Receivables, Net (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	$ 364,157,000	$ 316,111,000	$ 339,011,000
Allowance for Accounts, Notes, Loans and Financing Receivable, Current	543,000	2,513,000	2,593,000
Receivables, net	363,614,000	313,598,000	336,418,000
Notes, Loans and Financing Receivable, Net, Noncurrent	1,100,000	1,300,000	1,600,000
Construction Contracts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	307,548,000	266,641,000	283,776,000
Completed and in Progress [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	237,870,000	193,538,000	207,488,000
Retentions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	69,678,000	73,103,000	76,288,000
Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	25,093,000	25,124,000	31,892,000
Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	44,585,000	47,979,000	44,396,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	38,170,000	39,284,000	33,811,000
Non-escrow retention receivable - 1 to 90 days past due	929,000	1,650,000	2,985,000
Non-escrow retention receivable - over 90 days past due	5,486,000	7,045,000	7,600,000
Construction Material Sales [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	48,932,000	36,813,000	43,535,000
Other Business Products and Services [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	7,677,000	12,657,000	11,700,000
Federal [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	1,543,000	2,878,000	3,325,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	1,532,000	2,843,000	2,551,000
Non-escrow retention receivable - 1 to 90 days past due	0	13,000	236,000
Non-escrow retention receivable - over 90 days past due	11,000	22,000	538,000
State [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	5,078,000	5,579,000	2,757,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	4,837,000	4,919,000	1,327,000
Non-escrow retention receivable - 1 to 90 days past due	168,000	326,000	619,000
Non-escrow retention receivable - over 90 days past due	73,000	334,000	811,000
Local [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	30,213,000	31,122,000	32,500,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	25,210,000	24,705,000	25,362,000
Non-escrow retention receivable - 1 to 90 days past due	654,000	1,024,000	1,496,000
Non-escrow retention receivable - over 90 days past due	4,349,000	5,393,000	5,642,000
Private [Member] | Non Escrow [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts, Notes, Loans and Financing Receivable, Gross, Current	7,751,000	8,400,000	5,814,000
Financing Receivable, Recorded Investment, Aging [Abstract]
Non-escrow retention receivable - current	6,591,000	6,817,000	4,571,000
Non-escrow retention receivable - 1 to 90 days past due	107,000	287,000	634,000
Non-escrow retention receivable - over 90 days past due	$ 1,053,000	$ 1,296,000	$ 609,000