Investments - Variable Interest Entity (Details) - Variable Interest Entity - USD ($) $ in Millions	1 Months Ended	3 Months Ended
Apr. 30, 2017	Sep. 30, 2017
Variable Interest Entity
Funding period for additional research and development	6 years
Amount of financial support provided	$ 5.2
Carrying amount of cash		$ 9.6
Carrying amount of in-process research and development intangible assets		8.8
carrying amount of goodwill		3.4
Carrying amount of preferred stock		8.3
Net loss of consolidation entity		$ 1.5
Privately-held Companies
Variable Interest Entity
Investment purchased during the period	$ 7.5

Description of the amount of pre-tax income (loss) derived by the reporting entity from the Variable Interest Entity (VIE).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph d
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5747-111685

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of financial or other support the reporting entity has provided (explicitly or implicitly) to the Variable Interest Entity (VIE) that it was not previously contractually required to provide or that the reporting entity intends to provide, including, for example, situations in which the reporting entity assisted the VIE in obtaining another type of support.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=SL6759159-111685

+ Details

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

- Definition

The duration of control rights relate to additional research and development funding that we may provide to the other company

+ References

No definition available.

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Balance Type:	na
Period Type:	duration

- Definition

Cost method investments purchased during the period.

+ References

No definition available.

+ Details

Name:	uthr_CostMethodInvestmentsPurchased
Namespace Prefix:	uthr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying amount of the consolidated Variable Interest Entity's cash included in the reporting entity's statement of financial position.

+ References

No definition available.

+ Details

Name:	uthr_VariableInterestEntityConsolidatedCarryingAmountCash
Namespace Prefix:	uthr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's goodwill included in the reporting entity's statement of financial position.

+ References

No definition available.

+ Details

Name:	uthr_VariableInterestEntityConsolidatedCarryingAmountGoodwill
Namespace Prefix:	uthr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's of in-process research and development intangible assets included in the reporting entity's statement of financial position.

+ References

No definition available.

+ Details

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Namespace Prefix:	uthr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's preferred stock included in the reporting entity's statement of financial position.

+ References

No definition available.

+ Details

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Namespace Prefix:	uthr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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- Details

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