Fair Value Measurements - Trust's Financial Assets for which Fair Value Option was Elected (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments at fair value	$ 226	$ 226
Loan Securities Carried at Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments at fair value	$ 226	$ 226