Estimate of Fair Value of Secured Debt Obligations (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
TriplePoint - Matures December 2014 | Carrying Value
Accounts Notes And Loans Receivable [Line Items]
Debt instrument fair value	$ 667	$ 917
TriplePoint - Matures December 2014 | Fair Value
Accounts Notes And Loans Receivable [Line Items]
Debt instrument fair value	634	847
TriplePoint - Matures October 2015 | Carrying Value
Accounts Notes And Loans Receivable [Line Items]
Debt instrument fair value	6,657	6,657
TriplePoint - Matures October 2015 | Fair Value
Accounts Notes And Loans Receivable [Line Items]
Debt instrument fair value	6,024	5,942
TriplePoint - Matures January 2016 | Carrying Value
Accounts Notes And Loans Receivable [Line Items]
Debt instrument fair value	3,495	3,495
TriplePoint - Matures January 2016 | Fair Value
Accounts Notes And Loans Receivable [Line Items]
Debt instrument fair value	$ 3,120	$ 3,079