Real Estate Investments - Real Estate Projects (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013 sqft
Columbia, South Carolina [Member]
Real Estate Properties [Line Items]
Number of Square Feet	450,000
Initial Lease Term	10 years 6 months	[1]
Percent of Property Owned	100.00%
Property Investment, Amount	$ 14,745,000
Remaining Investment Amount	7,325,000
Estimated Total Investment	22,070,000
Interest Costs Capitalized	37,000
The Woodlands, Texas [Member]
Real Estate Properties [Line Items]
Number of Square Feet	150,000
Percent of Property Owned	90.00%
Property Investment, Amount	7,257,000
Remaining Investment Amount	26,775,000
Estimated Total Investment	34,032,000
Interest Costs Capitalized	$ 45,000

[1] The lease is in force and the 10.5 year lease term will commence upon substantial completion of the building.