Receivables, Net (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	$ 287,084,000	$ 247,283,000	$ 299,411,000
Allowance for Accounts, Notes, Loans and Financing Receivable, Current	3,140,000	3,297,000	3,632,000
Receivables, net	283,944,000	243,986,000	295,779,000
Notes, Loans and Financing Receivable, Net, Noncurrent	2,100,000	1,800,000	3,000,000
Federal [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	3,421,000	3,080,000	1,471,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	3,025,000	2,587,000	738,000
Non-escrow retention receivable - 0 to 90 days past due	0	174,000	311,000
Non-escrow retention receivable - over 90 days past due	396,000	319,000	422,000
State [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	7,928,000	9,507,000	11,541,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	6,951,000	4,443,000	9,472,000
Non-escrow retention receivable - 0 to 90 days past due	29,000	628,000	544,000
Non-escrow retention receivable - over 90 days past due	948,000	4,436,000	1,525,000
Local [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	20,282,000	29,451,000	25,668,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	16,294,000	22,641,000	20,874,000
Non-escrow retention receivable - 0 to 90 days past due	1,432,000	2,800,000	1,463,000
Non-escrow retention receivable - over 90 days past due	2,556,000	4,010,000	3,331,000
Private [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	9,601,000	10,454,000	10,957,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	9,028,000	9,243,000	9,537,000
Non-escrow retention receivable - 0 to 90 days past due	222,000	175,000	465,000
Non-escrow retention receivable - over 90 days past due	351,000	1,036,000	955,000
Construction Contracts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	235,405,000	217,997,000	244,316,000
Completed and in Progress [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	155,807,000	121,664,000	155,343,000
Retentions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	79,598,000	96,333,000	88,973,000
Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	38,366,000	43,841,000	39,336,000
Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	41,232,000	52,492,000	49,637,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	35,298,000	38,914,000	40,621,000
Non-escrow retention receivable - 0 to 90 days past due	1,683,000	3,777,000	2,783,000
Non-escrow retention receivable - over 90 days past due	4,251,000	9,801,000	6,233,000
Construction Material Sales [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	39,074,000	17,674,000	39,989,000
Other Business Products and Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	$ 12,605,000	$ 11,612,000	$ 15,106,000