Warrants - Summary of Assumptions to Use Option Pricing Model (Detail)		1 Months Ended	9 Months Ended	12 Months Ended
Aug. 22, 2016	Jan. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
2016 Placement Warrant
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Expected term (in years)	7 years		5 years 10 months 25 days	6 years 8 months 12 days
Expected volatility	61.60%		63.00%	63.60%
Risk-free interest rate	1.40%		2.00%	2.30%
Expected dividend yield	0.00%		0.00%	0.00%
2017 Placement Warrant
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Expected term (in years)		7 years	6 years 3 months 19 days
Expected volatility		62.90%	63.80%
Risk-free interest rate		2.20%	2.10%
Expected dividend yield		0.00%	0.00%

Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueAssumptionsExpectedDividendRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_FairValueAssumptionsExpectedTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

+ References

+ Details

Name:	us-gaap_FairValueAssumptionsExpectedVolatilityRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Risk-free interest rate assumption used in valuing an instrument.

+ References

+ Details

Name:	us-gaap_FairValueAssumptionsRiskFreeInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=vray_TwoThousandAndSixteenPrivatePlacementWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=vray_TwoThousandAndSeventeenPrivatePlacementWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: