Fair Value Measurements - Additional Information (Detail) (USD $)	12 Months Ended						6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Occupancy [Member]	Dec. 31, 2011 Occupancy [Member]	Dec. 31, 2013 Significant Unobservable Inputs (Level 3) [Member]	Jun. 30, 2013 Memphis [Member]	Sep. 30, 2013 Memphis [Member]	Dec. 31, 2012 Atlanta Georgia [Member]	Dec. 31, 2012 Denton Texas [Member]	Dec. 31, 2013 Equity Investments [Member]	Dec. 31, 2012 Equity Investments [Member]	Dec. 31, 2011 Equity Investments [Member]	Dec. 31, 2013 Real Estate Investment [Member]	Dec. 31, 2012 Real Estate Investment [Member]	Dec. 31, 2011 Real Estate Investment [Member]
Financial Instruments And Fair Value Measurements [Line Items]
Transfers between Level 1 and Level 2 fair value assets	$ 0	$ 0
Transfers between Level 1 and Level 2 fair value liabilities	0	0
Loan securities carried at fair value	226,000	11,000				226,000
Loan security face value						20.00%
Trust recognized other-than-temporary impairment losses											7,687,000	0	21,058,000
Impairment charges							154,000	698,000	1,738,000	824,000	0	0	0	2,904,000	3,260,000	7,600,000
Property impairment charges	2,904,000	3,260,000	7,600,000	2,750,000	3,000,000
Net unrealized gains	$ 73,000	$ 7,363,000	$ 5,526,000