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Credit Facilities - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2015
Mar. 22, 2013
Line of Credit Facility [Line Items]    
Line of credit, available borrowings   $ 50,000,000
Current borrowing capacity   $ 10,000,000
Minimum unrestricted cash balance requirement $ 50,000,000  
Interest rate on borrowings at LIBOR plus, minimum 1.75%  
Interest rate on borrowings at LIBOR plus, maximum 1.75%  
Line of credit, amount outstanding $ 0