Summary of Significant Accounting Pronouncements (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Significant Accounting Policies [Line Items]
Revenue Recognition, Percentage of Completion, Recognition Threshold	25.00%
Goodwill	$ 53,799,000		$ 55,419,000
Cash and cash equivalents	229,121,000		321,990,000		256,990,000	252,022,000
Capitalized Computer Software, Additions	2,500,000		10,900,000		14,000,000
Change in Loss Assumptions, Potential Effect on Operating Results and Financial Position	1,000,000
Minimum [Member]
Significant Accounting Policies [Line Items]
Workers' Compensation Liability	500,000
Maximum [Member]
Significant Accounting Policies [Line Items]
Workers' Compensation Liability	1,000,000
Software Development [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Software Development [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Consolidated Construction Joint Venture [Member] | Joint Venture Consolidated [Member]
Significant Accounting Policies [Line Items]
Cash and cash equivalents	38,800,000	[1]	105,865,000	[1]
Consolidated Construction Joint Venture [Member] | Joint Venture Consolidated [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Contract Value of Active Construction Joint Venture Projects	400,000
Consolidated Construction Joint Venture [Member] | Joint Venture Consolidated [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Contract Value of Active Construction Joint Venture Projects	337,000,000
Northwest Construction Materials [Member]
Significant Accounting Policies [Line Items]
Goodwill	1,900,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	48.00%
Kenny
Significant Accounting Policies [Line Items]
Goodwill	$ 22,400,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	42.00%

[1] The volume and stage of completion of contracts from our consolidated construction joint ventures may cause fluctuations in cash and cash equivalents as well as billings in excess of costs and estimated earnings between periods.