Borrowings - Information Related to Credit Agreements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Abstract]
Average daily utilization of borrowings	$ 69,964	$ 85,874	$ 102,512
Interest expense including commitment fees, excluding amortization of deferred loan fees	$ 1,307	$ 1,425	$ 1,765
Weighted average interest rate	1.90%	1.70%	1.70%