Significant Accounting Policies - Estimated Useful Lives of Property (Details)	12 Months Ended
	Dec. 31, 2014
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	10 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	40 years
Water, power and sewer systems | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	5 years
Water, power and sewer systems | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	50 years
Rock crushing and asphalt plants | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	25 years
Rock crushing and asphalt plants | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	35 years
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	2 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	35 years
Other property improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	3 years
Other property improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of property	35 years