Intangible Assets - Indefinite Lived Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Indefinite-lived Intangible Assets by Major Class [Line Items]
Goodwill	$ 55,419	$ 9,900
Total unamortized intangible assets	55,812	10,293
Use rights and other [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Use rights and other	393	393
Construction [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Goodwill	29,190	6,937
Large Project Construction [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Goodwill	24,115	850
Construction Materials [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Goodwill	$ 2,114	$ 2,113