Receivables, Net (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	$ 425,174,000	$ 328,278,000	$ 365,880,000
Allowance for Accounts, Notes, Loans and Financing Receivable, Current	2,565,000	2,749,000	2,425,000
Receivables, net	422,609,000	325,529,000	363,455,000
Notes, Loans and Financing Receivable, Net, Noncurrent	1,500,000	2,000,000	1,900,000
Construction Contracts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	351,296,000	289,044,000	297,455,000
Completed and in Progress [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	275,182,000	195,244,000	228,865,000
Retentions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	76,114,000	93,800,000	68,590,000
Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	23,794,000	41,494,000	42,297,000
Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	52,320,000	52,306,000	26,293,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	35,889,000	44,317,000	23,825,000
Non-escrow retention receivable - 1 to 90 days past due	4,497,000	2,372,000	1,115,000
Non-escrow retention receivable - over 90 days past due	11,934,000	5,617,000	1,353,000
Construction Material Sales [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	55,466,000	26,918,000	59,396,000
Other Business Products and Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	18,412,000	12,316,000	9,029,000
Federal [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	5,161,000	3,234,000	2,569,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	4,121,000	3,116,000	2,012,000
Non-escrow retention receivable - 1 to 90 days past due	237,000	72,000	0
Non-escrow retention receivable - over 90 days past due	803,000	46,000	557,000
State [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	3,444,000	2,971,000	3,595,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	1,685,000	2,148,000	3,177,000
Non-escrow retention receivable - 1 to 90 days past due	368,000	502,000	239,000
Non-escrow retention receivable - over 90 days past due	1,391,000	321,000	179,000
Local [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	35,003,000	31,559,000	12,003,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	24,845,000	25,743,000	11,141,000
Non-escrow retention receivable - 1 to 90 days past due	2,924,000	1,082,000	555,000
Non-escrow retention receivable - over 90 days past due	7,234,000	4,734,000	307,000
Private [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	8,712,000	14,542,000	8,126,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	5,238,000	13,310,000	7,495,000
Non-escrow retention receivable - 1 to 90 days past due	968,000	716,000	321,000
Non-escrow retention receivable - over 90 days past due	$ 2,506,000	$ 516,000	$ 310,000