Securities and Loan Securities Carried at Fair Value - Securities and Loan Securities Carried at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Option, Quantitative Disclosures [Line Items]
Cost		$ 15,876
Fair Value		19,694
Common Shares of Beneficial Interest [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cost		15,876
Fair Value		19,694
Loan Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cost	161	161
Fair Value	226	11
Securities Carried at Fair Value Total [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cost	161	16,037
Fair Value	$ 226	$ 19,705