Summary of Significant Accounting Policies - Useful Lives for Major Categories of Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2014
Land Improvements | Lower end
Property and Equipment [Line Items]
Property and equipment, useful life	50 years
Land Improvements | Upper end
Property and Equipment [Line Items]
Property and equipment, useful life	50 years
Buildings | Lower end
Property and Equipment [Line Items]
Property and equipment, useful life	28 years
Buildings | Upper end
Property and Equipment [Line Items]
Property and equipment, useful life	40 years
Furniture Fixtures Equipment and Purchased Software | Lower end
Property and Equipment [Line Items]
Property and equipment, useful life	3 years
Furniture Fixtures Equipment and Purchased Software | Upper end
Property and Equipment [Line Items]
Property and equipment, useful life	5 years