Receivables, Net (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	$ 365,880,000	$ 254,718,000	$ 360,421,000
Allowance for Accounts, Notes, Loans and Financing Receivable, Current	2,425,000	2,880,000	2,614,000
Receivables, net	363,455,000	251,838,000	357,807,000
Notes, Loans and Financing Receivable, Net, Noncurrent	1,900,000	2,000,000	2,100,000
Construction Contracts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	297,455,000	200,025,000	298,087,000
Completed and in Progress [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	228,865,000	122,987,000	223,292,000
Retentions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	68,590,000	77,038,000	74,795,000
Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	42,297,000	43,378,000	38,517,000
Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	26,293,000	33,660,000	36,278,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	23,825,000	27,125,000	29,568,000
Non-escrow retention receivable - 0 to 90 days past due	1,115,000	3,277,000	3,047,000
Non-escrow retention receivable - over 90 days past due	1,353,000	3,258,000	3,663,000
Construction Material Sales [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	59,396,000	30,356,000	52,157,000
Other Business Products and Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	9,029,000	24,337,000	10,177,000
Federal [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	2,569,000	2,811,000	2,148,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	2,012,000	2,462,000	1,976,000
Non-escrow retention receivable - 0 to 90 days past due	0	326,000	77,000
Non-escrow retention receivable - over 90 days past due	557,000	23,000	95,000
State [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	3,595,000	5,453,000	6,046,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	3,177,000	2,751,000	3,880,000
Non-escrow retention receivable - 0 to 90 days past due	239,000	860,000	1,397,000
Non-escrow retention receivable - over 90 days past due	179,000	1,842,000	769,000
Local [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	12,003,000	14,708,000	17,666,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	11,141,000	12,313,000	13,801,000
Non-escrow retention receivable - 0 to 90 days past due	555,000	1,326,000	1,465,000
Non-escrow retention receivable - over 90 days past due	307,000	1,069,000	2,400,000
Private [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	8,126,000	10,688,000	10,418,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	7,495,000	9,599,000	9,911,000
Non-escrow retention receivable - 0 to 90 days past due	321,000	765,000	108,000
Non-escrow retention receivable - over 90 days past due	$ 310,000	$ 324,000	$ 399,000