Receivables, Net (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	$ 328,278,000				$ 254,718,000				$ 328,278,000	$ 254,718,000
Allowance for Accounts, Notes, Loans and Financing Receivable, Current	2,749,000				2,880,000				2,749,000	2,880,000
Receivables, net	325,529,000				251,838,000				325,529,000	251,838,000
Accounts Notes Loans and Financing Receivable Gross Current, Due In One Year From Balance Sheet	71,000,000								71,000,000
Accounts Notes Loans and Financing Receivable Gross Current, Due In Two Years From Balance Sheet	15,500,000								15,500,000
Accounts Notes Loans and Financing Receivable Gross Current, Due In Three Years From Balance Sheet	7,300,000								7,300,000
Segment Reporting Information, Revenue for Reportable Segment									2,262,428,000	2,204,566,000	1,960,262,000
Revenue, Net	504,781,000	728,482,000	539,615,000	310,160,000	539,548,000	728,578,000	484,674,000	256,731,000	2,083,037,000	2,009,531,000	1,762,965,000
Notes Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes, Loans and Financing Receivable, Net, Noncurrent	2,000,000								2,000,000
Construction Contracts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	289,044,000				200,025,000				289,044,000	200,025,000
Completed and in Progress [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	195,244,000				122,987,000				195,244,000	122,987,000
Retentions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	93,800,000				77,038,000				93,800,000	77,038,000
Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	41,494,000				43,378,000				41,494,000	43,378,000
Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	52,306,000				33,660,000				52,306,000	33,660,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	44,317,000				27,125,000				44,317,000	27,125,000
Non-escrow retention receivable - 0 to 90 days past due	2,372,000				3,277,000				2,372,000	3,277,000
Non-escrow retention receivable - over 90 days past due	5,617,000				3,258,000				5,617,000	3,258,000
Construction Material Sales [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	26,918,000				30,356,000				26,918,000	30,356,000
Other Business Products and Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	12,316,000				24,337,000				12,316,000	24,337,000
Government [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage Of Revenue Attributable to Counterparty by Industry									80.60%	83.80%	83.30%
Government [Member] | Construction And Large Project Contruction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Segment Reporting Information, Revenue for Reportable Segment									1,700,000,000	1,700,000,000	1,500,000,000
Federal [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	3,234,000				2,811,000				3,234,000	2,811,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	3,116,000				2,462,000				3,116,000	2,462,000
Non-escrow retention receivable - 0 to 90 days past due	72,000				326,000				72,000	326,000
Non-escrow retention receivable - over 90 days past due	46,000				23,000				46,000	23,000
State [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	2,971,000				5,453,000				2,971,000	5,453,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	2,148,000				2,751,000				2,148,000	2,751,000
Non-escrow retention receivable - 0 to 90 days past due	502,000				860,000				502,000	860,000
Non-escrow retention receivable - over 90 days past due	321,000				1,842,000				321,000	1,842,000
California Department of Transportation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenue, Net									272,900,000	264,900,000	175,000,000
Percentage Of Revenue Attributable to Counterparty by Industry									13.10%	13.20%	9.90%
Maryland State Highway Administration [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenue, Net											181,000,000
Percentage Of Revenue Attributable to Counterparty by Industry											10.30%
Local [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	31,559,000				14,708,000				31,559,000	14,708,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	25,743,000				12,313,000				25,743,000	12,313,000
Non-escrow retention receivable - 0 to 90 days past due	1,082,000				1,326,000				1,082,000	1,326,000
Non-escrow retention receivable - over 90 days past due	4,734,000				1,069,000				4,734,000	1,069,000
Private [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	14,542,000				10,688,000				14,542,000	10,688,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	13,310,000				9,599,000				13,310,000	9,599,000
Non-escrow retention receivable - 0 to 90 days past due	716,000				765,000				716,000	765,000
Non-escrow retention receivable - over 90 days past due	$ 516,000				$ 324,000				$ 516,000	$ 324,000