Receivables, Net (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	$ 339,011,000	$ 328,278,000	$ 275,603,000
Allowance for Accounts, Notes, Loans and Financing Receivable, Current	2,593,000	2,749,000	3,041,000
Receivables, net	336,418,000	325,529,000	272,562,000
Notes, Loans and Financing Receivable, Net, Noncurrent	1,600,000	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	283,776,000	289,044,000	212,774,000
Completed and in Progress [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	207,488,000	195,244,000	146,509,000
Retentions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	76,288,000	93,800,000	66,265,000
Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	31,892,000	41,494,000	42,421,000
Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	44,396,000	52,306,000	23,844,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	33,811,000	44,317,000	18,991,000
Non-escrow retention receivable - 1 to 90 days past due	2,985,000	2,372,000	1,626,000
Non-escrow retention receivable - over 90 days past due	7,600,000	5,617,000	3,227,000
Construction Material Sales [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	43,535,000	26,918,000	50,205,000
Other Business Products and Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	11,700,000	12,316,000	12,624,000
Federal [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	3,325,000	3,234,000	2,464,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	2,551,000	3,116,000	1,746,000
Non-escrow retention receivable - 1 to 90 days past due	236,000	72,000	0
Non-escrow retention receivable - over 90 days past due	538,000	46,000	718,000
State [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	2,757,000	2,971,000	4,626,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	1,327,000	2,148,000	3,552,000
Non-escrow retention receivable - 1 to 90 days past due	619,000	502,000	208,000
Non-escrow retention receivable - over 90 days past due	811,000	321,000	866,000
Local [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	32,500,000	31,559,000	9,944,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	25,362,000	25,743,000	7,330,000
Non-escrow retention receivable - 1 to 90 days past due	1,496,000	1,082,000	1,326,000
Non-escrow retention receivable - over 90 days past due	5,642,000	4,734,000	1,288,000
Private [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	5,814,000	14,542,000	6,810,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	4,571,000	13,310,000	6,363,000
Non-escrow retention receivable - 1 to 90 days past due	634,000	716,000	92,000
Non-escrow retention receivable - over 90 days past due	$ 609,000	$ 516,000	$ 355,000