months
			Ended June 30
			2014			2013
	Convertible preferred stock – as converted to common stock			—			7,478,998
	Warrants to purchase convertible preferred stock – as converted to common stock			—			377,743
	Warrants to purchase common stock			—			445,538
	Options to purchase common stock			4,229,864			2,308,044
				4,229,864			10,610,323
	Recent Accounting Pronouncements
	In June 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-10, which eliminates the financial reporting distinction between development stage entities and other reporting entities, thereby eliminating the requirements to present inception-to-date information in the statements of operations and stockholders’ equity and cash flow, or label the financial statements as those of a development stage entity. The Company has elected to early adopt this guidance, as permitted, for its financial statements for the year ended December 31, 2014, including this quarterly report, and therefore has no longer labeled its financial statements as those of a development stage entity or included any inception-to-date information.

ShareBased_Compensation

Share-Based Compensation	6 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Share-Based Compensation	'
	2	Share-Based Compensation
	We have an employee stock option plan (the Plan), which authorizes the granting of 5,010,977 shares of Common Stock to our employees and directors, as well as non-employees, and allows the holder of the option to purchase Common Stock at a stated exercise price.
	Our stock option activity and related information are summarized as follows:
			Outstanding Options
			Number		Weighted-		Weighted-
			of Shares		Average		Average
					Exercise		Remaining
					Price		Contractual
							Life in
							Years
	Options outstanding at December 31, 2013			3,286,870	$	2.05		8.77
	Options granted			300,401		5.62		9.82
	Options exercised			—		—		—
	Options forfeited			—		—		—
	Options outstanding at March 31, 2014			3,587,271		2.36		8.63
	Options granted			642,593		15.14		9.86
	Options exercised			—		—		—
	Options forfeited			—		—		—
	Options outstanding at June 30, 2014			4,229,864	$	4.29		8.61
	Exercisable at June 30, 2014			1,058,496	$	1.86		7.42
	Included in the table above are 189,847 options granted to our chief executive officer (CEO) on January 25, 2014 that contain dual-trigger vesting provisions that require the CEO to meet both a service requirement (time vesting over four years) and the achievement of certain events at specified prices in order to fully vest in the options granted, including the closing of the Series D Redeemable Preferred Stock Financing, which occurred on February 28, 2014, and the closing of our initial public offering, or IPO, which occurred on June 23, 2014 (event based vesting). The number of options in which the CEO could potentially vest is divided into two tranches and is dependent upon the actual price per share at which a closing of the above-mentioned events occurs.
	The event based vesting requirements of the first tranche of 31,641 options were met upon the closing of the Series D Redeemable Preferred Stock Financing. The event based vesting requirements of the second tranche of up to 158,206 options were met upon the closing of our IPO. The Company utilized a Monte Carlo simulation method to estimate the fair value of these options on the grant date, and the following grant date fair values were calculated for each tranche of the award:
			Number of		Grant Date
			Options
					Fair Value
	IPO Scenario
	- Closing of Series D Preferred Stock Financing			31,641	$	144,931
	- Closing of IPO			158,206	$	538,520
				189,847	$	683,451
	We began recording expense for these awards over the remaining service period with a cumulative catch up to expense when the event based performance requirements were met (i.e. at the closing of the round of Series D Redeemable Preferred Stock and the IPO).
	We calculate the intrinsic value of our options by multiplying the number of options by the difference between the estimated fair value per share for our common stock and the options’ exercise price. The aggregate intrinsic value of options exercisable and options outstanding as of June 30, 2014, was $28.5 million and $103.4 million, respectively. We will issue new shares of Common Stock upon the exercise of vested options.
	The weighted-average grant-date fair value of options granted in the three months ended June 30, 2014 and 2013 was $12.55 and $3.51 per option, respectively, and for the six months ended June 30, 2014 and 2013 was $10.02 and $3.51 per option, respectively.
	At June 30, 2014, total compensation cost related to non-vested awards not yet recognized was $13.6 million, and the weighted-average period over which this amount is expected to be recognized was 2.99 years.

Preferred_Stock

Preferred Stock	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Preferred Stock	'
	3	Preferred Stock
	As of December 31, 2013, there were 582,965 shares of Series A Preferred Stock outstanding; 2,261,488 shares of Series B Redeemable Preferred Stock outstanding, and 6,899,275 shares of Series C Redeemable Preferred Stock outstanding. On February 28, 2014, we issued 1,858,008 shares of Series D Redeemable Preferred Stock with a par value of $0.001 and an Original Issue Price of $13.46 per share, with gross proceeds from the transaction totaling $25.0 million.
	Between May 23, 2014 and June 5, 2014, holders of 377,743 Series B warrants exercised their rights under the warrants to purchase an equal number of shares of Series B Redeemable Preferred Stock. The aggregate gross proceeds from these Series B warrant exercises was $1.4 million.
	On June 23, 2014, upon the closing of the IPO and the filing of our Seventh Amended and Restated Certificate of Incorporation, each one of the outstanding shares of Preferred Stock and Redeemable Preferred Stock was converted to a share of common stock, with a total of 11,979,479 shares converted to common stock. In addition, 5,000,000 shares of new Preferred Stock, par value $0.001 per share, were authorized. The voting powers, preferences and other rights of these Preferred Shares will be determined by our Board of Directors prior to their issuance.

Texas_Emerging_Technology_Fund

Texas Emerging Technology Fund Grant	6 Months Ended
	Jun. 30, 2014
Text Block [Abstract]	'
Texas Emerging Technology Fund Grant	'
	4	Texas Emerging Technology Fund Grant
	In August 2010, we were awarded a $2.0 million grant from the Texas Emerging Technology Fund, a program managed by the Governor’s office of the Sate of Texas, which provides economic development tools to support qualified start-up technologies in the state of Texas. The grant was to be funded in two tranches, one for $0.8 million, received in 2010, and the other for $1.2 million, received in 2011, based upon the achievement of certain milestones, which we achieved. As part of the terms of the award, we agreed to pay to the state an amount equal to the awards received, together with simple interest thereon at a rate of 8.0%, upon the occurrence of an event of default, which included the relocation of our principal place of business or principal executive offices to a location outside the state of Texas. Our obligation to repay the amount of the funds received upon an event of default expires upon the earlier date of a qualifying liquidation event or 10 years from the date of the award. We accounted for this repayment right as a derivative with changes in fair value of this instrument to be recognized through our statement of operations each period. At the date of issuance and as of June 30, 2014 and 2013, the fair value of this obligation was determined to be inconsequential given the likelihood that we would maintain our principal place of business or headquarters in Texas.

Defined_Contribution_Plan

Defined Contribution Plan	6 Months Ended
	Jun. 30, 2014
Postemployment Benefits [Abstract]	'
Defined Contribution Plan	'
	5	Defined Contribution Plan
	In March, 2014, we began to sponsor a 401(k) retirement plan, in which substantially all of our full-time employees are eligible to participate. Eligible participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. Irrespective of the amount of any participant contributions in a plan year, we will contribute an amount equal to 3% of each participant’s annual salary into their account in the plan each plan year, subject to federal limits per employee for safe harbor plans such as the plan we have offered. For the three months and six months ended June 30, 2014, we made safe harbor contributions into the plan totaling $43,000 and $58,000, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	6	Commitments and Contingencies
	Commitments
	We have various manufacturing, clinical, research and other contracts with vendors in the conduct of the normal course of business. As of June 30, 2014, we had a purchase commitment for approximately $0.5 million with an equipment vendor for the manufacture of equipment to produce our product. All other significant contracts as of June 30, 2014 were terminable, with varying provisions regarding termination. If a contract with a specific vendor were to be terminated, we would only be obligated for the product or services that we had received at the time the termination became effective.
	Contingencies
	While there are no legal proceedings we are aware of, we may become party to various claims and complaints arising from the ordinary course of business. We do not believe that any ultimate liability resulting from any such claims will have a material adverse effect on our results of operations, financial position or liquidity.

Subsequent_Events

Subsequent Events	6 Months Ended
	Jun. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	7	Subsequent Events
	In July 2014, we entered into a lease agreement with Harvard Investment Company for the lease of 6,370 square feet of space in Redwood City, CA for executive use. The term of the lease is for 36 months, commencing on September 1, 2014, with an option to extend the lease for one three-year period at the then market rate. Rent is due and payable on the first day of each month of the lease term. Monthly rent expense under this lease will approximate $24,393 on a straight-line basis.
	In July 2014, we entered into a Credit and Security Agreement (Credit Agreement) with MidCap Financial SBIC, LP (MidCap) for a $20 million credit facility, secured by all of our assets, with a negative pledge against our intellectual property. The credit facility is structured in two $10 million tranches, with the first tranche to be drawn at closing and the second tranche to be drawn after we provide evidence to MidCap of positive data based upon pre-specified endpoints in our ZS004 clinical study, but before its expiration on October 31, 2014. Notes issued under the terms of the Credit Agreement will bear interest at the rate of 7.5% per annum, payable monthly, have principal payable in 36 monthly installments commencing on January 1, 2016 and are subject to a $50,000 fee payable to MidCap upon closing. On January 1, 2019, the maturity date of the notes, we will owe MidCap an exit fee equal to 6.5% of the amount of notes funded under the Credit Agreement. We issued a note payable to MidCap in the amount of $10 million for the first tranche on July 14, 2014.

Nature_of_Business_and_Summary1

Nature of Business and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Organization	'
	Organization
	ZS Pharma Inc. is a biopharmaceutical company focused on the development and commercialization of highly selective, non-absorbed drugs to treat renal, cardiovascular, liver and metabolic diseases. Our proprietary zirconium silicate technology allows us to create highly selective ion traps that can reduce toxic levels of specific electrolytes without disturbing the balance of other electrolytes. We are currently conducting a Phase III study with our lead product candidate, ZS9 for the treatment of hyperkalemia, a life-threatening condition in which elevated levels of potassium increase the risk of muscle dysfunction, including cardiac arrhythmias and sudden cardiac death.
	On June 17, 2014, our registration statement on Form S-1 (File No. 333-195961) relating to our initial public offering (IPO) of our common stock was declared effective by the Securities and Exchange Commission (SEC). Our shares began trading on The NASDAQ Global Select Market on June 18, 2014. The public offering price of the shares sold in the offering was $18.00 per share. The IPO closed on June 23, 2014 and included 6,836,111 shares of common stock, which included 891,667 shares of common stock issued pursuant to the option granted to the underwriters to purchase additional shares. We received total proceeds from the offering of $114.4 million, net of underwriting discounts and commissions of $8.6 million. After deducting offering expenses of approximately $2.2 million, net proceeds were approximately $112.2 million. Upon the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 11,979,479 shares of common stock.
	Upon the effectiveness of the Amended and Restated Certificate of Incorporation of the Company on June 23, 2014, the number of shares of capital stock the Company is authorized to issue was increased to 255,000,000 shares, of which 250,000,000 shares are common stock and 5,000,000 shares are preferred stock. Both the common stock and preferred stock have a par value of $0.001 per share. There were no shares of preferred stock outstanding at June 30, 2014.
Basis of Presentation	'
	Basis of Presentation
	The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements.
	The condensed interim balance sheet as of June 30, 2014, and the interim condensed statements of operations for the three and six months ended June 30, 2014 and 2013, and the condensed statements of cash flows for the six months ended June 30, 2014 and 2013, are unaudited. The unaudited interim condensed financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly our financial position as of June 30, 2014, and our results of operations for the three and six months ended June 30, 2014 and 2013, and cash flows for the six months ended June 30, 2014 and 2013. The financial data and the other financial information disclosed in these notes to the financial statements related to the three-month periods and the six-month periods, are also unaudited. The results of operations for the three months ended June 30, 2014, are not necessarily indicative of the results to be expected for the year ending December 31, 2014, or for any other future annual or interim period. The condensed balance sheet as of December 31, 2013 included herein was derived from the audited financial statements as of that date. These financial statements should be read in conjunction with our audited financial statements included in our prospectus dated June 17, 2014, filed with the SEC pursuant to Rule 424(b)(4) of the Securities Act.
Reverse Stock Split	'
	Reverse Stock Split
	In June 2014, our board of directors and our stockholders approved an amendment to our amended and restated certificate of incorporation to effect a reverse split of shares of our common stock on a 1-for-2.56437 basis (the Reverse Stock Split). The par values and the authorized shares of the common and convertible preferred stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock, convertible preferred stock, options for common stock, warrants for common and preferred stock, and per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The Reverse Stock Split was made effective on June 11, 2014.
Use of Estimates	'
	Use of Estimates
	The preparation of the financial statements in accordance with U.S. GAAP requires management to make certain estimates and judgments that affect the reported amounts of assets, liabilities, and expenses. Actual results could differ from those estimates.
	We estimate our clinical trial expense accrual for a given period based on the number of patients enrolled at each site and the length of time each patient has been in the trial, less amounts previously billed, plus any ancillary clinical trial expenses that have been incurred but not yet recorded.
	We measure and recognize compensation expense for all stock options granted to our employees and directors, based on the estimated fair value of the award on the grant date. We use the Black-Scholes valuation model to estimate the fair value of stock option awards. The fair value is recognized as expense, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award on a straight-line basis. We believe that the fair value of stock options granted to non-employees is more reliably measured than the fair value of the services received. As such, the fair value of the unvested portion of the options granted to non-employees is re-measured each period. The resulting increase in value, if any, is recognized as expense during the period the related services are rendered. The determination of the grant-date fair value of options using an option-pricing model is affected by our estimated common stock fair value, as well as assumptions regarding a number of other complex and subjective variables.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents
	We consider all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. We place our cash with institutions with high credit quality. However, at certain times such cash may be in excess of Federal Deposit Insurance Corporation and Securities Investor Protection Corporation insurance limits. The carrying amount of cash approximates fair value.
Restricted Cash	'
	Restricted Cash
	On November 22, 2013, we executed an agreement to pledge, assign, transfer, and grant a security interest to J.P. Morgan Bank to secure the payment and performance of our credit card program. We have agreed to maintain $150,000 in a restricted cash account, given we are a pre-revenue company.
Redeemable Preferred Stock Warrant Liability	'
	Redeemable Preferred Stock Warrant Liability
	Freestanding warrants for shares that were either puttable or redeemable were classified as liabilities on the balance sheet and were carried at their estimated fair value. The Series B Redeemable Preferred Stock, which was able to be purchased with the warrants, was redeemable at a future date in 2017. As such, these warrants were classified as liabilities, and at the end of each reporting period, changes in the estimated fair value during the period were recorded in other income (expense). Prior to June 17, 2014, the warrants were all exercised into Series B Redeemable Preferred Stock, which was converted into Common Stock upon the IPO, and the amount of warrant liability was reclassified to shareholders’ equity.
Fair Value Measurements	'
	Fair Value Measurements
	ASC 820, Fair Value Measurement, provides a comprehensive framework for measuring the fair value of assets and liabilities, which provides for consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases require, estimates of fair market value.
	Financial assets and liabilities that have recurring fair value measurements are shown below (in thousands):
					Fair Value Measurements at
					December 31, 2013, Using
					Quoted		Significant		Significant
					Prices in		Other		Unobservable
					Active		Observable		Inputs
					Markets for		Inputs
					Identical
					Assets
	Description	Total			Level 1		Level 2		Level 3
	Financial liabilities:
	Series B Redeemable Preferred Stock warrants	$	2,667		$	—	$	—	$	2,667
	Total financial liabilities	$	2,667		$	—	$	—	$	2,667
	Level 3 liabilities comprise redeemable preferred stock warrant liabilities. These warrants were classified as liabilities because the Series B Redeemable Preferred shares that were able to be purchased by these warrants were redeemable and, therefore, are classified as temporary equity. The following table sets forth a summary of the changes in the estimated fair value of our redeemable preferred stock warrants, which were measured at fair value on a recurring basis (in thousands):
	Balance as of December 31, 2013	$	2,667
	Net increase in fair value		3,071
	Amount reclassified to shareholders’ equity upon exercise		(5,738	)
	Balance as of June 30, 2014	$	—
	The fair value of the outstanding Series B Redeemable Preferred Stock warrants was measured using the Black-Scholes option-pricing model. Inputs used to determine estimated fair value included the estimated fair value of the warrant, as determined by the fair value of the underlying stock relative to the warrant exercise price at the valuation measurement date, volatility of the price of the underlying stock, the remaining contractual term of the warrants, risk-free interest rates, and expected dividends.
	We believe the recorded values of cash and cash equivalents, other current assets, accounts payable, and accrued expenses approximate fair value because of the short maturity of these financial instruments.
Income Taxes	'
	Income Taxes
	We account for income taxes using the asset and liability approach in accordance with the provision of ASC 740, Income Taxes. Under this approach, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We continue to record a valuation allowance for the full amount of deferred tax assets, which would otherwise be recorded for tax benefits relating to the operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not.
	We account for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, we recognize the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. As of June 30, 2014 and 2013, we had no uncertain tax positions and no interest or penalties have been charged us from inception through June 30, 2014. If incurred, we will classify any interest and penalties as a component of tax expense.
	In April 2014, we determined that we had a change of ownership, as defined under Internal Revenue Code Section 382 (Section 382), at the time of the closing of the first tranche of Series C Redeemable Preferred Stock in October 2012. According to the provisions of Section 382, our net operating losses and research credits will be subject to an annual limitation. We have not yet determined the amount of the annual limitations to our net operating losses or research credits.
Comprehensive Income (Loss)	'
	Comprehensive Income (Loss)
	Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions, and other events and circumstances from non-owner sources. For the three months ended June 30, 2014 and 2013 and the six months ended June 30, 2014 and 2013, net loss equaled comprehensive loss.
Net Loss per Common Share Attributable to Common Shareholders	'
	Net Loss per Common Share Attributable to Common Shareholders
	Basic net loss per share attributable to common shareholders is calculated by dividing the net loss attributable to common shareholders by the weighted-average number of common shares outstanding during the period without consideration for common stock equivalents. Diluted net loss per share of common stock is the same as basic net loss per share of common stock, since the effects of potentially dilutive securities are antidilutive. The net loss per share of common stock attributable to common shareholders was computed using the two-class method required for participating securities. All series of our convertible preferred stock were considered to be participating securities as they were entitled to participate in undistributed earnings with shares of common stock. Due to our net loss, there was no impact on the earnings per share calculation in applying the two-class method since the participating securities had no legal requirement to share in any losses.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In June 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-10, which eliminates the financial reporting distinction between development stage entities and other reporting entities, thereby eliminating the requirements to present inception-to-date information in the statements of operations and stockholders’ equity and cash flow, or label the financial statements as those of a development stage entity. The Company has elected to early adopt this guidance, as permitted, for its financial statements for the year ended December 31, 2014, including this quarterly report, and therefore has no longer labeled its financial statements as those of a development stage entity or included any inception-to-date information.

Nature_of_Business_and_Summary2

Nature of Business and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	'
	Financial assets and liabilities that have recurring fair value measurements are shown below (in thousands):
					Fair Value Measurements at
					December 31, 2013, Using
					Quoted		Significant		Significant
					Prices in		Other		Unobservable
					Active		Observable		Inputs
					Markets for		Inputs
					Identical
					Assets
	Description	Total			Level 1		Level 2		Level 3
	Financial liabilities:
	Series B Redeemable Preferred Stock warrants	$	2,667		$	—	$	—	$	2,667
	Total financial liabilities	$	2,667		$	—	$	—	$	2,667
Summary of Changes in Estimated Fair Value of Redeemable Preferred Stock Warrants	'
	The following table sets forth a summary of the changes in the estimated fair value of our redeemable preferred stock warrants, which were measured at fair value on a recurring basis (in thousands):
	Balance as of December 31, 2013	$	2,667
	Net increase in fair value		3,071
	Amount reclassified to shareholders’ equity upon exercise		(5,738	)
	Balance as of June 30, 2014	$	—
Outstanding Shares of Common Stock Equivalents Excluded from Computation 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 shareholders for the periods presented as the effect of including such securities would be antidilutive:
		Six Months
		Ended June 30
		2014			2013
	Convertible preferred stock – as converted to common stock		—			7,478,998
	Warrants to purchase convertible preferred stock – as converted to common stock		—			377,743
	Warrants to purchase common stock		—			445,538
	Options to purchase common stock		4,229,864			2,308,044
			4,229,864			10,610,323

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Summary of Stock Option Activity	'
	Our stock option activity and related information are summarized as follows:
		Outstanding Options
		Number		Weighted-		Weighted-
		of Shares		Average		Average
				Exercise		Remaining
				Price		Contractual
						Life in
						Years
	Options outstanding at December 31, 2013		3,286,870	$	2.05		8.77
	Options granted		300,401		5.62		9.82
	Options exercised		—		—		—
	Options forfeited		—		—		—
	Options outstanding at March 31, 2014		3,587,271		2.36		8.63
	Options granted		642,593		15.14		9.86
	Options exercised		—		—		—
	Options forfeited		—		—		—
	Options outstanding at June 30, 2014		4,229,864	$	4.29		8.61
	Exercisable at June 30, 2014		1,058,496	$	1.86		7.42
Schedule of Grant Date Fair Value Options	'
	The Company utilized a Monte Carlo simulation method to estimate the fair value of these options on the grant date, and the following grant date fair values were calculated for each tranche of the award:
		Number of		Grant Date Fair Value
		Options
	IPO Scenario
	- Closing of Series D Preferred Stock Financing		31,641	$	144,931
	- Closing of IPO		158,206	$	538,520
			189,847	$	683,451

Nature_of_Business_and_Summary3

Nature of Business and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	0 Months Ended	6 Months Ended
	Jun. 23, 2014	Jun. 30, 2014	Dec. 31, 2013	Nov. 22, 2013
Restricted Cash and Investments [Line Items]	'	'	'	'
Common stock, shares outstanding	'	20,818,771	1,628,976	'
Common stock, shares issued	'	20,818,771	1,628,976	'
Proceeds from issue of common stock	'	$112,195,000	'	'
Payments for underwriting discounts and commissions	8,600,000	'	'	'
Net Proceeds from public offering	112,200,000	'	'	'
Convertible preferred stock outstanding	'	0	0	'
Common stock, shares authorized	250,000,000	250,000,000	49,574,865	'
Preferred stock, shares authorized	5,000,000	5,000,000	0	'
Common stock, par value	$0.00	$0.00	$0.00	'
Preferred Stock, par value	$0.00	$0.00	$0.00	'
Reverse Stock Split, Ratio	'	2.56437	'	'
Restricted cash	'	150,000	150,000	150,000
Maximum [Member]	'	'	'	'
Restricted Cash and Investments [Line Items]	'	'	'	'
Common stock, shares authorized	255,000,000	'	'	'
IPO [Member]	'	'	'	'
Restricted Cash and Investments [Line Items]	'	'	'	'
Common stock price per share	$18	'	'	'
Common stock, shares outstanding	6,836,111	'	'	'
Proceeds from issue of common stock	114,400,000	'	'	'
Public offering expenses	$2,200,000	'	'	'
IPO [Member] | Convertible Preferred Stock [Member]	'	'	'	'
Restricted Cash and Investments [Line Items]	'	'	'	'
Convertible preferred stock outstanding	11,979,479	'	'	'
Underwriter [Member]	'	'	'	'
Restricted Cash and Investments [Line Items]	'	'	'	'
Common stock, shares issued	891,667	'	'	'

Nature_of_Business_and_Summary4

Nature of Business and Summary of Significant Accounting Policies - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) (Recurring fair value measurements [Member], USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial liabilities:	'
Total financial liabilities	$2,667
Series B Preferred Stock [Member]	'
Financial liabilities:	'
Series B Redeemable Preferred Stock warrants	2,667
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]	'
Financial liabilities:	'
Total financial liabilities	'
Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Series B Preferred Stock [Member]	'
Financial liabilities:	'
Series B Redeemable Preferred Stock warrants	'
Significant Other Observable Inputs, Level 2 [Member]	'
Financial liabilities:	'
Total financial liabilities	'
Significant Other Observable Inputs, Level 2 [Member] | Series B Preferred Stock [Member]	'
Financial liabilities:	'
Series B Redeemable Preferred Stock warrants	'
Significant Unobservable Inputs, Level 3 [Member]	'
Financial liabilities:	'
Total financial liabilities	2,667
Significant Unobservable Inputs, Level 3 [Member] | Series B Preferred Stock [Member]	'
Financial liabilities:	'
Series B Redeemable Preferred Stock warrants	$2,667

Nature_of_Business_and_Summary5

Nature of Business and Summary of Significant Accounting Policies - Summary of Changes in Estimated Fair Value of Redeemable Preferred Stock Warrants (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014
Summary Of Changes In Fair Value Of Warrant Liability [Abstract]	'
Beginning balance	$2,667
Net increase in fair value	3,071
Amount reclassified to shareholders' equity upon exercise	-5,738
Ending balance	'

Nature_of_Business_and_Summary6

Nature of Business and Summary of Significant Accounting Policies - Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Common Share (Detail)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	4,229,864	10,610,323
Convertible Preferred Stock One [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	'	7,478,998
Warrants To Purchase Convertible Preferred Stock [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	'	377,743
Warrants To Purchase Common Stock [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	'	445,538
Options To Purchase Common Stock [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	4,229,864	2,308,044

ShareBased_Compensation_Additi

Share-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended			6 Months Ended			0 Months Ended	6 Months Ended
In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jan. 25, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014
						Series D Preferred Stock [Member]	Chief Executive Officer [Member]	IPO [Member]	Share Based Compensation Award Tranche One [Member]	Share Based Compensation Award Tranche Two [Member]
									Series D Preferred Stock [Member]	IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'
Shares of common stock available for granting under employee stock option plan	5,010,977	'	'	5,010,977	'	'	'	'	'	'
Number of options	642,593	300,401	'	189,847	'	31,641	189,847	158,206	31,641	158,206
Vesting period	'	'	'	'	'	'	'4 years	'	'	'
Aggregate intrinsic value of options exercisable	$28.50	'	'	$28.50	'	'	'	'	'	'
Aggregate intrinsic value of options outstanding	103.4	'	'	103.4	'	'	'	'	'	'
Weighted-average grant-date fair value of options granted	$12.55	'	$3.51	$10.02	$3.51	'	'	'	'	'
Total compensation cost related to nonvested awards not yet recognized	$13.60	'	'	$13.60	'	'	'	'	'	'
Weighted-average period of nonvested awards expected to be recognized	'	'	'	'2 years 11 months 27 days	'	'	'	'	'	'

ShareBased_Compensation_Summar

Share-Based Compensation - Summary of Stock Option Activity (Detail) (USD $)	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'	'
Number of Shares, Options outstanding, beginning balance	3,587,271	3,286,870	3,286,870	'
Weighted-Average Exercise Price Options outstanding, beginning balance	$2.36	$2.05	$2.05	'
Number of Shares, Options granted	642,593	300,401	189,847	'
Number of Shares, Options exercised	'	'	'	'
Number of Shares, Options forfeited	'	'	'	'
Number of Shares, Options outstanding, ending balance	4,229,864	3,587,271	4,229,864	3,286,870
Number of Shares, Exercisable, ending balance	1,058,496	'	1,058,496	'
Weighted-Average Exercise Price, Options granted	$15.14	$5.62	'	'
Weighted-Average Exercise Price, Options exercised	'	'	'	'
Weighted-Average Exercise Price, Options forfeited	'	'	'	'
Weighted-Average Exercise Price, Options outstanding, ending balance	$4.29	$2.36	$4.29	$2.05
Weighted-Average Exercise Price, Exercisable, ending balance	$1.86	'	$1.86	'
Weighted-Average Remaining Contractual Life in Years, Options granted	'	'9 years 9 months 26 days	'9 years 10 months 10 days	'
Weighted-Average Remaining Contractual Life in Years, Options outstanding	'	'8 years 7 months 17 days	'8 years 7 months 10 days	'8 years 9 months 7 days
Weighted-Average Remaining Contractual Life in Years, Exercisable	'	'	'7 years 5 months 1 day	'

ShareBased_Compensation_Schedu

Share-Based Compensation - Schedule of Grant Date Fair Value Options (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Number of options	642,593	300,401	189,847
Grant Date Fair Value	'	'	$683,451
Series D Preferred Stock [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Number of options	'	'	31,641
Grant Date Fair Value	'	'	$144,931
IPO [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Number of options	'	'	158,206
Grant Date Fair Value	'	'	$538,520

Preferred_Stock_Additional_Inf

Preferred Stock - Additional Information (Detail) (USD $)

6 Months Ended

1 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 23, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Feb. 28, 2014

Jun. 30, 2014

Jun. 05, 2014

Series A Preferred Stock [Member]

Series A Preferred Stock [Member]

Series B Preferred Stock [Member]

Series B Preferred Stock [Member]

Series C Preferred Stock [Member]

Series C Preferred Stock [Member]

Series D Preferred Stock [Member]

Series B Warrant [Member]

Series B Warrant [Member]

Series B Preferred Stock [Member]

Capital Unit [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Convertible preferred stock, shares outstanding

0

'

0

'

582,965

'

'

'

'

'

'

'

Convertible preferred stock, shares outstanding

'

'

'

'

'

'

2,261,488

'

6,899,275

'

'

'

Convertible preferred stock, shares issued

'

'

'

'

'

'

2,261,488

'

6,899,275

1,858,008

'

'

Convertible preferred stock, par value

'

'

'

'

'

$0.00

$0.00

$0.00

$0.00

$0.00

'

'

Original issue price

'

'

'

'

'

'

'

'

'

$13.46

'

'

Proceeds from issuance of redeemable preferred stock

'

'

'

'

'

'

'

'

'

$25,000,000

'

'

Warrants exercised to purchase shares

'

'

'

'

'

'

'

'

'

'

'

377,743

Proceeds from Warrant exercises, Gross

$3,780,000

'

'

'

'

'

'

'

'

'

$1,400,000

'

Preferred Stock shares authorized

5,000,000

5,000,000

0

'

1,494,966

'

'

'

'

'

'

'

Preferred Stock, par value

$0.00

$0.00

$0.00

$0.00

$0.00

'

'

'

'

'

'

'

Conversion of preferred shares into common shares

'

11,979,479

'

'

'

'

'

'

'

'

'

'

Texas_Emerging_Technology_Fund1

Texas Emerging Technology Fund Grant - Additional Information (Detail) (TEXAS, USD $)	1 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Aug. 31, 2010	Dec. 31, 2011
TEXAS	'	'
Loss Contingencies [Line Items]	'	'
Grant awarded, net	$2	'
Grant received	$0.80	$1.20
Interest rate	'	8.00%
Obligation to repay awards	'	'10 years

Defined_Contribution_Plan_Addi

Defined Contribution Plan - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	6 Months Ended
	Mar. 31, 2014	Jun. 30, 2014	Jun. 30, 2014
Compensation And Retirement Disclosure [Abstract]	'	'	'
Contribution, percent of employees	3.00%	'	'
Safe harbour contributions into 401(k) retirement plan	'	$43,000	$58,000

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	Jun. 30, 2014
In Millions, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]	'
Purchase commitment amount	$0.50

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	6 Months Ended	1 Months Ended		1 Months Ended
	Jun. 30, 2014	Jul. 31, 2014	Jul. 14, 2014	Jul. 31, 2014	Jul. 31, 2014
	MidCap Financial SBIC LP [Member]	Subsequent Events [Member]	Subsequent Events [Member]	Subsequent Events [Member]	Subsequent Events [Member]
		MidCap Financial SBIC LP [Member]	MidCap Financial SBIC LP [Member]	MidCap Financial SBIC LP [Member]	Harvard Investment Company [Member]
				Line of Credit [Member]	sqft
				Tranches
Subsequent Event [Line Items]	'	'	'	'	'
Rental space	'	'	'	'	6,370
Lease agreement period	'	'	'	'	'36 months
Lease extension period	'	'	'	'	'3 years
Lease rental expense	'	'	'	'	$24,393
Line of credit facility maximum amount	'	20,000,000	'	'	'
Credit facility amount	'	10,000,000	'	'	'
Number of tranches	'	'	'	2	'
Credit facility expiration date	31-Oct-14	'	'	'	'
Debt instrument interest percentage	'	7.50%	'	'	'
Number of installments for principal payments	'36 months	'	'	'	'
Debt instrument fee amount	'	50,000	'	'	'
Debt instrument maturity date	1-Jan-19	'	'	'	'
Debt instrument redemption percentage	'	6.50%	'	'	'
Notes payable issue for first tranche	'	'	$10,000,000	'	'