CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$ 1,672us-gaap_ProfitLoss	$ 11,265us-gaap_ProfitLoss
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	13,854us-gaap_Depreciation	11,709us-gaap_Depreciation
Amortization of intangible assets	1,651us-gaap_AmortizationOfIntangibleAssets	1,843us-gaap_AmortizationOfIntangibleAssets
Loss (gain) on sale of property and equipment	510	(355)
Income from non-consolidated entities		(14)
Stock-based compensation expense	262us-gaap_ShareBasedCompensation	137us-gaap_ShareBasedCompensation
Changes in assets and liabilities:
Customer retention deposits and restricted cash	(342)	5,249
Accounts receivable	41,236us-gaap_IncreaseDecreaseInReceivables	15,831us-gaap_IncreaseDecreaseInReceivables
Costs and estimated earnings in excess of billings	(16,164)	(17,921)
Other current assets	(7,065)	(7,938)
Accounts payable	(8,487)	(8,213)
Billings in excess of costs and estimated earnings	(13,453)	(26,064)
Contingent earnout liabilities	(4,955)	(4,886)
Accrued expenses and other current liabilities	(6,421)	1,534
Other long-term liabilities	(280)	(3,855)
Net cash provided by (used in) operating activities	2,018	(21,678)
Cash flows from investing activities:
Purchase of property and equipment	(16,581)	(15,067)
Proceeds from sale of property and equipment	2,823	1,391
Purchase of short-term investments		(586)
Sale of short-term investments	498	1,946
Cash received for the sale of Alvah minority interest		1,189
Cash paid for acquisitions	(22,302)prim_PaymentsForAcquisitions
Net cash used in investing activities	(35,562)	(11,127)
Cash flows from financing activities:
Proceeds from issuance of long-term debt	11,000
Repayment of capital leases	(367)	(1,079)
Repayment of long-term debt	(10,095)us-gaap_RepaymentsOfLongTermDebt	(11,314)us-gaap_RepaymentsOfLongTermDebt
Proceeds from issuance of common stock purchased under a long-term incentive plan	1,621	1,671
Dividends paid	(2,062)us-gaap_PaymentsOfDividendsCommonStock	(1,805)us-gaap_PaymentsOfDividendsCommonStock
Cash distribution to non-controlling interest holder		(1,125)us-gaap_PaymentsToMinorityShareholders
Net cash provided by (used in) financing activities	97	(13,652)
Net change in cash and cash equivalents	(33,447)	(46,457)
Cash and cash equivalents at beginning of the period	139,465	196,077
Cash and cash equivalents at end of the period	106,018	149,620
Cash paid during the period for:
Interest	1,922us-gaap_InterestPaid	1,508us-gaap_InterestPaid
Income taxes, net of refunds received	505us-gaap_IncomeTaxesPaid	2,341us-gaap_IncomeTaxesPaid
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES
Dividends declared and not yet paid	$ 2,063	$ 1,808

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee and excludes impairment expense.