Intangible Assets - Indefinite Lived Intangible Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Indefinite-lived Intangible Assets by Major Class [Line Items]
Goodwill	$ 53,799,000	$ 53,799,000	$ 53,799,000
Construction [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Goodwill	29,260,000	29,260,000	29,260,000
Large Project Construction [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Goodwill	22,593,000	22,593,000	22,593,000
Construction Materials [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Goodwill	1,946,000	1,946,000	1,946,000
Other Noncurrent Assets [Member] | Use Rights [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Use rights.	$ 400,000	$ 400,000	$ 400,000