ViewRay (VRAYQ) 10-Q 7 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 27, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	ViewRay, Inc.
Entity Central Index Key	1,597,313
Document Type	10-Q
Trading Symbol	VRAY
Document Period End Date	Jun. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		75,206,716
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2,018

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 66,143	$ 57,389
Accounts receivable	13,563	20,326
Inventory	28,570	19,375
Deposits on purchased inventory	7,542	7,043
Deferred cost of revenue	15,683	13,696
Prepaid expenses and other current assets	5,259	4,862
Total current assets	136,760	122,691
Property and equipment, net	13,587	11,564
Restricted cash	1,181	1,143
Intangible assets, net	68	78
Other assets	917	235
TOTAL ASSETS	152,513	135,711
Current liabilities:
Accounts payable	7,574	11,014
Accrued liabilities	7,650	7,207
Customer deposits	10,280	17,820
Deferred revenue, current portion	15,540	20,151
Total current liabilities	41,044	56,192
Deferred revenue, net of current portion	4,393	3,238
Long-term debt	44,599	44,504
Warrant liabilities	15,411	22,420
Other long-term liabilities	9,100	7,370
TOTAL LIABILITIES	114,547	133,724
Commitments and contingencies (Note 6)	0	0
Stockholders’ equity:
Convertible preferred stock, par value of $0.01 per share; 10,000,000 shares authorized at June 30, 2018 and December 31, 2017; no shares issued and outstanding at June 30, 2018 and December 31, 2017	0	0
Common stock, par value of $0.01 per share; 300,000,000 shares authorized at June 30, 2018 and December 31, 2017; 75,188,832 and 67,653,974 shares issued and outstanding at June 30, 2018 and December 31, 2017	741	666
Additional paid-in capital	386,610	321,174
Accumulated deficit	(349,385)	(319,853)
TOTAL STOCKHOLDERS’ EQUITY	37,966	1,987
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 152,513	$ 135,711

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	75,188,832	67,653,974
Common stock, shares outstanding	75,188,832	67,653,974

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Total revenue	$ 16,443	$ 698	$ 42,633	$ 1,925
Cost of revenue:
Total cost of revenue	16,374	826	36,994	1,868
Gross margin	69	(128)	5,639	57
Operating expenses:
Research and development	4,389	3,251	8,159	6,165
Selling and marketing	3,394	1,871	6,640	2,943
General and administrative	10,503	7,463	20,349	14,614
Total operating expenses	18,286	12,585	35,148	23,722
Loss from operations	(18,217)	(12,713)	(29,509)	(23,665)
Interest income	2	1	4	2
Interest expense	(1,918)	(1,792)	(3,784)	(3,529)
Other (expense) income, net	(1,857)	6,151	6,485	(9,122)
Loss before provision for income taxes	(21,990)	(8,353)	(26,804)	(36,314)
Provision for income taxes	0	0	0	0
Net loss and comprehensive loss	(21,990)	(8,353)	(26,804)	(36,314)
Amortization of beneficial conversion feature related to Series A convertible preferred stock	0	0	(2,728)	0
Net loss attributable to common stockholders, basic and diluted	$ (21,990)	$ (8,353)	$ (29,532)	$ (36,314)
Net loss per share, basic and diluted	$ (0.30)	$ (0.15)	$ (0.41)	$ (0.67)
Weighted-average common shares used to compute net loss per share attributable to common stockholders, basic and diluted	74,531,274	57,230,403	71,776,802	54,540,854
Product
Revenue:
Total revenue	$ 15,366	$ 0	$ 40,745	$ 0
Cost of revenue:
Total cost of revenue	14,654	328	34,365	594
Service
Revenue:
Total revenue	958	579	1,650	1,687
Cost of revenue:
Total cost of revenue	1,720	498	2,629	1,274
Distribution Rights
Revenue:
Total revenue	$ 119	$ 119	$ 238	$ 238

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (21,990)	$ (8,353)	$ (26,804)	$ (36,314)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization			1,586	1,004
Stock-based compensation			2,873	1,782
Accretion on asset retirement obligation			20	19
Change in fair value of warrant liabilities			(7,009)	9,032
Loss on disposal of property and equipment			0	9
Amortization of debt discount and interest accrual			1,770	1,605
Changes in operating assets and liabilities:
Accounts receivable			6,763	2,380
Inventory			(10,312)	(7,276)
Deposits on purchased inventory			(499)	(2,994)
Deferred cost of revenue			(2,447)	(7,254)
Prepaid expenses and other assets			(1,079)	(2,096)
Accounts payable			(3,383)	1,808
Accrued expenses and other long-term liabilities			679	976
Customer deposits and deferred revenue			(10,996)	13,436
Net cash used in operating activities			(48,838)	(23,883)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment			(2,280)	(776)
Net cash used in investing activities			(2,280)	(776)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from common stock private placement, gross			0	26,100
Proceeds from the exercise of stock options			715	193
Net cash provided by financing activities			59,910	64,388
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH			8,792	39,729
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — BEGINNING OF PERIOD			58,532	15,341	$ 15,341
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — END OF PERIOD	$ 67,324	$ 55,070	67,324	55,070	58,532
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest			2,014	1,924
Cash paid for taxes			0	1
SUPPLEMENTAL NON-CASH INVESTING AND FINANCING ACTIVITIES:
Transfer of property and equipment from inventory and deferred cost of revenue			1,577	0
Purchase of property and equipment in accounts payable and accrued expenses			13	248
Offering cost in accounts payable and accrued expenses			0	6
Private Placement
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of offering costs related to common stock issuance			0	(300)
At The Market Offering Program
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of offering costs related to common stock issuance			(6)	(1,129)
Proceeds from offering of common stock, gross			278	39,524	$ 40,100
Direct Registered Offering
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of offering costs related to common stock issuance			(177)
Proceeds from offering of common stock, gross			$ 59,100	$ 0

Background and Organization

Background and Organization	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Background and Organization	1. Background and Organization ViewRay, Inc., or ViewRay or the Company, and its wholly owned subsidiary ViewRay Technologies, Inc., designs, manufactures and markets MRIdian, an MR Image-Guided radiation therapy system to simultaneously image and treat cancer patients. Since inception, ViewRay Technologies, Inc. has devoted substantially all of its efforts towards research and development, initial selling and marketing activities, raising capital and the manufacturing and shipment of MRIdian systems. In May 2012, ViewRay Technologies, Inc. was granted clearance from the U.S. Food and Drug Administration, or FDA, to sell MRIdian with Cobalt-60. In November 2013, ViewRay Technologies, Inc. received its first clinical acceptance of a MRIdian with Cobalt-60 at a customer site, and the first patient was treated with that system in January 2014. ViewRay Technologies, Inc. has had the right to affix the CE mark to MRIdian with Cobalt-60 in the European Economic Area since November 2014. In September 2016, the Company received the rights to affix the CE mark to MRIdian Linac, and in February 2017, the Company received 510(k) clearance from the FDA to market MRIdian Linac. The Company’s condensed consolidated financial statements have been prepared on the basis of the Company continuing as a going concern for a reasonable period of time. The Company’s principal sources of liquidity are cash flows from public and private offerings of capital stock and available borrowings under its term loan agreement, as well as cash from the sale of its systems and services. These have historically been sufficient to meet working capital needs, capital expenditures, and debt service obligations. During the six months ended June 30, 2018, the Company incurred a net loss of $26.8 million and used cash in operations of $48.8 million. The Company believes that its existing cash balance of $66.1 million as of June 30, 2018, together with anticipated cash receipts from equity financing and sales of MRIdian systems will be sufficient to fund its operations for at least the next 12 months.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States, or GAAP, and pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC. The condensed consolidated financial statements include the accounts of ViewRay, Inc. and its wholly owned subsidiary, ViewRay Technologies, Inc. All inter-company accounts and transactions have been eliminated in consolidation. In the opinion of management, all adjustments, including normal recurring adjustments, considered necessary for a fair presentation of the Company’s unaudited condensed consolidated financial statements, have been included. The results of operations for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 or any future period. These unaudited condensed consolidated financial statements and their notes should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2017. Effective January 1, 2018, the Company adopted Accounting Standard Codification Topic 606, or ASC 606, Revenues from Contracts with Customers, Significant Accounting Policies The significant accounting policies used in preparation of these condensed consolidated financial statements are disclosed in the notes to consolidated financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 filed with the SEC on March 12, 2018, and have not changed significantly since that filing, except for the impact of the adoption of the new accounting guidance related to revenue recognition. Revenue Recognition The Company derives revenues primarily from the sale of MRIdian systems and related services as well as support and maintenance services on sold systems. The Company accounts for revenue contracts with customers by applying the requirements of ASC 606, which includes the following steps: • Identification of the contract, or contracts, with a customer; • Identification of the performance obligations in the contract; • Determination of the transaction price; • Allocation of the transaction price to the performance obligations in the contract; and • Recognition of revenue when, or as, the Company satisfies a performance obligation. In all sales arrangements, revenues are recognized when control of the promised goods or services are transferred to customers, in an amount that reflects the consideration the Company expects to be entitled to receive in exchange for those goods or services. For sales of MRIdian systems that the Company is required to install at the customer site, product revenue is recognized upon receipt of customer acceptance. For sales of MRIdian systems for which the Company is not responsible for installing, product revenue is recognized when the entire system is delivered and control of the system is transferred to the customer. For sales of the related support and maintenance services, a time-elapsed method is used to measure progress toward complete satisfaction of performance obligations and service revenue is recognized ratably over the service contract term, which is typically 12 months. Arrangements with Multiple Performance Obligation The Company frequently enters into sales arrangements that include multiple performance obligations, which mainly consist of (i) sale of MRIdian systems, which generally includes installation and embedded software, and (ii) product support, which includes extended service and maintenance. For such arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price. The standalone selling price, or SSP, is determined based on observable prices at which the Company separately sells the products and services. If an SSP is not directly observable, the Company will estimate the SSP considering market conditions or internally approved pricing guidelines related to the performance obligations. Product Revenue Product revenue is derived primarily from the sales of MRIdian system. The system contains both software and non-software components that together deliver essential functionality. The Company’s customer contracts generally call for on-site assembly of the system components and system integration. Once the system installation is completed, the Company performs a detailed demonstration with the customer showing that the MRIdian system meets the standard product specifications. After successful demonstration, the customer signs a document indicating customer’s acceptance. For sales of MRIdian systems that the Company is required to install at the customer site, revenue recognition occurs when the customer acknowledges that the system operates in accordance with standard product specifications, the customer accepts the installed unit by signing the acceptance document and the control of the system is transferred to the customer. Certain customer contracts with distributors do not require ViewRay installation at the customer site, and the distributors typically have their own or engage a qualifying third-party certified technician to perform the installation. For sales of MRIdian systems for which the Company is not responsible for installation, revenue recognition occurs when the entire system is delivered, and the control of the system is transferred to the customer. Service Revenue Service revenue is derived primarily from maintenance services. The maintenance and support service is a stand-ready obligation which is performed over the term of the arrangement and, as a result, service revenue is recognized ratably over the service period as the customers benefit from the service throughout the service period. Distribution Rights Revenue In December 2014, the Company entered into a distribution agreement with Itochu Corporation pursuant to which it appointed Itochu as its exclusive distributor for the promotion, sale and delivery of MRIdian products within Japan. In consideration of the exclusive distribution rights granted, the Company received $4.0 million, which was recorded as deferred revenue. Starting in August 2016, distribution rights revenue is recognized ratably over the remaining term of the distribution agreement of approximately 8.5 years . The following table presents revenue disaggregated by types and geography (in thousands): Three Months Ended June 30, Six Months Ended June 30, U.S. 2018 2017 2018 2017 Product $ 6,053 $ — $ 19,588 $ — Service 502 312 898 1,191 Total U.S. revenue $ 6,555 $ 312 $ 20,486 $ 1,191 Outside of U.S. ("OUS") Product $ 9,313 $ — $ 21,157 $ — Service 456 267 752 496 Distribution rights 119 119 238 238 Total OUS revenue $ 9,888 $ 386 $ 22,147 $ 734 Total Product $ 15,366 $ — $ 40,745 $ — Service 958 579 1,650 1,687 Distribution rights 119 119 238 238 Total revenue $ 16,443 $ 698 $ 42,633 $ 1,925 Contract Balances The timing of revenue recognition, billings and cash collections results in short-term and long-term trade receivables, customer deposit, deferred revenues and deferred cost of revenue on the condensed consolidated balance sheets. Trade receivables are recorded at the original invoiced amount, net of an estimated allowance for doubtful accounts. Trade credit is generally extended on a short-term basis. The Company occasionally provides for long-term trade credit for its maintenance services so that the period between when the services are rendered to its customers and when the customers pay for that service is within one year. Thus, the Company’s trade receivables do not bear interest or contain significant financing component. Long-term trade receivables of $400 thousand are reported within other assets in the condensed consolidated balance sheets at June 30, 2018. These amounts are billed in accordance with the terms of the customer contracts to which they relate and are expected to be collected three to four years from the date of invoice as the underlying maintenance services are rendered. The Company had no long-term trade receivables at December 31, 2017. Trade receivables are periodically evaluated for collectability based on past credit history with customers and their current financial condition. Changes in the estimated collectability of trade receivables are recorded in the results of operations for the period in which the estimate is revised. Trade receivables that are deemed uncollectible are offset against the allowance for doubtful accounts. The Company generally does not require collateral for trade receivables. Based on the specific customers and the current economic conditions, there was no allowance for doubtful accounts recorded at June 30, 2018 or December 31, 2017. Customer deposits represent payments received in advance of system installation. For domestic and international sales, advance payments received prior to inventory shipments and customer acceptance are recorded as customer deposits. Advance payments are subsequently reclassified to deferred revenue upon inventory shipment when the title and risk of loss of inventory items transfer to customers. All customer deposits, including those that are expected to be a deposit for more than one year, are classified as current liabilities based on consideration of the Company’s normal operating cycle (the time between acquisition of the inventory components and the final cash collection from customers on these inventory components) which is in excess of one year. Deferred revenue consists of deferred product revenue and deferred service revenue. Deferred product revenue arises from timing differences between the fulfillment of contract obligations and satisfaction of all revenue recognition criteria consistent with the Company’s revenue recognition policy. Deferred service revenue results from the advance billing for services to be delivered over a period of time. Deferred revenues expected to be realized within one year or normal operating cycle are classified as current liabilities. Deferred cost of revenue consists of cost for inventory items that have been shipped with title and risk of loss transferred to the customer, but the customer acceptance has not been received. Deferred cost of revenue is included as part of current assets as the corresponding deferred product revenue is expected to be realized within one year or normal operating cycle. During the three and six months ended June 30, 2018, the Company recognized $6.8 million and $17.9 million revenue that was included in the deferred revenue balance at the beginning of each reporting period. During the three and six months ended June 30, 2017, the Company recognized $673.7 thousand and $735.5 thousand revenue that was included in the deferred revenue balance at the beginning of each reporting period. Practical Expedients Election As part of the Company's adoption of ASC 606, the Company elected to use the practical expedient to expense costs to obtain a contract as incurred when the amortization period would have been one year or less, which mainly includes the Company's internal sales force compensation program. Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, FASB, issued ASU No. 2016-02, Leases (Topic 842) In June 2018, the FASB issued ASU No. 2018-07 Compensation — Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting Recently Adopted Accounting Pronouncements In May 2014, the FASB issued ASC 606. Under the standard, revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration the entity expects to receive in exchange for those goods or services. Effective January 1, 2018, the Company adopted the requirements of ASC 606 using the full retrospective method. The adoption has no impact on the prior period financial statements, and the related disclosures required by the new standard have been updated in the “Significant Accounting Policies” section above. On January 1, 2018, the Company adopted ASU No.2016-15 , Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments Statement of Cash Flows (Topic 230): Restricted Cash Under ASU 2016-18, restricted cash and restricted cash equivalent amounts are presented along with cash and cash equivalents when reconciling the total beginning and ending amounts shown on the statement of cash flows. The Company reflected the impact of ASU No. 2016-18 to the comparative prior period which resulted in an increase in the beginning and ending cash, cash equivalents and restricted cash of $ In May 2017, the FASB issued ASU No. 2017-09 , Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting In the first quarter of 2018, the Company adopted ASU No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118,

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	3. Balance Sheet Components Property and Equipment Property and equipment consisted of the following (in thousands): June 30, 2018 December 31, 2017 Prototype $ 12,622 $ 11,929 Machinery and equipment 10,732 7,831 Leasehold improvements 4,327 4,438 Software 1,228 1,142 Furniture and fixtures 588 558 Property and equipment, gross 29,497 25,898 Less: accumulated depreciation and amortization (15,910 ) (14,334 ) Property and equipment, net $ 13,587 $ 11,564 Depreciation and amortization expense related to property and equipment were $923 thousand and $532 thousand during the three months ended June 30, 2018 and 2017, respectively; and $1.6 million and $994 thousand during the six months ended June 30, 2018 and 2017, respectively. Accrued Liabilities Accrued liabilities consisted of the following (in thousands): June 30, 2018 December 31, 2017 Accrued payroll and related benefits $ 4,049 $ 3,944 Accrued accounts payable 1,625 2,671 Sales and other tax payable 1,607 149 Accrued legal, accounting and professional fees 313 322 Other 56 121 Total accrued liabilities $ 7,650 $ 7,207 Deferred Revenue Deferred revenue consisted of the following (in thousands): June 30, 2018 December 31, 2017 Deferred revenue: Product $ 11,917 $ 18,861 Services 4,908 1,182 Distribution rights 3,108 3,346 Total deferred revenue 19,933 23,389 Less: current portion of deferred revenue (15,540 ) (20,151 ) Noncurrent portion of deferred revenue $ 4,393 $ 3,238 Other Long-Term Liabilities June 30, 2018 December 31, 2017 Accrued interest, noncurrent portion $ 7,894 $ 6,218 Deferred rent, noncurrent portion 378 167 Other 828 985 Total other-long term liabilities $ 9,100 $ 7,370

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	4. Fair Value of Financial Instruments The Company’s financial instruments that are carried at fair value mainly consist of Level 1 assets and Level 3 liabilities. Level 1 assets include highly liquid bank deposits and money market funds, which were not material at June 30, 2018 and December 31, 2017. Level 3 liabilities that are measured on a recurring basis consist of the 2017 and 2016 Placement Warrants, as described in Note 8. Placement warrant liabilities are valued using the Black-Scholes option-pricing model. Generally, increases (decreases) in the fair value of the underlying stock and estimated term would result in a directionally similar impact to the fair value of the warrants (see Note 10). The gains and losses from re-measurement of Level 3 financial liabilities are recorded as part of other income (expense), net in the condensed consolidated statements of operations. During the three and six months ended June 30, 2018, the Company recorded a loss of $1.2 million and a gain of $7.0 million, respectively, related to the change in fair value of the 2017 and 2016 Placement Warrants. During the three and six months ended June 30, 2017, the Company recorded a gain of $6.2 million and a loss of $9.0 million in other income (expense) within the statement of operations, respectively, related to the change in fair value of the 2017 and 2016 Placements Warrants. There have been no transfers between Level 1, Level 2 and Level 3 in any periods presented. The following table sets forth the fair value of the Company’s financial liabilities by level within the fair value hierarchy (in thousands): At June 30, 2018 Level 1 Level 2 Level 3 Total 2017 Placement Warrants Liability $ — $ — $ 8,582 $ 8,582 2016 Placement Warrants Liability — — 6,829 6,829 Total $ — $ — $ 15,411 $ 15,411 At December 31, 2017 Level 1 Level 2 Level 3 Total 2017 Placement Warrants Liability $ — $ — $ 12,487 $ 12,487 2016 Placement Warrants Liability — — 9,933 9,933 Total $ — $ — $ 22,420 $ 22,420 The following table sets forth a summary of the changes in fair value of the Company’s Level 3 financial liabilities (in thousands): Six Months Ended June 30, 2018 2017 Fair value, beginning of period $ 22,420 $ 2,723 Issuance of 2017 Placement Warrants — 3,373 Change in fair value of Level 3 financial liabilities (7,009 ) 9,032 Fair value, end of period $ 15,411 $ 15,128

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Debt Instruments [Abstract]
Debt	5. Debt CRG Term Loan In June 2015, ViewRay Technologies, Inc. entered into a Term Loan Agreement, or the CRG Term Loan, with Capital Royalty Partners II L.P., Capital Royalty Partners II – Parallel Fund “A” L.P., Capital Royalty Partners II (Cayman) L.P. and Parallel Investment Opportunities Partners II L.P. or together with their successors by assignment, CRG, for up to $50.0 million of which $30.0 million was made available to the Company upon closing with the remaining $20.0 million available on or before June 26, 2016 at its option upon the occurrence of either: (i) an initial public offering of its common stock on a nationally recognized securities exchange that raises a minimum of $40.0 million in net cash proceeds with a minimum of $120.0 million post-money valuation, or Qualifying IPO, or (ii) achievement of a minimum of $25.0 million gross revenue from the sales of the MRIdian system during any consecutive 12 months before March 31, 2016. The Company drew down the first $30.0 million on the closing date. The CRG Term Loan has a maturity date of June 26, 2020 and bears cash interest at a rate of 12.5% per annum to be paid quarterly during the interest-payment-only period of 3 years. In April 2017, the CRG Term Loan was amended to allow for interest-payment-only until March 31, 2020. During the interest-payment-only period, the Company has the option to elect to pay only 8% of the 12.5% per annum interest in cash, and the remaining 4.5% of the 12.5% per annum interest as compounded interest, or deferred payment in-kind interest, added to the aggregate principal amount of the CRG Term Loan. Principal payment and any deferred payment in-kind interest will be paid quarterly in equal installments following the end of the interest-payment-only period through maturity date. The CRG Term Loan is subject to a prepayment penalty of: 3% on the outstanding balance during the first 12 months following the funding of the Term Loan; 2% on the outstanding balance after year 1 but on or before year 2; 1% on the outstanding balance after year 2 but on or before year 3; and 0% on the outstanding loan if prepaid after year 3 thereafter until maturity. The Term Loan is also subject to a facility fee of 7% based on the sum of the amount drawn and any outstanding payment in-kind interest payable on the maturity date or the date the Term Loan becomes due. All direct financing costs were accounted for as a discount on the CRG Term Loan and will be amortized to interest expense during the life of the loan using the effective interest method. The CRG Term Loan is subject to financial covenants and is collateralized by essentially all assets of the Company and limits its ability with respect to additional indebtedness, investments or dividends, among other things, subject to customary exceptions. In March 2016, the Company and CRG executed an amendment to the original terms of the CRG Term Loan such that, with regard to the conditions for borrowing the remaining $20.0 million available under the CRG Term Loan, the Company may, at its election, draw down: (i) an amount of either $10.0 million or $15.0 million in up to two advances upon achievement of a minimum of $15.0 million of aggregate product and service revenue during any consecutive 12 month period ending on or before March 31, 2016; and (ii) an additional $5.0 million (or $10.0 million, if the previous draw made was only in an amount of $10.0 million) upon achievement of a minimum of $25.0 million of aggregate product and service revenue during any consecutive 12 month period ending on or before December 31, 2016 and upon execution of the first sales contract of the Company’s second generation product. The Company achieved the minimum of $15.0 million gross revenue requirement in March 2016, which made the first $15.0 million of the remaining $20.0 million credit facility immediately available for draw down. In May 2016, the Company drew down the additional $15.0 million available amount. In April 2017, the Company and CRG executed an amendment to the terms of its CRG Term Loan. Amendments to the CRG Term Loan include availability of the existing $5.0 million tranche at ViewRay’s option through June 30, 2017, the addition of a $15.0 million tranche of borrowing capacity available at ViewRay’s option through September 30, 2017, extension of the interest-only and payment in-kind period, a decrease to the combined 2016 and 2017 revenue covenant and a 1.75% increase to the facility fee. In October 2017, the Company and CRG executed another amendment to the terms of its CRG Term Loan, as amended in March 2016 and April 2017. This amendment extended the availability of the existing $15.0 million borrowing capacity through December 31, 2017. The Company did not draw down any amounts under the $5.0 million or the $15.0 million tranches and they have since expired. In February 2018, the Company and CRG executed an amendment to the terms of its CRG Term Loan to decrease the amount of the minimum combined 2016 and 2017 revenue covenant. At June 30, 2018, the Company had $45.0 million in outstanding debt and $5.9 million in deferred payment in-kind interest to CRG and was in compliance with all financial covenants under the CRG Term Loan.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Operating Leases The Company leases office space in Oakwood Village, Ohio and Mountain View, California under noncancelable operating leases. In April 2018, the Company entered into a lease agreement to lease additional office space located in Mountain View, California. The lease expires on the seventh anniversary of the commencement date, and the Company has the option to extend the term of the lease for a period of up to five years. In June 2018, the Company entered into an amendment to the existing Mountain View lease, extending the term of the original lease for a period of 68 months, and the extended lease expires on July 31, 2025. At June 30, 2018, the future minimum payments for the operating leases are as follows (in thousands): Year Ending December 31, Future Payments The remainder of 2018 $ 746 2019 2,039 2020 2,321 2021 2,391 2022 2,463 Thereafter 6,709 Total future minimum payments $ 16,669 Contingencies The Company is subject to claims and assessments from time to time in the ordinary course of business. The Company records a provision for a liability when it believes that it is both probable that a liability has been incurred and the amount can be reasonably estimated. Significant judgment is required to determine both probability and the estimated amount. In the normal course of business, the Company may become involved in legal proceedings. The Company will accrue a liability for legal proceedings when it is probable that a liability has been incurred and the amount can be reasonably estimated. When only a range of possible loss can be established, the most probable amount in the range is accrued. If no amount within this range is a better estimate than any other amount within the range, the minimum amount in the range is accrued. The accrual for a litigation loss contingency might include, for example, estimates of potential damages, outside legal fees and other directly related costs expected to be incurred. At June 30, 2018 and December 31, 2017, the Company was not involved in any material legal proceedings. Purchase Commitments At June 30, 2018 and December 31, 2017, the Company had no outstanding firm purchase commitments.

Distribution Agreement

Distribution Agreement	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Distribution Agreement	7. Distribution Agreement In December 2014, the Company entered into a distribution agreement with Itochu Corporation, or Itochu, a Japanese entity, pursuant to which the Company appointed Itochu as its exclusive distributor for the sale and delivery of the Company’s MRIdian products within Japan. The exclusive distribution agreement has an initial term of 10 years from December 2014 and contains features customary in these types of distribution agreements. Under this distribution agreement, the Company will supply its products and services to Itochu based upon the Company’s then-current pricing. In consideration of the exclusive distribution rights granted, Itochu agreed to pay a distribution fee of $4.0 million in three installments: (i) the first installment of $1.0 million was due upon execution of the distribution agreement; (ii) the second installment of $1.0 million was due within 10 business days following submission of the application for regulatory approval of the Company’s product to the Japan regulatory authority; and (iii) the final installment of $2.0 million was due within 10 business days following receipt of approval for the Company’s product from the Japanese Ministry of Health, Labor and Welfare. The distribution fee paid by Itochu was refundable if the Company failed to obtain the approval from the Japan regulatory authority before December 31, 2017. The first and second installments of $2.0 million in aggregate were received in December 2014 and December 2015, respectively. In August 2016, the Company received the third and final $2.0 million installment upon the receipt of regulatory approval to market MRIdian in Japan A time-elapsed method is used to measure progress because the control is transferred evenly over the remaining contractual period.

Equity Financing

Equity Financing	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Equity Financing	8. Equity Financing Private Placements In September 2016, the Company completed the final closing of a private placement offering, or the 2016 Private Placement, through which it sold (i) 4,602,506 shares of its common stock and (ii) warrants that provide the warrant holders the right to purchase 1,380,745 shares of common stock, or the 2016 Placement Warrants, and raised total gross proceeds of $13.8 million. The 2016 Placement Warrants have an exercise price of $2.95 per share, are exercisable at any time at the option of the holder and expire seven years from the date of issuance. In January 2017, the Company completed the final closing of a private placement offering, or the 2017 Private Placement, through which it sold (i) 8,602,589 shares of its common stock and (ii) warrants that provide the warrant holders the right to purchase 1,720,512 shares of common stock, or the 2017 Placement Warrants, and raised total gross proceeds of $26.1 million. The 2017 Placement Warrants have an exercise price of $3.17 per share, became exercisable in July 2017 and expire in January 2024. Direct Registered Offerings In October 2017, the Company entered into Securities Purchase Agreements pursuant to which it sold an aggregate of 8,382,643 shares of common stock for total gross proceeds of $49.9 million, or the October 2017 Direct Registered Offering. The October 2017 Direct Registered Offering was closed on October 25, 2017. In February 2018, the Company entered into a Securities Purchase Agreement pursuant to which it sold (i) 4,090,000 shares of common stock; (ii) 3,000,581 shares of Series A convertible preferred stock and (iii) warrants to purchase 1,418,116 shares of common stock, or the 2018 Offering Warrants for total gross proceeds of $59.1 million, or the March 2018 Direct Registered Offering. The March 2018 Direct Registered Offering was closed on March 5, 2018. The 2018 Offering Warrants have an exercise price of $8.31 per share, became exercisable upon issuance and expire in March 2025. At-The-Market Offering of Common Stock In January 2017, the Company filed a shelf registration statement on Form S-3 with the SEC, which included a base prospectus covering the offering, issuance and sale of up to a maximum aggregate offering of $75.0 million of the Company’s common stock, preferred stock, debt securities, warrants, purchase contracts and/or units and in accordance with Rule 415(a)(4) under the Securities Act FBR acted as sales agent on a best efforts basis and used commercially reasonable efforts to sell on behalf of the Company all of the shares of common stock requested to be sold by the Company, consistent with its normal trading and sales practices, on mutually agreed terms between FBR and the Company. There is no arrangement for funds to be received in any escrow, trust or similar arrangement. In April 2017, the Company agreed to sell up to an additional $25.0 million of the Company’s common stock in accordance with the terms of a sales agreement with FBR and pursuant to an at-the-market offering program in accordance with Rule 415(a)(4) under the Securities Act. FBR is entitled to compensation of up to 3.0% of the gross sales price per share sold. In connection with the sale of the Company’s common stock on the Company’s behalf, FBR is deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of FBR is deemed to be underwriting commissions or discounts. The Company has also agreed to provide indemnification and contribution to FBR with respect to certain liabilities, including liabilities under the Securities Act. In fiscal year 2017, the Company sold an aggregate of 6,575,062 shares of its common stock at an average market price of $6.10 per share, resulting in aggregate gross proceeds of approximately $40.1 million. During the six months ended June 30, 2018, the Company sold an aggregate of 33,097 shares of its common stock at an average market price of $8.41 per share, resulting in aggregate gross proceeds of approximately $0.3 million.

Convertible Preferred Stock

Convertible Preferred Stock	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Convertible Preferred Stock	9. Convertible Preferred Stock In March 2018, the Company issued 3,000,581 shares of Series A convertible preferred stock to an existing investor through the 2018 Direct Registered Offering at a price of $8.31per share (see Note 8). At the date of the financing, because the effective conversion rate of the preferred stock was less than the market value of the Company’s common stock, a beneficial conversion feature of $2.7 million has been recorded as a discount to the convertible preferred stock and an increase to additional paid in capital. Because the preferred stock was perpetual and convertible at the option of the holder at any time, the Company fully amortized the discount related to the beneficial conversion feature as a deemed dividend which was recognized as an increase to accumulated deficit and net loss attributable to common stockholders. Effective on April 19, 2018, all outstanding shares of Series A convertible preferred stock were converted into shares of common stock at a conversion ratio of 1:1. Further, in May 2018, the Company filed a Certificate of Elimination of the Series A Convertible Preferred Stock de-authorizing the 3,000,581 shares of Series A convertible preferred stock. The Company had no outstanding preferred stock as of June 30, 2018.

Warrants

Warrants	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Warrants	10. Warrants Equity Classified Common Stock Warrants In connection with a debt financing in December 2013, the Company issued warrants to purchase 128,231 shares of its common stock with an exercise price of $5.84 per share. These warrants are exercisable any time at the option of the holder until December 16, 2023. None of these warrants had been exercised and they all remained outstanding at June 30, 2018. In connection with the merger of the Company and ViewRay Technologies, Inc. in July 2015, or the Merger, in July and August 2015, the Company conducted a private placement offering during which the Company the five-year anniversary of its date of issuance In connection with the March 2018 Direct Registered Offering, the Company issued warrants to purchase 1,418,116 shares of common stock at an exercise price of $8.31 per share, or the 2018 Offering Warrants. These 2018 Offering Warrants became exercisable upon issuance and expire in March 2025. None of the 2018 Offering Warrants had been exercised and they all remained outstanding at June 30, 2018. As separate classes of securities were issued in a bundled transaction, the gross proceeds from the March 2018 Direct Registered Offering of $59.1 million was allocated to common stock, Series A convertible preferred stock and the 2018 Offering Warrants based on their respective relative fair value upon issuance. The aggregate fair value of the 2018 Offering Warrants of $7.4 million was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions: expected term of seven years, expected volatility of 62.5%, risk-free interest rate of 2.8% and expected dividend yield of 0%. The allocated proceeds from the 2018 Offering Warrants of $6.6 million was recorded in additional paid-in-capital. Liability Classified Common Stock Warrants In connection with the 2016 Private Placement, in August and September 2016, the Company issued warrants, or the 2016 Placement Warrants, that provide the warrant holder the right to purchase 1,380,745 shares of common stock at an exercise price of $2.95 per share. These 2016 Placement Warrants are exercisable at any time at the option of the holder until the seventh anniversary of their date of issuance. The 2016 Placement Warrants also contain protection whereby warrants will expire immediately prior to the consummation of a Change of Control and holders have the right to receive cash in the amount equal to the Black-Scholes value of warrants. A Change of Control is defined as: (i) a merger or consolidation of the Company with another corporation; (ii) the sale, transfer or other disposal of substantially all of the assets or a majority of the Company’s outstanding shares of capital stock; (iii) a purchase or exchange offer accepted by the holders of a majority of the outstanding voting shares of the Company’s capital stock; or (iv) a “person” or “group,” as defined by Section 13(d) and 14(d) of the Securities Exchange Act of 1934, as amended, is or will become the beneficial owner, directly or indirectly, of at least a majority of the voting power of the Company’s capital stock. The 2016 Placement Warrants were accounted for as a liability at the date of issuance and are adjusted to fair value at each balance sheet date, with the change in fair value recorded as a component of other income (expense), net in the condensed consolidated statements of operations. As separate classes of securities were issued in a bundled transaction, the gross proceeds from the 2016 Private Placement of $13.8 million was allocated first to the 2016 Placement Warrants based on its fair value upon issuance, and the residual was allocated to the common stock. The fair value upon issuance of $2.7 million for the 2016 Placement Warrants was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions: expected term of seven years, expected volatility of 61.6%, risk-free interest rate of 1.4% and expected dividend yield of 0%. During the three and six months ended June 30, 2018, the Company recorded a loss of $0.5 million and a gain of $3.1 million, respectively, related to the change in fair value of the 2016 Placement Warrants. During the three and six months ended June 30, 2017, the Company recorded a gain of $2.8 million and a loss of $4.0 million, respectively, related to the change in fair value of the 2016 Placement Warrants. The fair value of the 2016 Placement Warrants of $6.8 million and $9.9 million at June 30, 2018 and December 31, 2017, respectively, was estimated using the Black-Scholes option pricing model and the following weighted-average assumptions: June 30, 2018 December 31, 2017 2016 Placement Warrant: Expected term (in years) 5.2 5.7 Expected volatility 59.8% 62.1% Risk-free interest rate 2.7% 2.2% Expected dividend yield 0% 0% At June 30, 2018, 1,355,641 shares of the 2016 Placement Warrants had not been exercised and were still outstanding. In connection with the 2017 Private Placement, in January 2017, the Company issued warrants, the 2017 Placement Warrants, that provide the warrant holder the right to purchase 1,720,512 shares of common stock at an exercise price of $3.17 per share. These 2017 Placement Warrants became exercisable in July 2017 and expire in January 2024. As separate classes of securities were issued in a bundled transaction, the gross proceeds from the 2017 Private Placement of $26.1 million was allocated first to the 2017 Placement Warrants based on its fair value upon issuance, and the residual was allocated to the common stock. The fair value upon issuance of $3.4 million for the 2017 Placement Warrants was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions: expected term of seven years, expected volatility of 62.9%, risk-free interest rate of 2.2% and expected dividend yield of 0%. During the three and six months ended June 30, 2018, the Company recorded a loss of $0.7 million and a gain of $3.9 million, respectively, related to the change in fair value of the 2017 Placement Warrants. During the three and six months ended June 30, 2017, the Company recorded a gain of $3.4 million and a loss of $5.0 million, respectively, related to the change in fair value of the 2017 Placement Warrants. The fair value of the 2017 Placement Warrants of $8.6 million and $12.5 million at June 30, 2018 and December 31, 2017, respectively, was estimated using the Black-Scholes option pricing model and the following weighted-average assumptions: June 30, 2018 December 31, 2017 2017 Placement Warrant: Expected term (in years) 5.6 6.1 Expected volatility 60.0% 62.3% Risk-free interest rate 2.8% 2.3% Expected dividend yield 0% 0% At June 30, 2018, 1,711,123 shares of the 2017 Placement Warrants had not been exercised and were still outstanding.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	11. Stock-Based Compensation A summary of the Company’s stock option activity and related information is as follows: Options Outstanding Shares Available for Grant Number of Stock Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual (Years) Aggregate Intrinsic Value (In thousands) Balance at December 31, 2017 969,783 8,592,747 $ 3.69 7.4 $ 47,864 Additional options authorized 2,706,158 — Options granted (2,003,229 ) 2,003,229 7.15 Options exercised — (396,939 ) 1.80 Options canceled 155,459 (155,459 ) 5.41 Balance at June 30, 2018 1,828,171 10,043,578 $ 4.43 7.6 $ 25,933 Vested and exercisable at June 30, 2018 5,411,367 $ 3.08 6.4 $ 21,106 Vested and expected to vest at June 30, 2018 9,701,142 $ 4.38 7.6 $ 25,536 The weighted-average grant date fair value of options granted to employees was $4.18 and $3.13 per share during the six months ended June 30, 2018 and 2017, respectively. The grant date fair value of options vested was $2.5 million and $1.9 million during the six months ended June 30, 2018 and 2017, respectively. Aggregate intrinsic value represents the difference between the estimated fair value of the underlying common stock and the exercise price of outstanding, in-the-money options. The aggregate intrinsic value of options exercised was $2.2 million and $1.5 million during the six months ended June 30, 2018 and 2017, respectively. At June 30, 2018, total unrecognized compensation cost related to stock-based awards granted to employees, net of estimated forfeitures, was $14.8 million which is expected to be recognized over a weighted-average period of 3.0 years. Determination of Fair Value The determination of the fair value of stock options on the date of grant using an option-pricing model is affected by the estimated fair value of the Company’s common stock, as well as assumptions regarding a number of complex and subjective variables. The variables used to calculate the fair value of stock options using the Black-Scholes option-pricing model include actual and projected employee stock option exercise behaviors, expected price volatility of the Company’s common stock, the risk-free interest rate and expected dividends. Each of these inputs is subjective and generally requires significant judgment to determine. Fair Value of Common Stock Beginning March 31, 2016, the Company’s common stock shares were listed on The NASDAQ Global Market, or NASDAQ. Fair value of the common stock is the adjusted closing price of the Company’s common stock on the trading date on these stock exchanges. Expected Term The expected term represents the period that the Company’s option awards are expected to be outstanding. The Company considers several factors in estimating the expected term of options granted, including the expected lives used by a peer group of companies within the Company’s industry that the Company considers to be comparable to its business and the historical option exercise behavior of its employees, which the Company believes is representative of future behavior. Expected Volatility As the Company has a limited trading history for its common stock, the expected stock price volatility for the Company’s common stock was estimated by taking a combination of the average historic price volatility of the Company’s common stock and industry peers based on daily price observations over a period equivalent to the expected term of the stock option grants. Industry peers consist of several public companies in the Company’s industry which were the same as the comparable companies used in the common stock valuation analysis. The Company intends to continue to consistently apply this process using the same or similar public companies until a sufficient amount of historical information regarding the volatility of its own share price becomes available, or unless circumstances change such that the identified companies are no longer similar to the Company, in which case, more suitable companies whose share prices are publicly available would be used in the calculation. Risk-Free Interest Rate The risk-free interest rate is based on the zero-coupon U.S. Treasury notes, with maturities similar to the expected term of the options. Expected Dividend Yield The Company does not anticipate paying any dividends in the foreseeable future and, therefore, uses an expected dividend yield of zero in the Black-Scholes option-valuation model. In addition to the Black-Scholes assumptions discussed immediately above, the estimated forfeiture rate also has a significant impact on the related stock-based compensation. The forfeiture rate of stock options is estimated at the time of grant and revised in subsequent periods if actual forfeitures differ from those estimates. The Company uses historical data to estimate pre-vesting option forfeitures and records stock-based compensation expense only for those awards that are expected to vest. The fair value of employee stock option was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions: Six Months Ended June 30, 2018 2017 Expected term (in years) 6.0 6.0 Expected volatility% 61.2% 67.1% Risk-free interest rate% 2.8% 2.1% Expected dividend yield% 0.0% 0.0% Restricted Stock Units From time to time, the Company grants Restricted Stock Units, or RSUs, to its board of directors for their services. These RSUs were fully vested upon issuance and will be released and settled upon termination of the board services or the occurrence of a change in control event. The fair value of RSUs is based on the closing market price of the Company’s common stock on the grant date. In September 2016 and November 2017, the Company granted 112,578 shares and 43,554 shares of RSUs, to its board members and these RSUs had a grant-date fair value of $3.58 and released in December 2017 in connection with the resignation of one board member. In connection with the departure of two board members in June 2018, 34,502 shares of RSUs with a grant date fair value of $3.58 per share and 12,467 shares of RSUs with a grant date fair value of $8.02 per share are expected to be released in the third quarter of fiscal 2018. In November 2017, the Company granted 12,468 shares of RSUs with a grant-date fair value of $8.02 per share to one executive officer upon his termination. These RSUs were fully vested upon issuance and were released in the first quarter of fiscal 2018. For the six months ended June 30, 2018 and 2017, no RSUs were issued and no stock-based compensation expense related to RSUs was recorded in the accompanying condensed consolidated statements of operations. Stock-Based Compensation Expense Total stock-based compensation expense recognized in the Company’s condensed consolidated statements of operations is classified as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Research and development $ 347 $ 216 $ 550 $ 381 Selling and marketing 194 72 321 123 General and administrative 1,142 725 2,002 1,278 Total stock-based compensation expense $ 1,683 $ 1,013 $ 2,873 $ 1,782 During the three and six months ended June 30, 2018 and 2017, there were no stock-based compensation expenses capitalized as a component of inventory or recognized in cost of revenue. Stock-based compensation relating to stock-based awards granted to consultants were insignificant during the three and six months ended June 30, 2018 and 2017.

Income Tax

Income Tax	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Tax	12. Income Tax The Tax Cuts and Jobs Act, or the 2017 Tax Act, was enacted on December 22, 2017. Among various provisions, the 2017 Tax Act reduces the U.S. federal corporate tax rate from 35% to 21%. The Company recognized the income tax effects of the 2017 Tax Act in its 2017 financial statements in accordance with SEC Staff Accounting Bulletin No. 118 (“SAB 118”), which provides guidance for the application of ASC Topic 740, Income Taxes, in the reporting period in which the 2017 Tax Act was signed into law. As such, the Company’s 2017 financial results reflected the income tax effects of the 2017 Tax Act for which the accounting under ASC Topic 740 was complete and provisional amounts for those specific income tax effects of the 2017 Tax Act for which the accounting under ASC Topic 740 was incomplete, but a reasonable estimate could be determined. Upon completion of our 2017 U.S. income tax return in the current year, we may identify additional remeasurement adjustments to our recorded deferred tax assets. We will continue to assess our provision for income taxes as future guidance is issued, but do not currently anticipate significant revisions will be necessary. Any such revisions will be treated in accordance with the measurement period guidance outlined in SAB 118. For the quarter ended June 30, 2018, we have not made any adjustments to the provisional amounts recorded at December 31, 2017. Due to the current operating losses, the Company recorded zero income tax expense during the six months ended June 30, 2018 and 2017, respectively. During these periods, the Company’s activities were limited to U.S. federal and state tax jurisdictions, as it does not have any foreign operations. The federal and state effective tax rate is approximately 22%. Due to the Company’s history of cumulative losses, management concluded that, after considering all the available objective evidence, it is not more likely than not that all of the Company’s net deferred tax assets will be realized. Accordingly, the Company’s deferred tax assets, which includes net operating loss, or NOL, carryforwards and tax credits related primarily to research and development continue to be subject to a valuation allowance as of June 30, 2018. The Company expects to continue to maintain a full valuation allowance until there is sufficient evidence to support recoverability of its deferred tax assets. The Company had unrecognized tax benefits of $1.3 million and $1.1 million at June 30, 2018 and December 31, 2017, respectively. The reversal of the uncertain tax benefits would not affect the effective tax rate to the extent that the Company continues to maintain a full valuation allowance against its deferred tax assets. Unrecognized tax benefits may change during the next 12 months for items that arise in the ordinary course of business. Interest and/or penalties related to income tax matters are recognized as a component of income tax expense. At June 30, 2018, and December 31, 2017, there were no accrued interest and penalties related to uncertain tax positions.

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Loss per Share	13. Net Loss per Share Since the Company was in a loss position for all periods presented, diluted net loss per common share is the same as basic net loss per common share for all periods presented, because the inclusion of all potential common shares outstanding would have an anti-dilutive effect. The following weighted-average common stock equivalents were excluded from the calculation of diluted net loss per share for the periods presented, because including them would have an anti-dilutive effect: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Series A convertible preferred stock (if converted) 593,522 — 746,001 — Options to purchase common stock 9,714,129 8,006,323 9,157,418 7,561,888 Common stock warrants 4,811,629 3,428,248 4,315,410 3,266,653 Restricted stock units 134,587 110,494 135,878 111,530 Total 15,253,867 11,545,065 14,354,707 10,940,071

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	14. Related Party Transactions In December 2004, the Company entered into a licensing agreement with the University of Florida Research Foundation, or UFRF, whereby UFRF granted the Company a worldwide exclusive license to certain of UFRF’s patents in exchange for 33,652 shares of common stock and a 1% royalty, with a minimum $50,000 royalty payment per quarter, from sales of products developed and sold by the Company utilizing the licensed patents. In January 2017, the Company entered into a sales consulting agreement with Puissance Capital Management, or PCM, to assist with business development activities in a key market in Asia. PCM is the investment manager of Puissance Cross Board Opportunities LLP, a stockholder in the Company. Theodore T. Wang, Ph.D., a member of the Company’s board of directors, is the managing member of the general partners of PCM. The sales consulting agreement has a term of one year with a total consideration of $1.3 million. This amount has been fully expensed in the first quarter of 2018.

Summary of Significant Accoun20

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States, or GAAP, and pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC. The condensed consolidated financial statements include the accounts of ViewRay, Inc. and its wholly owned subsidiary, ViewRay Technologies, Inc. All inter-company accounts and transactions have been eliminated in consolidation. In the opinion of management, all adjustments, including normal recurring adjustments, considered necessary for a fair presentation of the Company’s unaudited condensed consolidated financial statements, have been included. The results of operations for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 or any future period. These unaudited condensed consolidated financial statements and their notes should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2017. Effective January 1, 2018, the Company adopted Accounting Standard Codification Topic 606, or ASC 606, Revenues from Contracts with Customers,
Significant Accounting Policies	Significant Accounting Policies The significant accounting policies used in preparation of these condensed consolidated financial statements are disclosed in the notes to consolidated financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 filed with the SEC on March 12, 2018, and have not changed significantly since that filing, except for the impact of the adoption of the new accounting guidance related to revenue recognition. Revenue Recognition The Company derives revenues primarily from the sale of MRIdian systems and related services as well as support and maintenance services on sold systems. The Company accounts for revenue contracts with customers by applying the requirements of ASC 606, which includes the following steps: • Identification of the contract, or contracts, with a customer; • Identification of the performance obligations in the contract; • Determination of the transaction price; • Allocation of the transaction price to the performance obligations in the contract; and • Recognition of revenue when, or as, the Company satisfies a performance obligation. In all sales arrangements, revenues are recognized when control of the promised goods or services are transferred to customers, in an amount that reflects the consideration the Company expects to be entitled to receive in exchange for those goods or services. For sales of MRIdian systems that the Company is required to install at the customer site, product revenue is recognized upon receipt of customer acceptance. For sales of MRIdian systems for which the Company is not responsible for installing, product revenue is recognized when the entire system is delivered and control of the system is transferred to the customer. For sales of the related support and maintenance services, a time-elapsed method is used to measure progress toward complete satisfaction of performance obligations and service revenue is recognized ratably over the service contract term, which is typically 12 months. Arrangements with Multiple Performance Obligation The Company frequently enters into sales arrangements that include multiple performance obligations, which mainly consist of (i) sale of MRIdian systems, which generally includes installation and embedded software, and (ii) product support, which includes extended service and maintenance. For such arrangements, the Company allocates revenue to each performance obligation based on its relative standalone selling price. The standalone selling price, or SSP, is determined based on observable prices at which the Company separately sells the products and services. If an SSP is not directly observable, the Company will estimate the SSP considering market conditions or internally approved pricing guidelines related to the performance obligations. Product Revenue Product revenue is derived primarily from the sales of MRIdian system. The system contains both software and non-software components that together deliver essential functionality. The Company’s customer contracts generally call for on-site assembly of the system components and system integration. Once the system installation is completed, the Company performs a detailed demonstration with the customer showing that the MRIdian system meets the standard product specifications. After successful demonstration, the customer signs a document indicating customer’s acceptance. For sales of MRIdian systems that the Company is required to install at the customer site, revenue recognition occurs when the customer acknowledges that the system operates in accordance with standard product specifications, the customer accepts the installed unit by signing the acceptance document and the control of the system is transferred to the customer. Certain customer contracts with distributors do not require ViewRay installation at the customer site, and the distributors typically have their own or engage a qualifying third-party certified technician to perform the installation. For sales of MRIdian systems for which the Company is not responsible for installation, revenue recognition occurs when the entire system is delivered, and the control of the system is transferred to the customer. Service Revenue Service revenue is derived primarily from maintenance services. The maintenance and support service is a stand-ready obligation which is performed over the term of the arrangement and, as a result, service revenue is recognized ratably over the service period as the customers benefit from the service throughout the service period. Distribution Rights Revenue In December 2014, the Company entered into a distribution agreement with Itochu Corporation pursuant to which it appointed Itochu as its exclusive distributor for the promotion, sale and delivery of MRIdian products within Japan. In consideration of the exclusive distribution rights granted, the Company received $4.0 million, which was recorded as deferred revenue. Starting in August 2016, distribution rights revenue is recognized ratably over the remaining term of the distribution agreement of approximately 8.5 years . The following table presents revenue disaggregated by types and geography (in thousands): Three Months Ended June 30, Six Months Ended June 30, U.S. 2018 2017 2018 2017 Product $ 6,053 $ — $ 19,588 $ — Service 502 312 898 1,191 Total U.S. revenue $ 6,555 $ 312 $ 20,486 $ 1,191 Outside of U.S. ("OUS") Product $ 9,313 $ — $ 21,157 $ — Service 456 267 752 496 Distribution rights 119 119 238 238 Total OUS revenue $ 9,888 $ 386 $ 22,147 $ 734 Total Product $ 15,366 $ — $ 40,745 $ — Service 958 579 1,650 1,687 Distribution rights 119 119 238 238 Total revenue $ 16,443 $ 698 $ 42,633 $ 1,925 Contract Balances The timing of revenue recognition, billings and cash collections results in short-term and long-term trade receivables, customer deposit, deferred revenues and deferred cost of revenue on the condensed consolidated balance sheets. Trade receivables are recorded at the original invoiced amount, net of an estimated allowance for doubtful accounts. Trade credit is generally extended on a short-term basis. The Company occasionally provides for long-term trade credit for its maintenance services so that the period between when the services are rendered to its customers and when the customers pay for that service is within one year. Thus, the Company’s trade receivables do not bear interest or contain significant financing component. Long-term trade receivables of $400 thousand are reported within other assets in the condensed consolidated balance sheets at June 30, 2018. These amounts are billed in accordance with the terms of the customer contracts to which they relate and are expected to be collected three to four years from the date of invoice as the underlying maintenance services are rendered. The Company had no long-term trade receivables at December 31, 2017. Trade receivables are periodically evaluated for collectability based on past credit history with customers and their current financial condition. Changes in the estimated collectability of trade receivables are recorded in the results of operations for the period in which the estimate is revised. Trade receivables that are deemed uncollectible are offset against the allowance for doubtful accounts. The Company generally does not require collateral for trade receivables. Based on the specific customers and the current economic conditions, there was no allowance for doubtful accounts recorded at June 30, 2018 or December 31, 2017. Customer deposits represent payments received in advance of system installation. For domestic and international sales, advance payments received prior to inventory shipments and customer acceptance are recorded as customer deposits. Advance payments are subsequently reclassified to deferred revenue upon inventory shipment when the title and risk of loss of inventory items transfer to customers. All customer deposits, including those that are expected to be a deposit for more than one year, are classified as current liabilities based on consideration of the Company’s normal operating cycle (the time between acquisition of the inventory components and the final cash collection from customers on these inventory components) which is in excess of one year. Deferred revenue consists of deferred product revenue and deferred service revenue. Deferred product revenue arises from timing differences between the fulfillment of contract obligations and satisfaction of all revenue recognition criteria consistent with the Company’s revenue recognition policy. Deferred service revenue results from the advance billing for services to be delivered over a period of time. Deferred revenues expected to be realized within one year or normal operating cycle are classified as current liabilities. Deferred cost of revenue consists of cost for inventory items that have been shipped with title and risk of loss transferred to the customer, but the customer acceptance has not been received. Deferred cost of revenue is included as part of current assets as the corresponding deferred product revenue is expected to be realized within one year or normal operating cycle. During the three and six months ended June 30, 2018, the Company recognized $6.8 million and $17.9 million revenue that was included in the deferred revenue balance at the beginning of each reporting period. During the three and six months ended June 30, 2017, the Company recognized $673.7 thousand and $735.5 thousand revenue that was included in the deferred revenue balance at the beginning of each reporting period. Practical Expedients Election As part of the Company's adoption of ASC 606, the Company elected to use the practical expedient to expense costs to obtain a contract as incurred when the amortization period would have been one year or less, which mainly includes the Company's internal sales force compensation program.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, FASB, issued ASU No. 2016-02, Leases (Topic 842) In June 2018, the FASB issued ASU No. 2018-07 Compensation — Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In May 2014, the FASB issued ASC 606. Under the standard, revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration the entity expects to receive in exchange for those goods or services. Effective January 1, 2018, the Company adopted the requirements of ASC 606 using the full retrospective method. The adoption has no impact on the prior period financial statements, and the related disclosures required by the new standard have been updated in the “Significant Accounting Policies” section above. On January 1, 2018, the Company adopted ASU No.2016-15 , Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments Statement of Cash Flows (Topic 230): Restricted Cash Under ASU 2016-18, restricted cash and restricted cash equivalent amounts are presented along with cash and cash equivalents when reconciling the total beginning and ending amounts shown on the statement of cash flows. The Company reflected the impact of ASU No. 2016-18 to the comparative prior period which resulted in an increase in the beginning and ending cash, cash equivalents and restricted cash of $ In May 2017, the FASB issued ASU No. 2017-09 , Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting In the first quarter of 2018, the Company adopted ASU No. 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118,

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Schedule of Revenue Disaggregated by Types and Geography	The following table presents revenue disaggregated by types and geography (in thousands): Three Months Ended June 30, Six Months Ended June 30, U.S. 2018 2017 2018 2017 Product $ 6,053 $ — $ 19,588 $ — Service 502 312 898 1,191 Total U.S. revenue $ 6,555 $ 312 $ 20,486 $ 1,191 Outside of U.S. ("OUS") Product $ 9,313 $ — $ 21,157 $ — Service 456 267 752 496 Distribution rights 119 119 238 238 Total OUS revenue $ 9,888 $ 386 $ 22,147 $ 734 Total Product $ 15,366 $ — $ 40,745 $ — Service 958 579 1,650 1,687 Distribution rights 119 119 238 238 Total revenue $ 16,443 $ 698 $ 42,633 $ 1,925

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2018
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands): June 30, 2018 December 31, 2017 Prototype $ 12,622 $ 11,929 Machinery and equipment 10,732 7,831 Leasehold improvements 4,327 4,438 Software 1,228 1,142 Furniture and fixtures 588 558 Property and equipment, gross 29,497 25,898 Less: accumulated depreciation and amortization (15,910 ) (14,334 ) Property and equipment, net $ 13,587 $ 11,564
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): June 30, 2018 December 31, 2017 Accrued payroll and related benefits $ 4,049 $ 3,944 Accrued accounts payable 1,625 2,671 Sales and other tax payable 1,607 149 Accrued legal, accounting and professional fees 313 322 Other 56 121 Total accrued liabilities $ 7,650 $ 7,207
Schedule of Deferred Revenue	Deferred revenue consisted of the following (in thousands): June 30, 2018 December 31, 2017 Deferred revenue: Product $ 11,917 $ 18,861 Services 4,908 1,182 Distribution rights 3,108 3,346 Total deferred revenue 19,933 23,389 Less: current portion of deferred revenue (15,540 ) (20,151 ) Noncurrent portion of deferred revenue $ 4,393 $ 3,238
Schedule of Other Long Term Liabilities	Other Long-Term Liabilities June 30, 2018 December 31, 2017 Accrued interest, noncurrent portion $ 7,894 $ 6,218 Deferred rent, noncurrent portion 378 167 Other 828 985 Total other-long term liabilities $ 9,100 $ 7,370

Fair Value of Financial Instr23

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Financial Liabilities	The following table sets forth the fair value of the Company’s financial liabilities by level within the fair value hierarchy (in thousands): At June 30, 2018 Level 1 Level 2 Level 3 Total 2017 Placement Warrants Liability $ — $ — $ 8,582 $ 8,582 2016 Placement Warrants Liability — — 6,829 6,829 Total $ — $ — $ 15,411 $ 15,411 At December 31, 2017 Level 1 Level 2 Level 3 Total 2017 Placement Warrants Liability $ — $ — $ 12,487 $ 12,487 2016 Placement Warrants Liability — — 9,933 9,933 Total $ — $ — $ 22,420 $ 22,420
Summary of Changes in Fair Value of Level 3 Financial Liabilities	The following table sets forth a summary of the changes in fair value of the Company’s Level 3 financial liabilities (in thousands): Six Months Ended June 30, 2018 2017 Fair value, beginning of period $ 22,420 $ 2,723 Issuance of 2017 Placement Warrants — 3,373 Change in fair value of Level 3 financial liabilities (7,009 ) 9,032 Fair value, end of period $ 15,411 $ 15,128

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments Under Noncancelable Operating Lease Agreements	At June 30, 2018, the future minimum payments for the operating leases are as follows (in thousands): Year Ending December 31, Future Payments The remainder of 2018 $ 746 2019 2,039 2020 2,321 2021 2,391 2022 2,463 Thereafter 6,709 Total future minimum payments $ 16,669

Warrants (Tables)

Warrants (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Summary of Assumptions using Black- Scholes Option Pricing Model to estimate fair value	The fair value of the 2016 Placement Warrants of $6.8 million and $9.9 million at June 30, 2018 and December 31, 2017, respectively, was estimated using the Black-Scholes option pricing model and the following weighted-average assumptions: June 30, 2018 December 31, 2017 2016 Placement Warrant: Expected term (in years) 5.2 5.7 Expected volatility 59.8% 62.1% Risk-free interest rate 2.7% 2.2% Expected dividend yield 0% 0% The fair value of the 2017 Placement Warrants of $8.6 million and $12.5 million at June 30, 2018 and December 31, 2017, respectively, was estimated using the Black-Scholes option pricing model and the following weighted-average assumptions: June 30, 2018 December 31, 2017 2017 Placement Warrant: Expected term (in years) 5.6 6.1 Expected volatility 60.0% 62.3% Risk-free interest rate 2.8% 2.3% Expected dividend yield 0% 0%

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Company's Stock Option Activity and Related Information	A summary of the Company’s stock option activity and related information is as follows: Options Outstanding Shares Available for Grant Number of Stock Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual (Years) Aggregate Intrinsic Value (In thousands) Balance at December 31, 2017 969,783 8,592,747 $ 3.69 7.4 $ 47,864 Additional options authorized 2,706,158 — Options granted (2,003,229 ) 2,003,229 7.15 Options exercised — (396,939 ) 1.80 Options canceled 155,459 (155,459 ) 5.41 Balance at June 30, 2018 1,828,171 10,043,578 $ 4.43 7.6 $ 25,933 Vested and exercisable at June 30, 2018 5,411,367 $ 3.08 6.4 $ 21,106 Vested and expected to vest at June 30, 2018 9,701,142 $ 4.38 7.6 $ 25,536
Schedule of Weighted-Average Assumptions Used in Black-Scholes Option-Pricing Model to Estimate Fair Value of Employee Stock Option at Grant Date	The fair value of employee stock option was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions: Six Months Ended June 30, 2018 2017 Expected term (in years) 6.0 6.0 Expected volatility% 61.2% 67.1% Risk-free interest rate% 2.8% 2.1% Expected dividend yield% 0.0% 0.0%
Summary of Stock-Based Compensation Expense	Total stock-based compensation expense recognized in the Company’s condensed consolidated statements of operations is classified as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Research and development $ 347 $ 216 $ 550 $ 381 Selling and marketing 194 72 321 123 General and administrative 1,142 725 2,002 1,278 Total stock-based compensation expense $ 1,683 $ 1,013 $ 2,873 $ 1,782

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	Since the Company was in a loss position for all periods presented, diluted net loss per common share is the same as basic net loss per common share for all periods presented, because the inclusion of all potential common shares outstanding would have an anti-dilutive effect. The following weighted-average common stock equivalents were excluded from the calculation of diluted net loss per share for the periods presented, because including them would have an anti-dilutive effect: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Series A convertible preferred stock (if converted) 593,522 — 746,001 — Options to purchase common stock 9,714,129 8,006,323 9,157,418 7,561,888 Common stock warrants 4,811,629 3,428,248 4,315,410 3,266,653 Restricted stock units 134,587 110,494 135,878 111,530 Total 15,253,867 11,545,065 14,354,707 10,940,071

Background and Organization - A

Background and Organization - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net loss	$ (21,990)	$ (8,353)	$ (26,804)	$ (36,314)
Net cash used from operations			(48,838)	$ (23,883)
Cash and cash equivalents	$ 66,143		$ 66,143		$ 57,389

Summary of Significant Accoun29

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	Aug. 31, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Long-term trade receivables		$ 400,000		$ 400,000			$ 0
Long-term trade credit maintenance services term				1 year
Allowance for doubtful accounts		0		$ 0			$ 0
Deferred revenue, recognized		6,800,000	$ 673,700	17,900,000	$ 735,500
Operating leases future minimum payments due		$ 16,669,000		$ 16,669,000
ASU No. 2016-18
Significant Accounting Policies [Line Items]
Increase in cash, cash equivalents and restricted cash						$ 1,100,000
Minimum
Significant Accounting Policies [Line Items]
Expected long-term trade receivables collection period				3 years
Maximum
Significant Accounting Policies [Line Items]
Expected long-term trade receivables collection period				4 years
Itochu Corporation Agreement
Significant Accounting Policies [Line Items]
Remaining term of distribution agreement	8 years 6 months	8 years 6 months		8 years 6 months
Itochu Corporation Agreement | Distribution Rights
Significant Accounting Policies [Line Items]
Distribution revenue reclassified as deferred revenue	$ 4,000,000	$ 4,000,000		$ 4,000,000

Summary of Significant Accoun30

Summary of Significant Accounting Policies - Summary of Revenue Disaggregated by Types and Geography (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	$ 16,443	$ 698	$ 42,633	$ 1,925
Product
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	15,366	0	40,745	0
Service
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	958	579	1,650	1,687
Distribution Rights
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	119	119	238	238
U.S.
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	6,555	312	20,486	1,191
U.S. | Product
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	6,053	0	19,588	0
U.S. | Service
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	502	312	898	1,191
Outside of U.S. ("OUS")
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	9,888	386	22,147	734
Outside of U.S. ("OUS") | Product
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	9,313	0	21,157	0
Outside of U.S. ("OUS") | Service
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	456	267	752	496
Outside of U.S. ("OUS") | Distribution Rights
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	$ 119	$ 119	$ 238	$ 238

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 29,497	$ 25,898
Less: accumulated depreciation and amortization	(15,910)	(14,334)
Property and equipment, net	13,587	11,564
Prototype
Property Plant And Equipment [Line Items]
Property and equipment, gross	12,622	11,929
Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	10,732	7,831
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	4,327	4,438
Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,228	1,142
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 588	$ 558

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization	$ 923	$ 532	$ 1,600	$ 994

Balance Sheet Components - Sc33

Balance Sheet Components - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued payroll and related benefits	$ 4,049	$ 3,944
Accrued accounts payable	1,625	2,671
Sales and other tax payable	1,607	149
Accrued legal, accounting and professional fees	313	322
Other	56	121
Total accrued liabilities	$ 7,650	$ 7,207

Balance Sheet Components - Sc34

Balance Sheet Components - Schedule of Deferred Revenue (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Deferred Revenue [Line Items]
Total deferred revenue	$ 19,933	$ 23,389
Less: current portion of deferred revenue	(15,540)	(20,151)
Noncurrent portion of deferred revenue	4,393	3,238
Product
Deferred Revenue [Line Items]
Total deferred revenue	11,917	18,861
Services
Deferred Revenue [Line Items]
Total deferred revenue	4,908	1,182
Distribution Rights
Deferred Revenue [Line Items]
Total deferred revenue	$ 3,108	$ 3,346

Balance Sheet Components - Sc35

Balance Sheet Components - Schedule of Other Long Term Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued interest, noncurrent portion	$ 7,894	$ 6,218
Deferred rent, noncurrent portion	378	167
Other	828	985
Total other-long term liabilities	$ 9,100	$ 7,370

Fair Value of Financial Instr36

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Change in fair value of Level 3 financial liabilities			$ (7,009,000)	$ 9,032,000
Two Thousand Sixteen And Two Thousand Seventeen Private Placement Warrants
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Change in fair value of Level 3 financial liabilities	$ (1,200,000)	$ 6,200,000	7,000,000	$ (9,000,000)
Transfers between Level 1 to Level 2	0		0
Transfers between Level 2 to Level 1	0		$ 0
Transfers into or out of Level 3	$ 0

Fair Value of Financial Instr37

Fair Value of Financial Instruments - Schedule of Fair Value of Financial Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	$ 15,411	$ 22,420
Fair Value Measurement on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	15,411	22,420
Fair Value Measurement on Recurring Basis | 2017 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	8,582	12,487
Fair Value Measurement on Recurring Basis | 2016 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	6,829	9,933
Level 1 | Fair Value Measurement on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	0	0
Level 1 | Fair Value Measurement on Recurring Basis | 2017 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	0	0
Level 1 | Fair Value Measurement on Recurring Basis | 2016 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	0	0
Level 2 | Fair Value Measurement on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	0	0
Level 2 | Fair Value Measurement on Recurring Basis | 2017 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	0	0
Level 2 | Fair Value Measurement on Recurring Basis | 2016 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	0	0
Level 3 | Fair Value Measurement on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	15,411	22,420
Level 3 | Fair Value Measurement on Recurring Basis | 2017 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	8,582	12,487
Level 3 | Fair Value Measurement on Recurring Basis | 2016 Placement Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Placement Warrants Liability	$ 6,829	$ 9,933

Fair Value of Financial Instr38

Fair Value of Financial Instruments - Summary of Changes in Fair Value of Level 3 Financial Liabilities (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value, beginning of period	$ 22,420	$ 2,723
Change in fair value of Level 3 financial liabilities	(7,009)	9,032
Fair value, end of period	15,411	15,128
2017 Placement Warrants
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Issuance of Placement Warrants	$ 0	$ 3,373

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	Mar. 31, 2016	Jun. 26, 2015	Oct. 31, 2017	Apr. 30, 2017	May 31, 2016	Jun. 30, 2018
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 50,000,000
Current borrowing capacity	$ 15,000,000	30,000,000	$ 15,000,000	$ 5,000,000
Remaining borrowing capacity	20,000,000	20,000,000
Proceeds from initial public offering		40,000,000
Post Money Valuation Minimum Amount		120,000,000
Debt drawn		$ 30,000,000	$ 0		$ 15,000,000
Debt maturity date						Jun. 26, 2020
Interest payment end date						Mar. 31, 2020
Frequency of periodic payment						quarterly
Debt instrument cash interest rate percentage		12.50%
Debt instrument cash interest rate percentage		8.00%
Deferred payment in-kind interest rate		4.50%
Facility fee		7.00%
Term loan first amendment description						In March 2016, the Company and CRG executed an amendment to the original terms of the CRG Term Loan such that, with regard to the conditions for borrowing the remaining $20.0 million available under the CRG Term Loan, the Company may, at its election, draw down (i) an amount of either $10.0 million or $15.0 million in up to two advances upon achievement of a minimum of $15.0 million of aggregate product and service revenue during any consecutive 12 month period ending on or before March 31, 2016 and (ii) an additional $5.0 million (or $10.0 million, if the previous draw made was only in an amount of $10.0 million) upon achievement of a minimum of $25.0 million of aggregate product and service revenue during any consecutive 12 month period ending on or before December 31, 2016 and upon execution of the first sales contract of the Company?s second generation product.
Term loan second amendment description						In April 2017, the Company and CRG executed an amendment to the terms of its CRG Term Loan. Amendments to the CRG Term Loan include availability of the existing $5.0 million tranche at ViewRay’s option through June 30, 2017, the addition of a $15.0 million tranche of borrowing capacity available at ViewRay’s option through September 30, 2017, extension of the interest-only and payment in-kind period, a decrease to the combined 2016 and 2017 revenue covenant and a 1.75% increase to the facility fee
Additional borrowing capacity				$ 15,000,000
Existing capacity extended expiration date			Dec. 31, 2017	Jun. 30, 2017
Additional capacity extended expiration date				Sep. 30, 2017
Increase in facility fee				1.75%
Term loan third amendment description						In October 2017, the Company and CRG executed another amendment to the terms of its CRG Term Loan, as amended in March 2016 and April 2017. This amendment extended the availability of the existing $15.0 million borrowing capacity through December 31, 2017.
Term loan fourth amendment description						In February 2018, the Company and CRG executed an amendment to the terms of its CRG Term Loan to decrease the amount of the minimum combined 2016 and 2017 revenue covenant.
Amount outstanding under the agreement						$ 45,000,000
Deferred payment in-kind interest						$ 5,900,000
Milestone One
Debt Instrument [Line Items]
Remaining borrowing capacity	10,000,000
Required minimum gross revenue	15,000,000
Milestone One | Maximum
Debt Instrument [Line Items]
Remaining borrowing capacity	15,000,000
Debt drawn	15,000,000
Milestone One | Minimum
Debt Instrument [Line Items]
Debt drawn	10,000,000
Milestone Two
Debt Instrument [Line Items]
Remaining borrowing capacity	5,000,000
Required minimum gross revenue	25,000,000
Debt drawn	15,000,000
Milestone Two | Maximum
Debt Instrument [Line Items]
Remaining borrowing capacity	$ 10,000,000
First 12 Months
Debt Instrument [Line Items]
Prepayment penalty		3.00%
After Year 1 but on or Before Year 2
Debt Instrument [Line Items]
Prepayment penalty		2.00%
After Year 2 but on or Before Year 3
Debt Instrument [Line Items]
Prepayment penalty		1.00%
After Year 3 Thereafter Until Maturity
Debt Instrument [Line Items]
Prepayment penalty		0.00%
MRIdian System
Debt Instrument [Line Items]
Required minimum gross revenue		$ 25,000,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	1 Months Ended
	Jun. 30, 2018	Apr. 30, 2018	Dec. 31, 2017
Operating Leased Assets [Line Items]
Purchase commitments	$ 0		$ 0
Lease Agreement | Mountain View, California
Operating Leased Assets [Line Items]
Lease agreement, term of contract		7 years
Lease agreement, renewal term	68 months
Lease agreement, expiration date	Jul. 31, 2025
Lease Agreement | Mountain View, California | Maximum
Operating Leased Assets [Line Items]
Lease agreement, renewal term		5 years

Commitments and Contingencies41

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Noncancelable Operating Lease Agreements (Detail) $ in Thousands	Jun. 30, 2018USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
The remainder of 2018	$ 746
2,019	2,039
2,020	2,321
2,021	2,391
2,022	2,463
Thereafter	6,709
Total future minimum payments	$ 16,669

Distribution Agreement - Additi

Distribution Agreement - Additional Information (Detail) $ in Thousands	Aug. 31, 2016USD ($)	Aug. 31, 2016USD ($)	Dec. 31, 2014USD ($)Installment	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)
Marketing Agreement [Line Items]
Distribution fee reclassified to deferred revenue				$ 19,933		$ 19,933			$ 23,389
Distribution Rights
Marketing Agreement [Line Items]
Distribution fee reclassified to deferred revenue				$ 3,108		$ 3,108			$ 3,346
Itochu Corporation Agreement
Marketing Agreement [Line Items]
Distribution agreement term			10 years
Number of installments | Installment			3
Remaining term of distribution agreement	8 years 6 months			8 years 6 months		8 years 6 months
Distribution rights revenue				$ 119	$ 119	$ 238	$ 238
Itochu Corporation Agreement | Distribution Rights
Marketing Agreement [Line Items]
Distribution fees			$ 4,000
Distribution fee reclassified to deferred revenue	$ 4,000	$ 4,000
Itochu Corporation Agreement | First Installment | Distribution Rights
Marketing Agreement [Line Items]
Distribution fees			1,000
Itochu Corporation Agreement | Second Installment | Distribution Rights
Marketing Agreement [Line Items]
Distribution fees			1,000
Itochu Corporation Agreement | Third Installment
Marketing Agreement [Line Items]
Distribution fees payment		$ 2,000
Itochu Corporation Agreement | Third Installment | Distribution Rights
Marketing Agreement [Line Items]
Distribution fees			$ 2,000
Itochu Corporation Agreement | First and Second Installment
Marketing Agreement [Line Items]
Distribution fees payment								$ 2,000

Equity Financing - Additional I

Equity Financing - Additional Information (Detail) - USD ($)	1 Months Ended					6 Months Ended		12 Months Ended
	Feb. 28, 2018	Oct. 31, 2017	Jan. 31, 2017	Sep. 30, 2016	Aug. 31, 2016	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Apr. 30, 2017
2016 Placement Warrants
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase common stock, shares				1,380,745	1,380,745
Warrant exercise price				$ 2.95	$ 2.95
Warrant expiration period				7 years	7 years
2017 Placement Warrants
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase common stock, shares			1,720,512
Warrant exercise price			$ 3.17
Proceed from private placement and equity issuances, gross			$ 26,100,000
Warrant exercisable date			Jul. 31, 2017
Warrant expiration date			Jan. 31, 2024
At The Market Offering Program
Subsidiary Sale Of Stock [Line Items]
Aggregate gross proceeds from issuance of common stock						$ 278,000	$ 39,524,000	$ 40,100,000
Compensation percentage pertaining to gross sales price per share sold						3.00%
Average market price per share						$ 8.41		$ 6.10
At The Market Offering Program | Maximum
Subsidiary Sale Of Stock [Line Items]
Maximum aggregate offering price			$ 75,000,000
Maximum common stock saleable shares, value			$ 25,000,000						$ 25,000,000
At The Market Offering Program | Common Stock
Subsidiary Sale Of Stock [Line Items]
Stock issued during period						33,097		6,575,062
2016 Private Placement | Common Stock
Subsidiary Sale Of Stock [Line Items]
Private placement, common shares				4,602,506
Proceed from private placement and equity issuances, gross				$ 13,800,000
2017 Private Placement | Common Stock
Subsidiary Sale Of Stock [Line Items]
Private placement, common shares			8,602,589
Proceed from private placement and equity issuances, gross			$ 26,100,000
2017 Direct Registered Offering
Subsidiary Sale Of Stock [Line Items]
Aggregate gross proceeds from issuance of common stock		$ 49,900,000
2017 Direct Registered Offering | Common Stock
Subsidiary Sale Of Stock [Line Items]
Stock issued during period		8,382,643
2018 Direct Registered Offering
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase common stock, shares	1,418,116
Warrant exercise price	$ 8.31
Proceed from private placement and equity issuances, gross	$ 59,100,000
Warrant expiration date	Mar. 31, 2025
2018 Direct Registered Offering | Common Stock
Subsidiary Sale Of Stock [Line Items]
Stock issued during period	4,090,000
2018 Direct Registered Offering | Series A Convertible Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Stock issued during period	3,000,581

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2018	Apr. 19, 2018	Dec. 31, 2017
Convertible Preferred Stock [Line Items]
Preferred stock conversion rate		100.00%
Convertible preferred stock, shares outstanding	0		0
Series A Convertible Preferred Stock | 2018 Direct Registered Offering
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares issued	3,000,581
Stock price	$ 8.31
Convertible preferred stock, beneficial conversion feature	$ 2.7

Warrants - Additional Informati

Warrants - Additional Information (Detail) $ / shares in Units, $ in Thousands

Aug. 22, 2016USD ($)

Jan. 31, 2017USD ($)$ / sharesshares

Sep. 30, 2016USD ($)$ / sharesshares

Aug. 31, 2016$ / sharesshares

Aug. 31, 2015$ / sharesshares

Jul. 31, 2015$ / sharesshares

Jun. 30, 2018USD ($)shares

Mar. 31, 2018USD ($)Year$ / sharesshares

Jun. 30, 2017USD ($)

Jun. 30, 2018USD ($)shares

Jun. 30, 2017USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2013$ / sharesshares

Common Stock Warrants [Line Items]

(Gain) loss related to change in fair value

$ (7,009)

$ 9,032

Fair value of warrants

$ 15,411

15,411

$ 22,420

Fair Value Measurement on Recurring Basis

Common Stock Warrants [Line Items]

Fair value of warrants

$ 15,411

$ 15,411

22,420

2016 Private Placement

Common Stock Warrants [Line Items]

Proceed from private placement and equity issuances, gross

$ 13,800

Fair value of warrants upon issuance

$ 2,700

Common Stock Warrants

Common Stock Warrants [Line Items]

Warrants issued | shares

128,231

Exercise price | $ / shares

$ 5.84

Common stock warrants, expiration date

Dec. 16, 2023

2015 Placement Common Stock Warrants | Insiders

Common Stock Warrants [Line Items]

Warrants issued | shares

198,760

198,760

Exercise price | $ / shares

$ 5

$ 5

Common stock warrants, expiry term

5 years

5 years

Class of warrant exercised | shares

5,498

5,498

Stock issued during period | shares

1,773

1,773

Placement warrants outstanding | shares

193,262

193,262

2018 Offering Warrants

Common Stock Warrants [Line Items]

Warrants issued | shares

1,418,116

Exercise price | $ / shares

$ 8.31

Common stock warrants, expiration date

Mar. 31, 2025

2018 Offering Warrants | 2018 Direct Registered Offering

Common Stock Warrants [Line Items]

Proceed from private placement and equity issuances, gross

$ 59,100

Fair value of warrants upon issuance

7,400

Proceeds from offering warrants

$ 6,600

2018 Offering Warrants | 2018 Direct Registered Offering | Expected Term

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs | Year

7

2018 Offering Warrants | 2018 Direct Registered Offering | Expected Volatility

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

62.50%

2018 Offering Warrants | 2018 Direct Registered Offering | Risk-free Interest Rate

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

2.80%

2018 Offering Warrants | 2018 Direct Registered Offering | Expected Dividend Yield

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

0.00%

2016 Placement Warrants

Common Stock Warrants [Line Items]

Warrants issued | shares

1,380,745

1,380,745

Exercise price | $ / shares

$ 2.95

$ 2.95

Common stock warrants, expiry term

7 years

7 years

Placement warrants outstanding | shares

1,355,641

1,355,641

(Gain) loss related to change in fair value

$ 500

$ (2,800)

$ (3,100)

4,000

2016 Placement Warrants | Fair Value Measurement on Recurring Basis

Common Stock Warrants [Line Items]

Fair value of warrants

$ 6,829

$ 6,829

$ 9,933

2016 Placement Warrants | Expected Term

Common Stock Warrants [Line Items]

Expected term

7 years

5 years 2 months 12 days

5 years 8 months 12 days

2016 Placement Warrants | Expected Volatility

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

61.60%

59.80%

62.10%

2016 Placement Warrants | Risk-free Interest Rate

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

1.40%

2.70%

2.20%

2016 Placement Warrants | Expected Dividend Yield

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

0.00%

0.00%

0.00%

2017 Placement Warrants

Common Stock Warrants [Line Items]

Warrants issued | shares

1,720,512

Exercise price | $ / shares

$ 3.17

Placement warrants outstanding | shares

1,711,123

1,711,123

Proceed from private placement and equity issuances, gross

$ 26,100

Fair value of warrants upon issuance

$ 3,400

(Gain) loss related to change in fair value

$ 700

$ (3,400)

$ (3,900)

$ 5,000

Warrant exercisable date

Jul. 31, 2017

Common stock warrants, expiry date

Jan. 31, 2024

2017 Placement Warrants | Fair Value Measurement on Recurring Basis

Common Stock Warrants [Line Items]

Fair value of warrants

$ 8,582

$ 8,582

$ 12,487

2017 Placement Warrants | Expected Term

Common Stock Warrants [Line Items]

Expected term

7 years

5 years 7 months 6 days

6 years 1 month 6 days

2017 Placement Warrants | Expected Volatility

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

62.90%

60.00%

62.30%

2017 Placement Warrants | Risk-free Interest Rate

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

2.20%

2.80%

2.30%

2017 Placement Warrants | Expected Dividend Yield

Common Stock Warrants [Line Items]

Warrants, fair value measurement inputs

0.00%

0.00%

0.00%

Warrants - Summary of Assumptio

Warrants - Summary of Assumptions to Use Option Pricing Model (Detail)	Aug. 22, 2016	Jan. 31, 2017	Jun. 30, 2018	Dec. 31, 2017
2016 Placement Warrants | Expected Term
Fair Value Inputs1 Liabilities Quantitative Information [Line Items]
Expected term (in years)	7 years		5 years 2 months 12 days	5 years 8 months 12 days
2016 Placement Warrants | Expected Volatility
Fair Value Inputs1 Liabilities Quantitative Information [Line Items]
Warrants, fair value measurement inputs	61.60%		59.80%	62.10%
2016 Placement Warrants | Risk-free Interest Rate
Fair Value Inputs1 Liabilities Quantitative Information [Line Items]
Warrants, fair value measurement inputs	1.40%		2.70%	2.20%
2016 Placement Warrants | Expected Dividend Yield
Fair Value Inputs1 Liabilities Quantitative Information [Line Items]
Warrants, fair value measurement inputs	0.00%		0.00%	0.00%
2017 Placement Warrants | Expected Term
Fair Value Inputs1 Liabilities Quantitative Information [Line Items]
Expected term (in years)		7 years	5 years 7 months 6 days	6 years 1 month 6 days
2017 Placement Warrants | Expected Volatility
Fair Value Inputs1 Liabilities Quantitative Information [Line Items]
Warrants, fair value measurement inputs		62.90%	60.00%	62.30%
2017 Placement Warrants | Risk-free Interest Rate
Fair Value Inputs1 Liabilities Quantitative Information [Line Items]
Warrants, fair value measurement inputs		2.20%	2.80%	2.30%
2017 Placement Warrants | Expected Dividend Yield
Fair Value Inputs1 Liabilities Quantitative Information [Line Items]
Warrants, fair value measurement inputs		0.00%	0.00%	0.00%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Company's Stock Option Activity and Related Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Shares Available for Grant
Shares Available for Grant, Beginning balance	969,783
Shares Available for Grant, Additional options authorized	2,706,158
Shares Available for Grant, Options granted	(2,003,229)
Shares Available for Grant, Options canceled	155,459
Shares Available for Grant, Ending balance	1,828,171	969,783
Number of Stock Options Outstanding
Number of Stock Options Outstanding, Beginning balance	8,592,747
Number of Stock Options Outstanding, Options granted	2,003,229
Number of Stock Options Outstanding, Options exercised	(396,939)
Number of Stock Options Outstanding, Options canceled	(155,459)
Number of Stock Options Outstanding, Ending balance	10,043,578	8,592,747
Number of Stock Options Outstanding, Vested and exercisable	5,411,367
Number of Stock Options Outstanding, Vested and expected to vest	9,701,142
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Beginning balance	$ 3.69
Weighted- Average Exercise Price, Options granted	7.15
Weighted- Average Exercise Price, Options exercised	1.80
Weighted- Average Exercise Price, Options canceled	5.41
Weighted- Average Exercise Price, Ending balance	4.43	$ 3.69
Weighted- Average Exercise Price, Vested and exercisable	3.08
Weighted- Average Exercise Price, Vested and expected to vest	$ 4.38
Weighted- Average Remaining Contractual Life (Years)
Options Outstanding, Weighted- Average Remaining Contractual Life (Years)	7 years 7 months 6 days	7 years 4 months 24 days
Weighted- Average Remaining Contractual Life (Years), Vested and exercisable	6 years 4 months 24 days
Weighted- Average Remaining Contractual Life (Years), Vested and expected to vest	7 years 7 months 6 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 25,933	$ 47,864
Aggregate Intrinsic Value, Vested and exercisable	21,106
Aggregate Intrinsic Value, Vested and expected to vest	$ 25,536

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended			3 Months Ended		6 Months Ended
	Dec. 31, 2017	Nov. 30, 2017	Sep. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant date fair value of options granted, per share						$ 4.18	$ 3.13
Grant date fair value of options vested						$ 2,500,000	$ 1,900,000
Aggregate intrinsic value of option exercised						2,200,000	1,500,000
Unrecognized compensation cost				$ 14,800,000		$ 14,800,000
Weighted average period for recognition of compensation costs						3 years
Stock based compensation expenses				1,683,000	$ 1,013,000	$ 2,873,000	$ 1,782,000
Stock-based compensation expense capitalized				$ 0		$ 0
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Granted						0	0
Stock based compensation expenses						$ 0	$ 0
Restricted Stock Units (RSUs) | Board of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Granted		43,554	112,578
Grant date fair value of RSUs, per share	$ 3.58	$ 8.02	$ 3.58
RSUs Released	18,964
Restricted Stock Units (RSUs) | Executive Officers
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Granted		12,468
Grant date fair value of RSUs, per share		$ 8.02
Restricted Stock Units (RSUs) | Board of Directors (Departure 1)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs expected to released				34,502		34,502
RSUs expected to vest, fair value per share				$ 3.58		$ 3.58
Restricted Stock Units (RSUs) | Board of Directors (Departure 2)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs expected to released				12,467		12,467
RSUs expected to vest, fair value per share				$ 8.02		$ 8.02

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Weighted-Average Assumptions Used in Black-Scholes Option-Pricing Model to Estimate Fair Value of Employee Stock Option at Grant Date (Detail)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (in years)	6 years	6 years
Expected volatility%	61.20%	67.10%
Risk-free interest rate%	2.80%	2.10%
Expected dividend yield%	0.00%	0.00%

Stock-Based Compensation - Su50

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,683	$ 1,013	$ 2,873	$ 1,782
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	347	216	550	381
Selling and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	194	72	321	123
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,142	$ 725	$ 2,002	$ 1,278

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 0	$ 0	$ 0	$ 0
Federal statutory tax rate			21.00%		35.00%
Federal and state effective tax rate			22.00%
Unrecognized tax benefits	$ 1,300,000		$ 1,300,000		$ 1,100,000
Accrued interest and penalties related to uncertain tax positions			$ 0		$ 0

Net Loss Per Share - Anti-Dilut

Net Loss Per Share - Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	15,253,867	11,545,065	14,354,707	10,940,071
Series A Convertible Preferred Stock (If Converted)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	593,522	0	746,001	0
Options To Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	9,714,129	8,006,323	9,157,418	7,561,888
Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	4,811,629	3,428,248	4,315,410	3,266,653
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	134,587	110,494	135,878	111,530

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($)	1 Months Ended
	Jan. 31, 2017	Dec. 31, 2014	Dec. 31, 2004
University Of Florida Research Foundation | Licensing Agreements
Related Party Transaction [Line Items]
Common Stock granted in exchange for licensing		33,652
Percentage of royalty payment based on sale			1.00%
Royalty payment per quarter		$ 50,000
Investment Manager of Investment Company | Sales Consulting Agreement [Member]
Related Party Transaction [Line Items]
Related party, agreement term	1 year
Related party, total consideration	$ 1,300,000