FAIR VALUE MEASUREMENTS (Details) $ / shares in Units, item in Thousands, $ in Millions	1 Months Ended	9 Months Ended	12 Months Ended
Mar. 31, 2010 USD ($) item $ / shares	Sep. 30, 2020 USD ($) payment item	Dec. 31, 2019 USD ($)
Fair Value Measurement [Line Items]
Cumulative liability		$ 20.0	$ 19.3
Manhattan and Ariston Pharmaceuticals Merger [Member]
Fair Value Measurement [Line Items]
Notes Issued	$ 15.5
Debt instrument, term	5 years
Det instrument rate	5.00%
Debt Instrument convertible conversion price \| $ / shares	$ 1,125
Percentage of cash proceeds from operation to repay convertible debt	50.00%
Number of obligations \| item	0
Convertible Notes Payable [Member]
Fair Value Measurement [Line Items]
Det instrument rate	5.00%	5.00%	5.00%
Debt Instrument convertible conversion price \| $ / shares	$ 1,125
Percentage of cash proceeds from operation to repay convertible debt	50.00%
Number of obligations \| item		0
Cumulative liability		$ 20.0	$ 19.3
Number of payments \| payment		0

This element represents about cumulative liability.

No definition available.

Name:	tgtx_CumulativeLiabilityOfNote
Namespace Prefix:	tgtx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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Namespace Prefix:	tgtx_
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Period Type:	duration

- Definition

Refers to the number of obligations.

+ References

No definition available.

+ Details

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Namespace Prefix:	tgtx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of payment made.

+ References

No definition available.

+ Details

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Namespace Prefix:	tgtx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Reflects level of percentage of net product cash flow received from the exploitation or commercialization of certain product candidates to repay certain convertible debt.

+ References

No definition available.

+ Details

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Namespace Prefix:	tgtx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
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- Definition

The average effective interest rate during the reporting period.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
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Period Type:	duration

- Definition

The fair value of notes issued in noncash investing and financing activities.

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	duration

- Details

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- Details

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