Estimated Fair Value of Financial Instruments - Warrant Liability (Details) - USD ($)		3 Months Ended	12 Months Ended
Jun. 30, 2017	Sep. 30, 2017	Jun. 30, 2017
Changes in the estimated fair value for warrant liability
Reclass of warrant liability to capital contributed in excess of par due to exercise		$ (11,241,662)
Change in fair value	$ 2,600,000	86,378,330
Warrant Liability.
Changes in the estimated fair value for warrant liability
Fair value at beginning of year		18,655,804
Reclass of warrant liability to capital contributed in excess of par due to exercise		(1,575,000)
Fair value at end of year	18,655,804	17,080,804	$ 18,655,804
Warrant Liability. \| Level 2
Changes in the estimated fair value for warrant liability
Fair value at beginning of year		90,706,000
Reclass of warrant liability to capital contributed in excess of par due to exercise		(11,241,000)
Change in fair value		86,378,000
Fair value at end of year	$ 90,706,000	$ 165,843,000	$ 90,706,000
Warrant Liability. \| February 10, 2017 stock purchase agreement
Fair value assumptions for warrants
Risk-free interest rate		1.06%	1.14%
Expected remaining term		3 months 4 days	6 months 4 days
Expected volatility		63.73%	69.34%
Dividend yield		0.00%	0.00%
Warrant Liability. \| October 11, 2016 public offering
Fair value assumptions for warrants
Risk-free interest rate		1.31%	1.38%
Expected remaining term		1 year 11 days	1 year 3 months 11 days
Expected volatility		70.69%	73.85%
Dividend yield		0.00%	0.00%

Reclass of warrant liability to capital contributed in excess of par.

No definition available.

Name:	immu_ReclassOfWarrantLiabilityToCapitalContributedInExcessOfPar
Namespace Prefix:	immu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of expense (income) related to adjustment to fair value of warrant liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section 25
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=6939902&loc=d3e20148-110875

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

+ Details

Name:	us-gaap_FairValueAdjustmentOfWarrants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

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).

+ References

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

- References

No definition available.

+ Details

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

- Definition

Fair value portion of warrants not settleable in cash classified as equity.

+ References

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

+ Details

Name:	us-gaap_WarrantsNotSettleableInCashFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=us-gaap_WarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=immu_WarrantsIssuedIn10February2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=immu_WarrantsIssuedInOctober2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: