Represents information pertaining to billed but not installed inventory during the reporting period.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the minimum percentage of revenue typically generated by specified number of customers in any one calendar year.

+ References

No definition available.

+ Details

Name:	prim_ConcentrationRiskMinimumPercentageOfRevenuesGeneratedBySpecifiedNumberOfTopCustomers
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of calendar years in which top customers typically generate minimum specified percentage of revenue.

+ References

No definition available.

+ Details

Name:	prim_ConcentrationRiskNumberOfCalendarYearsInWhichTopCustomersGenerateSpecifiedPercentageOfRevenue
Namespace Prefix:	prim_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of customers who typically contribute accounts receivable in excess of a specified percentage.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of top customers who typically generate revenue in excess of a specified percentage of total revenues for the entity and consist of a different group of customers in each year.

+ References

No definition available.

+ Details

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Namespace Prefix:	prim_
Data Type:	xbrli:integerItemType
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- Details

Name:	us-gaap_ConcentrationRiskLineItems
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Balance Type:	na
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 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13537-108611

Reference 2: 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 3: 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=28364263&loc=d3e13531-108611

Reference 4: 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

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(d))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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Basis of Presentation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Customer concentration
Revenues	$ 515,291	$ 445,013	$ 985,365	$ 855,008
Billed but uninstalled inventory	46,972	30,012	46,972	30,012
Revenues \| Customer concentration \| Top ten customers
Customer concentration
Number of top customers	10	10	10	10
Number of calendar years in which top customers typically generate minimum specified percentage of revenue			1
Revenues	$ 293,000	$ 216,000	$ 575,000	$ 443,000
Percentage of concentration risk	56.80%	48.60%	58.40%	51.90%
Revenues \| Customer concentration \| Top ten customers \| Minimum
Customer concentration
Minimum percentage of revenues generated by top ten customers			50.00%
Revenues \| Customer concentration \| Large gas and electric utility
Customer concentration
Percentage of concentration risk		7.60%		8.00%
Revenues \| Customer concentration \| One customer
Customer concentration
Percentage of concentration risk			8.00%	6.40%
Revenues \| Customer concentration \| TX DOT
Customer concentration
Percentage of concentration risk	9.00%		9.20%
Revenues \| Customer concentration \| Large gas pipeline company
Customer concentration
Percentage of concentration risk	8.80%	8.20%	8.20%	5.00%
Accounts receivable \| Customer concentration \| One customer
Customer concentration
Percentage of concentration risk			15.20%	6.50%
Number of customers			1	1