Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Contract revenues	$ 385,818us-gaap_ContractsRevenue	$ 354,544us-gaap_ContractsRevenue	$ 292,042us-gaap_ContractsRevenue
Costs of contract revenues	341,224us-gaap_ContractRevenueCost	322,540us-gaap_ContractRevenueCost	277,672us-gaap_ContractRevenueCost
Gross profit	44,594us-gaap_GrossProfit	32,004us-gaap_GrossProfit	14,370us-gaap_GrossProfit
Selling, general and administrative expenses	34,691	32,110	28,573
Operating income (loss)	9,903us-gaap_OperatingIncomeLoss	(106)us-gaap_OperatingIncomeLoss	(14,203)us-gaap_OperatingIncomeLoss
Other income (expense):
Gain (loss) from sale of assets, net	359	(153)	(1,822)
Other income	467us-gaap_NonoperatingIncomeExpense	165us-gaap_NonoperatingIncomeExpense	227us-gaap_NonoperatingIncomeExpense
Interest income	17	13	35
Interest expense	(694)us-gaap_InterestExpense	(525)us-gaap_InterestExpense	(743)us-gaap_InterestExpense
Other income (expense), net	149us-gaap_OtherNonoperatingIncomeExpense	(500)us-gaap_OtherNonoperatingIncomeExpense	(2,303)us-gaap_OtherNonoperatingIncomeExpense
Income (loss) before income taxes	10,052	(606)	(16,506)
Income tax expense (benefit)	3,175us-gaap_IncomeTaxExpenseBenefit	(937)us-gaap_IncomeTaxExpenseBenefit	(4,640)us-gaap_IncomeTaxExpenseBenefit
Net income (loss)	6,877us-gaap_NetIncomeLoss	331us-gaap_NetIncomeLoss	(11,866)us-gaap_NetIncomeLoss
Net income (loss) attributable to noncontrolling interest	$ 0	$ 0	$ 0
Basic loss per share (in dollars per share)	$ 0.25us-gaap_EarningsPerShareBasic	$ 0.01us-gaap_EarningsPerShareBasic	$ (0.44)us-gaap_EarningsPerShareBasic
Diluted loss per share (in dollars per share)	$ 0.25us-gaap_EarningsPerShareDiluted	$ 0.01us-gaap_EarningsPerShareDiluted	$ (0.44)us-gaap_EarningsPerShareDiluted
Shares used to compute income (loss) per share
Basic (shares)	27,421,441	27,296,732	27,138,927
Diluted (shares)	27,787,613	27,613,054	27,138,927

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