Business Overview (Details)	9 Months Ended
Jun. 30, 2015 employee business_area location	Jun. 30, 2014
Concentration Risk [Line Items]
Minimum period for which entity has provided professional services to the U.S. Government (years)	25 years
Number of employees (employee) \| employee	1,200
Minimum number of locations in which entity operates (location) \| location	25
Number of broad integrated revenue streams	2
US Government [Member] \| Revenue concentration \| Customer concentration
Concentration Risk [Line Items]
Concentration risk percentage (percent)	100.00%	100.00%
DVA \| Revenue concentration \| Customer concentration
Concentration Risk [Line Items]
Concentration risk percentage (percent)	95.00%	97.00%
DVA \| Minimum
Concentration Risk [Line Items]
Term of government contract	1 year
DVA \| Maximum
Concentration Risk [Line Items]
Term of government contract	3 years

Number of persons employed by the Entity

No definition available.

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Namespace Prefix:	dei_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of integrated revenue streams areas of the entity.

+ References

No definition available.

+ Details

Name:	dlhc_EntityNumberofIntegratedRevenueStreams
Namespace Prefix:	dlhc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period for which the entity has provided professional services to U.S. Government.

+ References

No definition available.

+ Details

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Namespace Prefix:	dlhc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the term of the award granted to the entity.

+ References

No definition available.

+ Details

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Namespace Prefix:	dlhc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the minimum number of locations the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

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

- 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

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 18

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13537-108611

+ Details

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Period Type:	duration

- Details

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- Details

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- Details

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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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- Details

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