Notes Payable - Schedule of Information Related to Lines of Credit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
Maximum amount outstanding	$ 295,588	$ 208,894
Average amount outstanding	$ 236,860	$ 191,248
Weighted average interest rate, during the period	2.35%	2.41%
Prime interest rate, end of period	3.50%	3.25%