Number of persons employed by the Entity

No definition available.

Name:	dei_EntityNumberOfEmployees
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- Definition

Represents the additional amount of potential payments that could result from the contingent consideration arrangement.

+ References

No definition available.

+ Details

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- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents evaluation period for determining amount of payment.

+ References

No definition available.

+ Details

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- Definition

Represents the amount of EBITDA (income before interest, taxes, depreciation and amortization) to be achieved by the acquiree in earnout target period to measure payment of potential contingent consideration.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Represents the number of installments in which the earn out is payable to the selling shareholders.

+ References

No definition available.

+ Details

Name:	hil_NumberOfAnnualInstallments
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Data Type:	xbrli:integerItemType
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Period Type:	duration

- Definition

Represents the number of selling shareholders to whom earn out is payable.

+ References

No definition available.

+ Details

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- Details

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 7

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-Section 50

-Paragraph 1

-Subparagraph (b)

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- Definition

Amount of liabilities incurred by the acquirer as part of consideration transferred in a business combination.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 25

-Paragraph 5

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- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)(3)

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- Definition

For contingent consideration arrangements and indemnification assets recognized in connection with a business combination, this element represents an estimate of the low-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

+ Details

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- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (b)

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Acquisitions (Details) (Cadogans)	3 Months Ended		0 Months Ended								3 Months Ended			3 Months Ended
Acquisitions (Details) (Cadogans)	Mar. 31, 2015 USD ($)	Mar. 31, 2015 GBP (£)	Oct. 31, 2015 Hill International (UK) Ltd USD ($)	Oct. 31, 2015 Hill International (UK) Ltd GBP (£)	Dec. 23, 2014 Hill International (UK) Ltd USD ($)	Dec. 23, 2014 Hill International (UK) Ltd GBP (£)	Nov. 25, 2014 Hill International (UK) Ltd USD ($)	Nov. 25, 2014 Hill International (UK) Ltd GBP (£)	Oct. 31, 2014 Hill International (UK) Ltd USD ($) item	Oct. 31, 2014 Hill International (UK) Ltd GBP (£)	Mar. 31, 2015 Hill International (UK) Ltd USD ($)	Mar. 31, 2015 Hill International (UK) Ltd GBP (£)	Oct. 31, 2014 Hill International (UK) Ltd GBP (£) item	Mar. 31, 2015 Hill International (UK) Ltd Other Current Liabilities USD ($)	Mar. 31, 2015 Hill International (UK) Ltd Other Current Liabilities GBP (£)	Mar. 31, 2015 Hill International (UK) Ltd Other Liabilities USD ($)	Mar. 31, 2015 Hill International (UK) Ltd Other Liabilities GBP (£)
Acquisitions
Number of professionals													27
Total consideration for acquisition									$ 4,350,000	£ 2,719,000
Cash payment			830,000	519,000	640,000	400,000	960,000	600,000	1,600,000	1,000,000
Contingent consideration arrangement, evaluation period	2 years	2 years							2 years	2 years
Contingent consideration, minimum		0											0
Contingent consideration		200,000											200,000
Number Of Selling Shareholders									2	2
Number Of Annual Installments									5	5
Maximum annual earn out installment									160,000	100,000
EBITDA threshold for the five succeeding years for measuring financial performance									633,000	396,000
Acquisition consideration payable	$ 830,000	£ 519,000									$ 1,150,000	£ 719,000		$ 830,000	£ 519,000	$ 320,000	£ 200,000